For some applications, we need to reduce the CPU Frequency, but if you are not familiar with our BSP or our devices probably you need some help to do some configurations.   In this post, I will share the configuration to set up lower frequencies (100MHz, 200MHz, 400Mhz, 600MHz, 800MHz, and 1000MHz) on iMX8MP, iMX8MN, and iMX8MM.   Note: Works on Kernel 6.1.xx (not tested on oldest BSP)   1- We have to modify the PLL driver to set the proper parameters to lower frequencies. The file to modify is "clk-pll14xx.c" adding the following lines:   https://github.com/nxp-imx/linux-imx/blob/770c5fe2c1d1529fae21b7043911cd50c6cf087e/drivers/clk/imx/clk-pll14xx.c#L57   static const struct imx_pll14xx_rate_table imx_pll1416x_tbl[] = { PLL_1416X_RATE(1800000000U, 225, 3, 0), PLL_1416X_RATE(1600000000U, 200, 3, 0), PLL_1416X_RATE(1500000000U, 375, 3, 1), PLL_1416X_RATE(1400000000U, 350, 3, 1), PLL_1416X_RATE(1200000000U, 300, 3, 1), PLL_1416X_RATE(1000000000U, 250, 3, 1), PLL_1416X_RATE(800000000U, 200, 3, 1), PLL_1416X_RATE(750000000U, 250, 2, 2), PLL_1416X_RATE(700000000U, 350, 3, 2), PLL_1416X_RATE(600000000U, 300, 3, 2), + PLL_1416X_RATE(400000000U, 200, 3, 2), + PLL_1416X_RATE(200000000U, 200, 3, 3), + PLL_1416X_RATE(100000000U, 200, 3, 4), };   2- Once the pll driver has been modified, only we have to add the values on the opp-table according to the device that you will use.   2.1- For iMX 8MP:   https://github.com/nxp-imx/linux-imx/blob/lf-6.1.y/arch/arm64/boot/dts/freescale/imx8mp.dtsi         a53_opp_table: opp-table { compatible = "operating-points-v2"; opp-shared; + opp-100000000 { + opp-hz = /bits/ 64 <100000000>; + opp-microvolt = <850000>; + opp-supported-hw = <0x8a0>, <0x7>; + clock-latency-ns = <150000>; + opp-suspend; + }; + opp-200000000 { + opp-hz = /bits/ 64 <200000000>; + opp-microvolt = <850000>; + opp-supported-hw = <0x8a0>, <0x7>; + clock-latency-ns = <150000>; + opp-suspend; + }; + opp-400000000 { + opp-hz = /bits/ 64 <400000000>; + opp-microvolt = <850000>; + opp-supported-hw = <0x8a0>, <0x7>; + clock-latency-ns = <150000>; + opp-suspend; + }; + opp-600000000 { + opp-hz = /bits/ 64 <600000000>; + opp-microvolt = <850000>; + opp-supported-hw = <0x8a0>, <0x7>; + clock-latency-ns = <150000>; + opp-suspend; + }; + opp-800000000 { + opp-hz = /bits/ 64 <800000000>; + opp-microvolt = <850000>; + opp-supported-hw = <0x8a0>, <0x7>; + clock-latency-ns = <150000>; + opp-suspend; + }; + opp-1000000000 { + opp-hz = /bits/ 64 <1000000000>; + opp-microvolt = <850000>; + opp-supported-hw = <0x8a0>, <0x7>; + clock-latency-ns = <150000>; + opp-suspend; + }; opp-1200000000 { opp-hz = /bits/ 64 <1200000000>;   2.2 For iMX8MM:   https://github.com/nxp-imx/linux-imx/blob/lf-6.1.y/arch/arm64/boot/dts/freescale/imx8mm.dtsi     a53_opp_table: opp-table { compatible = "operating-points-v2"; opp-shared; + opp-100000000 { + opp-hz = /bits/ 64 <100000000>; + opp-microvolt = <850000>; + opp-supported-hw = <0xe>, <0x7>; + clock-latency-ns = <150000>; + opp-suspend; + }; + opp-200000000 { + opp-hz = /bits/ 64 <200000000>; + opp-microvolt = <850000>; + opp-supported-hw = <0xe>, <0x7>; + clock-latency-ns = <150000>; + opp-suspend; + }; + opp-400000000 { + opp-hz = /bits/ 64 <400000000>; + opp-microvolt = <850000>; + opp-supported-hw = <0xe>, <0x7>; + clock-latency-ns = <150000>; + opp-suspend; + }; + opp-600000000 { + opp-hz = /bits/ 64 <600000000>; + opp-microvolt = <850000>; + opp-supported-hw = <0xe>, <0x7>; + clock-latency-ns = <150000>; + opp-suspend; + }; + opp-800000000 { + opp-hz = /bits/ 64 <800000000>; + opp-microvolt = <850000>; + opp-supported-hw = <0xe>, <0x7>; + clock-latency-ns = <150000>; + opp-suspend; + }; + opp-1000000000 { + opp-hz = /bits/ 64 <1000000000>; + opp-microvolt = <850000>; + opp-supported-hw = <0xe>, <0x7>; + clock-latency-ns = <150000>; + opp-suspend; + }; opp-1200000000 { opp-hz = /bits/ 64 <1200000000>;   2.3- For iMX8MN:   https://github.com/nxp-imx/linux-imx/blob/lf-6.1.y/arch/arm64/boot/dts/freescale/imx8mn.dtsi   compatible = "operating-points-v2"; opp-shared; + opp-100000000 { + opp-hz = /bits/ 64 <100000000>; + opp-microvolt = <850000>; + opp-supported-hw = <0xb00>, <0x7>; + clock-latency-ns = <150000>; + opp-suspend; + }; + + opp-200000000 { + opp-hz = /bits/ 64 <200000000>; + opp-microvolt = <850000>; + opp-supported-hw = <0xb00>, <0x7>; + clock-latency-ns = <150000>; + opp-suspend; + }; + + opp-400000000 { + opp-hz = /bits/ 64 <400000000>; + opp-microvolt = <850000>; + opp-supported-hw = <0xb00>, <0x7>; + clock-latency-ns = <150000>; + opp-suspend; + }; + + opp-600000000 { + opp-hz = /bits/ 64 <600000000>; + opp-microvolt = <850000>; + opp-supported-hw = <0xb00>, <0x7>; + clock-latency-ns = <150000>; + opp-suspend; + }; + + opp-800000000 { + opp-hz = /bits/ 64 <800000000>; + opp-microvolt = <850000>; + opp-supported-hw = <0xb00>, <0x7>; + clock-latency-ns = <150000>; + opp-suspend; + }; + + opp-1000000000 { + opp-hz = /bits/ 64 <1000000000>; + opp-microvolt = <850000>; + opp-supported-hw = <0xb00>, <0x7>; + clock-latency-ns = <150000>; + opp-suspend; + }; + opp-1200000000 { opp-hz = /bits/ 64 <1200000000>; opp-microvolt = <850000>;   After that, you should note the changes under Linux.   These commands return information about the system and the current settings.   • The kernel is pre-configured to support only certain frequencies. The list of frequencies currently supported can be obtained from: cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_frequencies   • To get the available scaling governors: cat /sys/devices/system/cpu/*/cpufreq/scaling_available_governors   • To check the current CPU frequency: cat /sys/devices/system/cpu/*/cpufreq/cpuinfo_cur_freq   The frequency is displayed depending on the governor set.   • To check the maximum frequency: cat /sys/devices/system/cpu/*/cpufreq/cpuinfo_max_freq   • To check the minimum frequency: cat /sys/devices/system/cpu/*/cpufreq/cpuinfo_min_freq   These commands set a constant CPU frequency:   • Use the maximum frequency: echo performance > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor   • Use the current frequency to be the constant frequency: echo userspace > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor   • The following two commands set the scaling governor to a specified frequency, if that frequency is supported.   If the frequency is not supported, the closest supported frequency is used:   echo userspace > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor echo <frequency> > /sys/devices/system/cpu/cpu0/cpufreq/scaling_setspeed    

Dynamic debug is designed to allow you to dynamically at runtime  enable/disable  kernel code to obtain additional kernel information. Currently, if ``CONFIG_DYNAMIC_DEBUG`` is set, then all ``pr_debug()``/``dev_dbg()`` and ``print_hex_dump_debug()``/``print_hex_dump_bytes()`` calls can be dynamically enabled per-callsite.    

In the IMX8MM SDK unfortunately we cannot find any example about of use a GPIO as an input with interrupt.  To use a GPIO as input with interrupt we need to keep in mind how the GPIO IRQs works in the ARM Cortex M4.   We can find in Table 7-2 (CM4 Interrupt Summary) of IMX8MMRM (IMX8MM Reference Manual) the GPIOs IRQs are divided by two parts:     Combined interrupt indication for GPIOn signal 0 throughout 15  Combined interrupt indication for GPIOn signal 16 throughout 31    This basically means, the pines of GPIOn from 0 to 15 are handled by Combined interrupt indication for GPIOn signal 0 throughout 15 and the pines from 16 to 31 are handled by Combined interrupt indication for GPIOn signal 16 throughout 31.    In SDK we can find these definitions in:  <SDK root>/devices/MIMX8MM6/MIMX8MM6_cm4.h (Remember this is for IM8MM SDK)    In this example I will use GPIO5_IO12 (ECSPI2_MISO) as Input with IRQ and GPIO5_IO11 (ECSPI_MOSI) as Output of IMX8MM-EVK. I will connect the Output to the Input and will see the behavior of the IRQ in Rising and Falling edge.    For this example I will connect ECSPI2_MOSI (GPIO5_IO11) to ECSPI_MISO (GPIO5_IO12):   See the below definitions:   #define IN_GPIO   GPIO5  This define the GPIO base of the IN pin  #define IN_GPIO_PIN  12u  This define the pin number (for in)  #define IN_IRQ  GPIO5_Combined_0_15_IRQn  This define the IRQ number (72 in this case)  #define GPIO_IRQ_HANDLER  GPIO5_Combined_0_15_IRQHandler  This is a "pointer" to function that will handle the interrupt  #define IN_NAME  "IN GPIO5_IO12"  This is only a name or description for the pin    See below definitions:    #define OUT_GPIO  GPIO5  This is the GPIO base of OUT pin  #define OUT_GPIO_PIN  11u  This define the pin number (for out)  #define OUT_NAME  "OUT GPIO5_IO11"  This is only a name or description for the pin      Now the below section is the IRQ handler (which was defined before)😞   The GPIO_ClearPinsInterruptFlags(IN_GPIO, 1u << IN_GPIO_PIN); refers to GPIOx_ISR register:      For this example, the IRQ Handler will print "IRQ detected ............" in each interrupt.    We will create two different GPIOs config, one for Output and other one for Input with IRQ Falling edge:    Then configure the GPIOs and IRQ:     EnableIRQ refers to enable the 72 IRQ.   GPIO_PortEnableInterrupts refers to GPIOx_IMR: Finally, the example put the out GPIO5_IO11 in High state and then in low state many. First the IRQ is configured as Falling edge, then as Rising edge.     I will attach the complete source file.    To compile it you can use ARMGCC toolchain directly, but I like to use VSCode with MCUXpresso integration.  Once, when you have your .bin file (in my case igpio_led_output.bin) you can load to board with UUU tool: In your Linux machine: sudo uuu -b fat_write igpio_led_output.bin mmc 2:1 gpio.bin In U-boot board: u-boot=> fastboot 0   Then, when the .bin file was loaded, you can load to the CORTEX M4 in U-boot whit: u-boot=> fatload mmc 2:1 ${loadaddr} gpio.bin 7076 bytes read in 14 ms (493.2 KiB/s) u-boot=> cp.b 0x80000000 0x7e0000 0x10000 u-boot=> bootaux 0x7e0000 ## No elf image ar address 0x007e0000 ## Starting auxiliary core stack = 0x20020000, pc = 0x1FFE02CD... u-boot=>   NOTE: You can load the binary to cortex m4 with Custom bootscripts for practicity.   Once the binary loaded in M4 core you should see in seria terminal this logs (Remember GPIO5_IO11 and GPIO5_IO12 must be connected to get the same logs):    And the logs when you disconnect the GPIO5_IO11 and GPIO5_IO12 in execution time:  🔴Disconnection (Red color) 🔵Reconnection (Blue color)   I hope this can helps.     Best regards!    Salas. 

Hello there. Here is a good way to use U-boot in an efficient way with custom scripts. The bootscript is an script that is automatically executed when the boot loader starts, and before the OS auto boot process. The bootscript allows the user to execute a set of predefined U-Boot commands automatically before proceeding with normal OS boot. This is especially useful for production environments and targets which don’t have an available serial port for showing the U-Boot monitor. This information can be find in U-Boot Reference Manual.   I will take the example load a binary file in CORTEX M4 of IMX8MM-EVK. In my case, I have the binary file in MMC 2:1 called gpio.bin and I will skip those steps because that is not the goal.   First, you need the u-boot-tools installed in your Linux machine: sudo apt install u-boot-tools   That package provide to us the tool mkimage to convert a text file (.src, .txt) file to a bootscript file for U-Boot.   Now, create your custom script, in this case a simple script for load binary file in Cortex M4: nano mycustomscript.scr  and write your U-Boot commands: fatload mmc 2:1 0x80000000 gpio.bin cp.b 0x80000000 0x7e0000 0x10000 bootaux 0x7e0000   Now we can convert the text file to bootscript with mkimage. Syntax: mkimage -T script -n "Bootscript" -C none -d <input_file> <output_file> mkimage -T script -n "Bootscript" -C none -d mycustomscript.scr LCM4-bootscript   This will create a file called LCM4-bootscript (Or as your called it).   A way to load this bootscript file to U-Boot is using the UUU tool, in U-Boot set the device in fastboot with command: u-boot=> fastboot 0 Then in linux with the board connected through USB to PC run the command: sudo uuu -b fat_write LCM4-bootscript mmc 2:1 LCM4-bootscript   Now we have our bootscript in U-Boot in MMC 2:1.   Finally, we can run the bootscript in U-Boot: u-boot=> load mmc 2:1 ${loadaddr} LCM4-bootscript 158 bytes read in 2 ms (77.1 KiB/s) u-boot=> source ${loadaddr} ## Executing script at 40400000 6656 bytes read in 5 ms (1.3 MiB/s) ## No elf image at address 0x007e0000 ## Starting auxiliary core stack = 0x20020000, pc = 0x1FFE02CD...   And the Cortex M4 booted successfully:    I hope this can helps to you.   Best regards.   Salas.  

Board : i.MX93 EVK BSP: imx L6.1.1-1.0.0 Gui guider: 1.6.1   We have a GUI software tool called GUI Guider. It is a user-friendly graphical user interface development tool from NXP that enables the rapid development of high quality displays with the open-source LVGL graphics library. The GUI demo can run on the i.MX93EVK board. (https://www.nxp.com/design/software/development-software/gui-guider:GUI-GUIDER)   This document will show you an example how the buttons(gpio) on the EVK to interacting with the GUI. Basically, customer could use the same method to use the gpio pins to control everything.   On the i.MX93 EVK board, there are two buttons BTN1 and BTN2. They are connected to GPIO IO23 and GPIO IO24. Below is the schematic.    Buttons on the board.      SW1005 on the board   In the EVK's device tree file, need to change the pinmux for the two buttons like this: pinctrl_spdif: spdifgrp { fsl,pins = < // MX93_PAD_GPIO_IO22__SPDIF_IN 0x31e // MX93_PAD_GPIO_IO23__SPDIF_OUT 0x31e MX93_PAD_GPIO_IO23__GPIO2_IO23 0x31e MX93_PAD_GPIO_IO24__GPIO2_IO24 0x31e >; note: all the pins are defined in imx93-pinfunc.h.   For getting the input value of the buttons in user's space, I use the sysfs gpio. Build the imx-image-multimedia image first and then select the GPIO_SYSFS in kernel's menuconfig.   $ DISTRO=fsl-imx-xwayland MACHINE=imx93evk source imx-setup-release.sh -b build-xwayland $ bitbake imx-image-multimedia   After the build completed, go to the kernel's menuconfig to select the GPIO sysfs. $ bitbake linux-imx -c menuconfig [*] General setup-> Configure standard kernel features (expert users) [*] Device Drivers->GPIO Support-> /sys/class/gpio/... (sysfs interface)   Build the whole image again by "$ bitbake imx-image-multimedia".   Using the UUU to program the image to the EMMC on the EVK board. uuu -b emmc_all imx-image-multimedia-imx93evk.rootfs.wic.zst   Connect the LVDS to the board. Use the corresponding dtb to boot the board. In u-boot, set the dtb file. => setenv fdtfile imx93-11x11-evk-boe-wxga-lvds-panel.dtb => saveenv   Then restart the board. After the board boot up, it will look like below.     You need to calibrate the LVDS touch screen before it can normally use. Please use this command: $ weston-touch-calibrator LVDS-1     Now, build the GUI guider example. I use the Air Conditioner example. Download the GUI guider from the gui-guider web page: https://www.nxp.com/design/software/development-software/gui-guider:GUI-GUIDER   Follow the steps from the below web page to build the i.MX BSP and the gui example code. https://docs.nxp.com/bundle/GUIGUIDERUG-1.6.1/page/topics/yocto.html   After the gui-guider build completed, use the 'scp' command to transfer the gui_guider executable file to the board. Execute the command on your host PC like this: $ scp bld-imx93evk/tmp/work/armv8a-poky-linux/gui-guider/1.6.0-r0/image/usr/bin/gui_guider root@<Your Board IP address>:/ Note: You could use a router to connect your board and your host PC. They are on the same network so could use the 'scp' command to transfer the file to your board.   On your board, type the following commands to execute the gui. $ chmod 755 gui_guider $ ./gui_guider &   Then the GUI is running like this:   Now, let me explain how to find out the gpio number. Type the following command to show the mapping addresses of gpio. root@imx93evk:/# cat /sys/kernel/debug/gpio gpiochip3: GPIOs 0-31, parent: platform/47400080.gpio, 47400080.gpio: gpiochip0: GPIOs 32-63, parent: platform/43810080.gpio, 43810080.gpio: gpiochip1: GPIOs 64-95, parent: platform/43820080.gpio, 43820080.gpio: gpio-64 ( |cd ) in hi IRQ ACTIVE LOW gpio-71 ( |regulator-usdhc2 ) out lo gpiochip2: GPIOs 96-127, parent: platform/43830080.gpio, 43830080.gpio: gpiochip6: GPIOs 472-477, parent: i2c/0-001a, wm8962, can sleep: gpiochip5: GPIOs 478-487, parent: platform/adp5585-gpio.1.auto, adp5585-gpio, can sleep: gpio-479 ( |regulator-audio-pwr ) out hi gpio-483 ( |regulator-can2-stby ) out hi ACTIVE LOW gpio-486 ( |enable ) out hi gpiochip4: GPIOs 488-511, parent: i2c/1-0022, 1-0022, can sleep: gpio-492 ( |Headphone detection ) in lo IRQ gpio-501 ( |? ) out hi gpio-502 ( |regulator-vdd-12v ) out hi gpio-505 ( |reset ) out lo gpio-507 ( |? ) out hi gpio-508 ( |reset ) out lo ACTIVE LOW   The gpio pins of two buttons are GPIO2_IO23 and GPIO2_IO24. They are belongs to gpio2. In the imx93.dtsi, the gpio2's address is "gpio2: gpio@43810080". So, base on the information output from "/sys/kernel/debug/gpio", the gpio2 is mapping to "gpiochip0: GPIOs 32-63". So, the GPIO2_IO23 is 32+23=55, and the GPIO2_IO24 is 32+24=56.   To verify the gpio number is correct or not. We could do the following test. root@imx93evk:/# echo 55 > /sys/class/gpio/export root@imx93evk:/# echo in > /sys/class/gpio/gpio55/direction root@imx93evk:/# echo 56 > /sys/class/gpio/export root@imx93evk:/# echo in > /sys/class/gpio/gpio56/direction   Then, run these two commands to check the values. root@imx93evk:/# cat /sys/class/gpio/gpio55/value root@imx93evk:/# cat /sys/class/gpio/gpio55/value   When the button is not pressed, the value is 1. When press the button, the value is 0.  We could add the same in the GUI's custom.c. Open the GUI Guider software and add the code in the custom.c. /********************* * INCLUDES *********************/ #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <errno.h> #include <fcntl.h> #include "lvgl.h" #include "custom.h" #include "ui_Aircon.h" #include "guider_customer_fonts.h" /********************** * STATIC VARIABLES **********************/ int fdbtn1,fdbtn2,fdgpio; int btn1_pressed; int btn2_pressed; char btn1_value, btn2_value; void custom_func(void) { fdbtn1 = open("/sys/class/gpio/gpio55/value", O_RDWR); fdbtn2 = open("/sys/class/gpio/gpio56/value", O_RDWR); read(fdbtn1, &btn1_value, 1); read(fdbtn2, &btn2_value, 1); if(btn1_value=='0' && btn1_pressed) { btn1_pressed=0; ui_aircon_update_temp(0, kAIRCON_TempUp); } if(btn1_value=='1') btn1_pressed=1; if(btn2_value=='0' && btn2_pressed) { btn2_pressed=0; ui_aircon_update_temp(0, kAIRCON_TempDown); } if(btn2_value=='1') btn2_pressed=1; close(fdbtn1); close(fdbtn2); } void custom_init(lv_ui *ui) { fdbtn1 = open("/sys/class/gpio/gpio55/value", O_WRONLY); if (fdbtn1 == -1) { fdgpio = open("/sys/class/gpio/export", O_WRONLY); write(fdgpio,"55",3); write(fdgpio,"56",3); close(fdgpio); fdgpio = open("/sys/class/gpio/gpio55/direction", O_WRONLY); write(fdgpio,"in",3); close(fdgpio); fdgpio = open("/sys/class/gpio/gpio56/direction", O_WRONLY); write(fdgpio,"in",3); close(fdgpio); } else close(fdbtn1); ... ... ... ...   Add the custom_func() in the custom.h. #ifndef __CUSTOM_H_ #define __CUSTOM_H_ #ifdef __cplusplus extern "C" { #endif #include "gui_guider.h" void custom_init(lv_ui *ui); + void custom_func(void);   Also, need to add the custom function() into the dead loop in main.c.   To modify the code, bld-imx93evk$ vim tmp/work/armv8a-poky-linux/gui-guider/1.6.0-r0/gui-guider-1.6.0/ports/linux/main.c   while(1) { + custom_func(); // <--- Add the custom function here. /* Periodically call the lv_task handler. * It could be done in a timer interrupt or an OS task too.*/ time_till_next = lv_wayland_timer_handler(); #if LV_USE_VIDEO video_play(&guider_ui); #endif /* Run until the last window closes */ if (!lv_wayland_window_is_open(NULL)) { break; }   Re-build the code after modified. bld-imx93evk$ bitbake gui-guider -c compile -f   Build the whole image again. bld-imx93evk$ bitbake gui-guider Then use the 'scp' command to transfer the new gui-guider file to the board.   Finally, you can use the buttons on the EVK board to set the temperature up and down.                          

How to use UART4 on iMX8M from Linux User Space   The UART4 on iMX8MM-EVK and iMX8MN-EVK are thinking of debugging the M core which is not usable on Linux user space by default on pre-compiled images.   To use the UART4 on Linux user space you have to do the next modifications on the device tree and atf to assign that peripheral to Linux User Space     https://github.com/nxp-imx/imx-atf/blob/lf_v2.6/plat/imx/imx8m/imx8mm/imx8mm_bl31_setup.c     iMX8MN-EVK   imx8mn_bl31_setup.c   https://github.com/nxp-imx/imx-atf/blob/lf_v2.6/plat/imx/imx8m/imx8mn/imx8mn_bl31_setup.c   /* Master domain assignment */ RDC_MDAn(RDC_MDA_M7, DID1), /* peripherals domain permission */ - RDC_PDAPn(RDC_PDAP_UART4, D1R | D1W), + RDC_PDAPn(RDC_PDAP_UART4, D0R | D0W), RDC_PDAPn(RDC_PDAP_UART2, D0R | D0W), RDC_PDAPn(RDC_PDAP_RDC, D0R | D0W | D1R),       Device tree configurations for iMX8MN-EVK   iMX8MN-EVK.dtsi   https://github.com/nxp-imx/linux-imx/blob/lf-6.1.y/arch/arm64/boot/dts/freescale/imx8mn-evk.dtsi   &uart3 { pinctrl-names = "default"; pinctrl-0 = <&pinctrl_uart3>; assigned-clocks = <&clk IMX8MN_CLK_UART3>; assigned-clock-parents = <&clk IMX8MN_SYS_PLL1_80M>; uart-has-rtscts; status = "okay"; }; + &uart4 { + pinctrl-names = "default"; + pinctrl-0 = <&pinctrl_uart4>; + assigned-clocks = <&clk IMX8MN_CLK_UART4>; + assigned-clock-parents = <&clk IMX8MN_SYS_PLL1_80M>; + status = "okay"; + }; ********************** pinctrl_uart3: uart3grp { fsl,pins = < MX8MN_IOMUXC_ECSPI1_SCLK_UART3_DCE_RX 0x140 MX8MN_IOMUXC_ECSPI1_MOSI_UART3_DCE_TX 0x140 MX8MN_IOMUXC_ECSPI1_SS0_UART3_DCE_RTS_B 0x140 MX8MN_IOMUXC_ECSPI1_MISO_UART3_DCE_CTS_B 0x140 >; }; + pinctrl_uart4: uart4grp { + fsl,pins = < + MX8MN_IOMUXC_UART4_RXD_UART4_DCE_RX 0x140 + MX8MN_IOMUXC_UART4_TXD_UART4_DCE_TX 0x140 + >; + };   iMX8MM-EVK   https://github.com/nxp-imx/imx-atf/blob/lf_v2.6/plat/imx/imx8m/imx8mm/imx8mm_bl31_setup.c   imx8mm_bl31_setup.c   /* Master domain assignment */ RDC_MDAn(RDC_MDA_M7, DID1), /* peripherals domain permission */ - RDC_PDAPn(RDC_PDAP_UART4, D1R | D1W), + RDC_PDAPn(RDC_PDAP_UART4, D0R | D0W), RDC_PDAPn(RDC_PDAP_UART2, D0R | D0W), RDC_PDAPn(RDC_PDAP_RDC, D0R | D0W | D1R),   Device tree configurations for iMX8MM-EVK   iMX8MM-EVK.dtsi   https://github.com/nxp-imx/linux-imx/blob/lf-6.1.y/arch/arm64/boot/dts/freescale/imx8mm-evk.dtsi   &uart3 { pinctrl-names = "default"; pinctrl-0 = <&pinctrl_uart3>; assigned-clocks = <&clk IMX8MM_CLK_UART3>; assigned-clock-parents = <&clk IMX8MM_SYS_PLL1_80M>; uart-has-rtscts; status = "okay"; }; + &uart4 { + pinctrl-names = "default"; + pinctrl-0 = <&pinctrl_uart4>; + assigned-clocks = <&clk IMX8MM_CLK_UART4>; + assigned-clock-parents = <&clk IMX8MM_SYS_PLL1_80M>; + status = "okay"; + }; ********************** pinctrl_uart3: uart3grp { fsl,pins = < MX8MM_IOMUXC_ECSPI1_SCLK_UART3_DCE_RX 0x140 MX8MM_IOMUXC_ECSPI1_MOSI_UART3_DCE_TX 0x140 MX8MM_IOMUXC_ECSPI1_SS0_UART3_DCE_RTS_B 0x140 MX8MM_IOMUXC_ECSPI1_MISO_UART3_DCE_CTS_B 0x140 >; }; + pinctrl_uart4: uart4grp { + fsl,pins = < + MX8MM_IOMUXC_UART4_RXD_UART4_DCE_RX 0x140 + MX8MM_IOMUXC_UART4_TXD_UART4_DCE_TX 0x140 + >; + };   iMX8MP-EVK   https://github.com/nxp-imx/imx-atf/blob/lf_v2.6/plat/imx/imx8m/imx8mp/imx8mp_bl31_setup.c   imx8mp_bl31_setup.c   RDC_MDAn(RDC_MDA_M7, DID1), RDC_MDAn(RDC_MDA_LCDIF, DID2), RDC_MDAn(RDC_MDA_LCDIF2, DID2), RDC_MDAn(RDC_MDA_HDMI_TX, DID2), /* peripherals domain permission */ + RDC_PDAPn(RDC_PDAP_UART4, D0R | D0W), RDC_PDAPn(RDC_PDAP_UART2, D0R | D0W), RDC_PDAPn(RDC_PDAP_WDOG1, D0R | D0W), RDC_PDAPn(RDC_PDAP_RDC, D0R | D0W | D1R),   Device tree configurations for iMX8MP-EVK   iMX8MP-EVK.dts   https://github.com/nxp-imx/linux-imx/blob/lf-6.1.y/arch/arm64/boot/dts/freescale/imx8mp-evk.dts   &uart3 { pinctrl-names = "default"; pinctrl-0 = <&pinctrl_uart3>; assigned-clocks = <&clk IMX8MP_CLK_UART3>; assigned-clock-parents = <&clk IMX8MP_SYS_PLL1_80M>; fsl,uart-has-rtscts; status = "okay"; }; + &uart4 { + pinctrl-names = "default"; + pinctrl-0 = <&pinctrl_uart4>; + assigned-clocks = <&clk IMX8MP_CLK_UART4>; + assigned-clock-parents = <&clk IMX8MP_SYS_PLL1_80M>; + status = "okay"; + }; ************************************ pinctrl_uart3: uart3grp { fsl,pins = < MX8MP_IOMUXC_ECSPI1_SCLK__UART3_DCE_RX 0x140 MX8MP_IOMUXC_ECSPI1_MOSI__UART3_DCE_TX 0x140 MX8MP_IOMUXC_ECSPI1_SS0__UART3_DCE_RTS 0x140 MX8MP_IOMUXC_ECSPI1_MISO__UART3_DCE_CTS 0x140 >; }; + pinctrl_uart4: uart4grp { + fsl,pins = < + MX8MP_IOMUXC_UART4_RXD__UART4_DCE_RX 0x140 + MX8MP_IOMUXC_UART4_TXD__UART4_DCE_TX 0x140 + >; + };     After compiling the image with the changes previously shown, we obtained this result:      

BSP: L6.1.36 Some customer need use adb under usb ffs. The adb in Yocto can greatly improves development efficiency. This is a demo for enabling adb on Yocto.   Yocto local.conf IMAGE_INSTALL:append = "android-tools android-tools-adbd" PREFERRED_PROVIDER_android-tools-conf = "android-tools-conf-configfs"   Test script for launching adbd modprobe g_ffs idVendor=0x1fc9 idProduct=0x0146 iSerialNumber="ZhimingLiu" mkdir -p /dev/usb-ffs/adb mount -t functionfs adb /dev/usb-ffs/adb -o uid=2000,gid=2000 adbd &   Test on Windows: PS C:\Users\Administrator\Desktop\platform-tools> .\adb.exe devices List of devices attached ZhimingLiu device PS C:\Users\Administrator\Desktop\platform-tools> .\adb.exe shell sh-5.2# uname -a Linux imx8mp-lpddr4-evk 6.1.36+g04b05c5527e9 #1 SMP PREEMPT Fri Nov 24 04:46:22 UTC 2023 aarch64 GNU/Linux sh-5.2# ls config ffs t.sh test2.sh sh-5.2# cd / sh-5.2# ls bin dev home lost+found mnt proc run srv tmp usr boot etc lib media opt root sbin sys unit_tests var sh-5.2#

Platform: Demo images, i.MX8MPlus EVK   Some customer need test ffs gadget function on i.MX8MPlus EVK. Here is demo for ffs test, please connect EVK and Ubuntu PC before test.   Test script: #!/bin/sh # Setup the device (configfs) modprobe libcomposite mkdir -p config mount none config -t configfs cd config/usb_gadget/ mkdir g1 cd g1 echo 0x1fc9 >idVendor echo 0x0146 >idProduct mkdir strings/0x409 echo 12345 >strings/0x409/serialnumber echo "Signal 11" >strings/0x409/manufacturer echo "Test" >strings/0x409/product mkdir configs/c.1 mkdir configs/c.1/strings/0x409 echo "Config1" >configs/c.1/strings/0x409/configuration # Setup functionfs mkdir functions/ffs.usb0 ln -s functions/ffs.usb0 configs/c.1 cd ../../../ mkdir -p ffs mount usb0 ffs -t functionfs cd ffs ffs-test 64 & # from the Linux kernel, with mods! sleep 3 cd .. # Enable the USB device echo 38100000.usb > config/usb_gadget/g1/UDC   EVK log root@imx8mpevk:~# ./test2.sh [ 17.859597] file system registered ffs-test: dbg: ep0: writing descriptors (in v2 format) ffs-test: dbg: ep0: writing strings ffs-test: dbg: ep1: starting ffs-test: dbg: ep2: starting ffs-test: dbg: ep1: starts ffs-test: dbg: ep0: starts ffs-test: dbg: ep2: starts Event BIND Event ENABLE Ubuntu PC log: lzm@lzm-GL552VW:~$ lsusb -D /dev/bus/usb/001/008 Device: ID 1fc9:0146 NXP Semiconductors Test Device Descriptor: bLength 18 bDescriptorType 1 bcdUSB 2.10 bDeviceClass 0 bDeviceSubClass 0 bDeviceProtocol 0 bMaxPacketSize0 64 idVendor 0x1fc9 NXP Semiconductors idProduct 0x0146 bcdDevice 6.01 iManufacturer 1 Signal 11 iProduct 2 Test iSerial 3 12345 bNumConfigurations 1 Configuration Descriptor: bLength 9 bDescriptorType 2 wTotalLength 0x0020 bNumInterfaces 1 bConfigurationValue 1 iConfiguration 4 Config1 bmAttributes 0x80 (Bus Powered) MaxPower 2mA Interface Descriptor: bLength 9 bDescriptorType 4 bInterfaceNumber 0 bAlternateSetting 0 bNumEndpoints 2 bInterfaceClass 255 Vendor Specific Class bInterfaceSubClass 0 bInterfaceProtocol 0 iInterface 5 Source/Sink Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x81 EP 1 IN bmAttributes 2 Transfer Type Bulk Synch Type None Usage Type Data wMaxPacketSize 0x0200 1x 512 bytes bInterval 0 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x01 EP 1 OUT bmAttributes 2 Transfer Type Bulk Synch Type None Usage Type Data wMaxPacketSize 0x0200 1x 512 bytes bInterval 1 Binary Object Store Descriptor: bLength 5 bDescriptorType 15 wTotalLength 0x0016 bNumDeviceCaps 2 USB 2.0 Extension Device Capability: bLength 7 bDescriptorType 16 bDevCapabilityType 2 bmAttributes 0x0000010e BESL Link Power Management (LPM) Supported BESL value 256 us SuperSpeed USB Device Capability: bLength 10 bDescriptorType 16 bDevCapabilityType 3 bmAttributes 0x00 wSpeedsSupported 0x000f Device can operate at Low Speed (1Mbps) Device can operate at Full Speed (12Mbps) Device can operate at High Speed (480Mbps) Device can operate at SuperSpeed (5Gbps) bFunctionalitySupport 1 Lowest fully-functional device speed is Full Speed (12Mbps) bU1DevExitLat 0 micro seconds bU2DevExitLat 0 micro seconds Device Status: 0x0001 Self Powered  

Traditional non-matter devices cannot directly join the matter network. But Matter Bridge solves the problem. Matter bridge can join a Matter network as a Matter device and nonmatter devices need to be mapped to Matter network as a dynamic endpoint. In this way, other Matter devices can communicate with non-matter devices through dynamic endpoints. The Guide is a Matter Zigbee Bridge implement based on i.MX93 + K32W0.     Feature List • Matter over Ethernet • Matter over Wi-Fi • Register and Remove Zigbee Deivces • Connect Zigbee devices into Matter ecosystem seamlessly • Zigbee Devices o OnOff cluster o Temperature Sensor Cluster • Matter Actions o Start Zigbee Network o Zigbee Network Permit Join o Factory Reset • No limitation if migrating to other i.MX MPU like i.MX6ULL, i.MX8MP • OTBR and Zigbee bridge can be integrated into one single device

Usually, device tree source files are not a signal pure dts file. It could include dtsi, dts or C code heads .h files. Need C compiler finish the pre-compile to a pure dts file first. It is integrated inside the like Linux build system(Makefile, etc.). This document shows the original way to compile device tree. This document will show compile device tree under windows.    

i.MX93 DDR stress test tool is different with previous i.MX tool. This Chinese article describe how to debug i.MX93 DDR and introduce DDR config tool usage.

  Platform & BSP :i.MX8MPlus, L6.1.36   The attachments enable the i.MX8MPlus pci function in uboot. lspci in Linux root@imx8mpevk:~# lspci -nn 00:00.0 PCI bridge [0604]: Synopsys, Inc. DWC_usb3 / PCIe bridge [16c3:abcd] (rev 01) 01:00.0 Ethernet controller [0200]: Marvell Technology Group Ltd. Device [1b4b:2b42] (rev 11) pci test results in uboot:  u-boot=> pci BusDevFun VendorId DeviceId Device Class Sub-Class _____________________________________________________________ 00.00.00 0x16c3 0xabcd Bridge device 0x04 u-boot=> pci bar 00.00.00 ID Base Size Width Type ---------------------------------------------------------- 0 0x0000000018000000 0x0000000000100000 32 MEM u-boot=> pci regions 00 Buses 00-01 # Bus start Phys start Size Flags 0 0x0000000000000000 0x000000001ff80000 0x0000000000010000 io 1 0x0000000018000000 0x0000000018000000 0x0000000007f00000 mem 2 0x0000000040000000 0x0000000040000000 0x0000000016000000 mem sysmem 3 0x0000000058000000 0x0000000058000000 0x00000000a8000000 mem sysmem 4 0x0000000100000000 0x0000000100000000 0x00000000c0000000 mem sysmem u-boot=> pci header 00.00.00 vendor ID = 0x16c3 device ID = 0xabcd command register ID = 0x0007 status register = 0x0010 revision ID = 0x01 class code = 0x06 (Bridge device) sub class code = 0x04 programming interface = 0x00 cache line = 0x08 latency time = 0x00 header type = 0x01 BIST = 0x00 base address 0 = 0x18000000 base address 1 = 0x00000000 primary bus number = 0x00 secondary bus number = 0x01 subordinate bus number = 0x01 secondary latency timer = 0x00 IO base = 0x10 IO limit = 0x00 secondary status = 0x0000 memory base = 0x1820 memory limit = 0x1810 prefetch memory base = 0xfff0 prefetch memory limit = 0x0000 prefetch memory base upper = 0x00000000 prefetch memory limit upper = 0x00000000 IO base upper 16 bits = 0x0000 IO limit upper 16 bits = 0x0000 expansion ROM base address = 0x18100000 interrupt line = 0xff interrupt pin = 0x01 bridge control = 0x0000

One of the most popular use cases for embedded systems are projects destinated to show information and interact with users. These views are called GUI or Graphic User Interface which are designed to be intuitive, attractive, consistent, and clear. There are many tools that we can use to achieve great GUIs, mostly implemented for platforms such as Web, Android, and iOS. Here, we will need to introduce the concept of framework, basically, it is a set of tools and rules that provides a minimal structure to start with your development. Frameworks usually comes with configuration files, code snippets, files and folders organization helping us to save time and effort. Also, it is important to review the concept of SDK or Software Development Kit which is a set of tools that allows to build software for specific platforms. Usually supplies debugging tools, documentation, libraries, API’s, emulators, and sample code. Flutter is an open-source UI software development kit by Google that help us to create applications with great GUIs on different platforms from a single codebase. Depends on the reference, you can find Flutter defined as a framework or SDK and both are correct, however, an SDK could be a best definition thanks to Flutter supplies a wide and complete package to create an application in which framework is also included. This article is aimed at those that are in a prototyping stage looking for a different tool to develop projects. Also, this article pretends to be a theoretical introduction explaining the most important concepts. However, is a good practice to learn more about reviewing the official documentation from Flutter. (Flutter documentation | Flutter) Here is the structure used throughout this article: What is Flutter? Flutter details Platforms Programming language Official documentation Flutter for embedded systems What is Flutter? Flutter was officially released by Google in December 2018 with a main aim, to give developers a tool to create applications natively compiled for mobile (Android, iOS), web and desktop (Windows, Linux) from a single codebase. It means that as a developer, Flutter will create a structure with minimal code, configuration files, build files for each operating system, manifests, etc. in which we will add our custom code and finally build this code for our preferred OS. For example, we can create an application to review fruit and vegetable information and compile for Android and iOS with the same code. A basic Flutter development process based on my experience looks like the following diagram: Flutter has the following key features: Cross-platform development. Flutter allows the developer to create applications for different platforms using a single codebase. It means that you will not need to recreate the application for each platform you want to support.   Hot-reload. This feature allows the developer to see changes in real time without restarting the whole application, this results in time savings for your project.   High Performance Flutter apps achieve high performance due to the app code is compiled to native ARM code. With this tool no interpreters are involved.   UI Widgets Flutter supplies a set of widgets (UI components such as boxes, inputs text, buttons, etc.) predefined by UI systems guidelines Material on Android and Cupertino for iOS. Source: Material 3 Design Kit | Figma Community Source: Design - Apple Developer   Great community support. This feature could be subjective but, it is useful when we are developing our project find solutions to known issues or report new ones. Because of Flutter is an open source and is widely implemented in the industry this tool owns a big community, with events, forums, and documentation. Flutter Details Supported Platforms With Flutter you can create applications for: Android iOS Linux Debian Linux Ubuntu macOS web Chrome, Firefox, Safari, Edge Windows Supported deployment platforms | Flutter Programming Language Flutter use Dart, a programming language is an open-source language supported by Google optimized to use on the creation of user interfaces. Dart key features: Statically typed. This feature helps catching errors making the code robust ensuring that the variable’s value always match with the declared variable’s type. Null safety. All variables on Dart are non-nullable which means that every variable must have a non-null value avoiding errors at execution time. This feature also, make the code robust and secure. Async/Await. Dart is client-optimized which means that this language was specially created to ensure the best performance as a client application. Async/Await is a feature part of this optimization making easier to manage network requests and other asynchronous operations. Object oriented. Dart is an object-oriented language with classes and mixin. This is especially useful to use on Flutter with the usage of widgets. Compiler support of Just-In-Time (JIT) and Ahead-of-Time (AOT) JIT provides the support that enables the Hot Reload Flutter feature that I mentioned before. It is a complex mechanism, but Dart “detects” changes in your code and execute only these changes avoiding recompiling all the code. AOT compiler produces efficient ARM code improving start up time and performance. Official documentation Flutter has a rich community and documentation that goes from UI guidelines to an Architectural Overview. You can find the official documentation at the following links: Flutter Official Documentation: Flutter documentation | Flutter Flutter Community: Community (flutter.dev) Dart Official Documentation: Dart documentation | Dart Flutter for embedded systems So far, we know all the excellent features and platforms that Flutter can support. But, what about the embedded systems? On the official documentation we can find that Flutter may be used for embedded systems but in fact there is no an official supported platform. This SDK has been supported by their community, specially there is one repository on GitHub supported by Sony that provides documentation and Yocto recipes to support Flutter on embedded Linux. To understand the reason to differentiate between Flutter for Linux Desktop with official support and to create a specific Flutter support for embedded Linux is important to describe the basics of Flutter architecture. Based on the Flutter documentation the system is designed using layers that can be illustrated as follows:   Source: Flutter architectural overview | Flutter We can see as a top level “Framework” which is a high-level layer that includes widgets, tools and libraries that are in contact with developers. Below “Framework,” the layer “Engine” is responsible of drawing the widgets specified in the previous layer and provides the connection between high-level and low-level code. This layer is mostly written in C++ for this reason Flutter can achieve high performance running applications. Specifically for graphics rendering Flutter implements Impeller for iOS and Skia for the rest of platforms. The bottom layer is “Embedder” which is specific for each target and operating system this layer allows Flutter application to run as a native app providing the access to interact with different services managed by the operating systems such as input, rendering surfaces and accessibility. This layer for Linux Desktop uses GTK/GDK and X11 as backend that is highly dependent of unnecessary libraries and expensive for embedded systems which have constrained resources for computation and memory. The work around founded by Sony’s Flutter for Embedded Linux repository is to change this backend using a widely implemented backend for embedded systems Wayland. The following image illustrates the difference between Flutter for Linux Desktop and Flutter for Embedded Linux.   Source: What's the difference between Linux desktop and Embedded Linux · sony/flutter-embedded-linux Wiki · GitHub   Source: What's the difference between Linux desktop and Embedded Linux · sony/flutter-embedded-linux Wiki · GitHub Here is the link to the mentioned repository: GitHub - sony/flutter-elinux: Flutter tools for embedded Linux (eLinux) Finally, I would like to encourage you to read the official Flutter documentation and consider this tool as a great option compared to widely used tools on embedded devices such as Qt or Chromium. Also, please have a look to a great article written by Payam Zahedi delving into the implementation of Flutter for Embedded Linux measuring performance and giving conclusions about the usage of Flutter in embedded systems. (Flutter on Embedded Devices. Learn how to run Flutter on embedded… | by Payam Zahedi | Snapp Embedded | Medium).    

What is a device tree? The device tree is a data structure that is passed to the Linux kernel to describe the physical devices in a system. Before device trees came into use, the bootloader (for example, U-Boot) had to tell the kernel what machine type it was booting. Moreover, it had to pass other information such as memory size and location, kernel command line, etc. Sometimes, the device tree is confused with the Linux Kernel configuration, but the device tree specifies what devices are available and how they are accessed, not whether the hardware is used. The device tree is a structure composed of nodes and properties: Nodes: The node name is a label used to identify the node. Properties: A node may contain multiple properties arranged with a name and a value. Phandle: Property in one node that contains a pointer to another node. Aliases: The aliases node is an index of other nodes. A device tree is defined in a human-readable device tree syntax text file such as .dts or .dtsi. The machine has one or several .dts files that correspond to different hardware configurations. With these .dts files we can compile them into a device tree binary (.dtb) blobs that can either be attached to the kernel binary (for legacy compatibility) or, as is more commonly done, passed to the kernel by a bootloader like U-Boot. What is Devshell? The Devshell is a terminal shell that runs in the same context as the BitBake task engine. It is possible to run Devshell directly or it may spawn automatically. The advantage of this tool is that is automatically included when you configure and build a platform project so, you can start using it by installing the packages and following the setup of i.MX Yocto Project User's Guide on section 3 “Host Setup”. Steps: Now, let’s see how to compile your device tree files of i.MX devices using Devshell. On host machine. Modify or make your device tree on the next path: - 64 bits. ~/imx-yocto-bsp/<build directory>/tmp/work-shared/<machine>/kernel-source/arch/arm64/boot/dts/freescale - 32 bits. ~/imx-yocto-bsp/<build directory>/tmp/work-shared/<machine>/kernel-source/arch/arm/boot/dts To compile, it is needed to prepare the environment as is mentioned on i.MX Yocto Project User's Guide on section 5.1 “Build Configurations”. $ cd ~/imx-yocto-bsp $ DISTRO=fsl-imx-xwayland MACHINE=<machine> source imx-setup-release.sh -b <build directory> $ bitbake -c devshell virtual/kernel (it will open a new window) On Devshell window. $ make dtbs (after finished, close the Devshell window) On host machine. $ bitbake -c compile -f virtual/kernel $ bitbake -c deploy -f virtual/kernel This process will compile all the device tree files linked to the machine declared on setup environment and your device tree files will be deployed on the next path: ~/imx-yocto-bsp/<build directory>/tmp/deploy/images/<machine> I hope this article will be helpful. Best regards. Jorge.

This is a tool for screen capture under DRM (Direct Render Manager). This also a revised version for previous “drmfbcap” (DRM Framebuffer Capture). Unlike the FB based system under which we can capture the frame buffer easily through reading the device node, the DRM is much more complex and secure-protected. No direct way for reading framebuffer data from user space. Under DRM case, we need to open the DRM device, query the resource, get and map the FB object and then read the buffer eventually. With this tool, we can capture the buffer content from a DRM device and output as raw RGB/YUV data. Features: Capture all planes or specific plane, including hidden/covered planes or planes (overlays) managed by applications directly. Both RGB and YUV supported (auto detect). Tile format (VSI Super-Tile) is also supported. Repeat mode which can capture frames continuously. Tool was built as static linked, in this case, it should be working in both Linux and Android.   Important notes: Behavior of DRM subsystem is different between Linux 4.x and 5.x/6.x. For Linux 4.x, you can capture the RGB buffer without any problem. But, there’s no API for YUV (multi-plane) buffer. To capture YUV, please patch kernel with: “kernel_0001-drm-Add-getfb2-ioctl_L4.14.98.patch”. For Linux 5.x, mapping/capturing the internal buffer is not allowed by default due to security reason. To overcome this temporary (for debug only), patch the kernel with: “0001-drm-enable-mapping-of-internal-object-for-debugging_L5.x.patch”. It contains a minor change to remove this guard. Both patches are included in attachment. To get more details about how to use this tool, try “-h” option to print the usage message. Enjoy!

Customer is asking high-capacity external storage(for example >64GB) support on i.MX BSP, ext4 is ok for HC storage, but it can’t be supported by Windows. Pls find NFTS and exFAT support status on Linux BSP below: Updated test result on L5.4.70.2.3.0 and L6.1.22: L5.4.70.2.3.0 1.You can enable ntfs support in kernel config as below,  ntfs can be mounted normally, but you can only modify existing file content in disk, you can’t create/delete/rename file on disk. > File systems > DOS/FAT/NT Filesystems   Log: root@imx8mpevk:~# mount -t ntfs /dev/sda1 /mnt/fat/ [  662.732869] ntfs: volume version 3.1. root@imx8mpevk:~# cp ntfs-3g /mnt/fat/ cp: cannot create regular file '/mnt/fat/ntfs-3g': Permission denied root@imx8mpevk:~# ls /mnt/fat/ 111.png  Image_org  System Volume Information  gpuinfo.sh root@imx8mpevk:~# vi /mnt/fat/gpuinfo.sh root@imx8mpevk:~# umount /mnt/fat/ root@imx8mpevk:~# ntfs file system can be accessed via ntfs-3g in user space as below //build: wget https://tuxera.com/opensource/ntfs-3g_ntfsprogs-2017.3.23.tgz tar zxvf ntfs-3g_ntfsprogs-2017.3.23.tgz cd ntfs-3g_ntfsprogs-2017.3.23/ source ../../sdk/environment-setup-aarch64-poky-linux   ./configure --host=aarch64-linux --build=aarch64-poky-linux --disable-shared --enable-static   make   ls /src/ntfs-3g   //put it into rootfs cp ntfs-3g /bin   //test log: root@imx8mpevk:/# [ 1058.724471] usb 1-1: USB disconnect, device number 4 [ 1062.058613] usb 1-1: new high-speed USB device number 5 using xhci-hcd [ 1062.214029] usb-storage 1-1:1.0: USB Mass Storage device detected [ 1062.220986] scsi host0: usb-storage 1-1:1.0 [ 1063.235871] scsi 0:0:0:0: Direct-Access     VendorCo ProductCode      2.00 PQ: 0 ANSI: 4 [ 1063.246185] sd 0:0:0:0: [sda] 15728640 512-byte logical blocks: (8.05 GB/7.50 GiB) [ 1063.254023] sd 0:0:0:0: [sda] Write Protect is off [ 1063.259164] sd 0:0:0:0: [sda] No Caching mode page found [ 1063.264540] sd 0:0:0:0: [sda] Assuming drive cache: write through [ 1063.296946]  sda: sda1 [ 1063.300860] sd 0:0:0:0: [sda] Attached SCSI removable disk   root@imx8mpevk:/# ntfs-3g /dev/sda1 /mnt/fat/ root@imx8mpevk:/# ls /mnt/fat/ README  System Volume Information  gpu.sh  gpuinfo.sh root@imx8mpevk:/# cp /unit_tests/memtool /mnt/fat/ root@imx8mpevk:/# umount /mnt/fat/ root@imx8mpevk:/# ntfs-3g /dev/sda1 /mnt/fat/ root@imx8mpevk:/# ls /mnt/fat/ README  System Volume Information  gpu.sh  gpuinfo.sh  memtool root@imx8mpevk:/#   3.exFAT is not supported on this BSP..   L6.1.22(you can check it on L5.15 and above, should be the same) You can enable ntfs support in kernel config as below, full features can be supported. > File systems > DOS/FAT/EXFAT/NT Filesystems   Pls use ‘-t ntfs3’ during mounting, otherwise it will be mounted as ‘read-only’ Log: root@imx8ulpevk:~# mount -t ntfs3 /dev/sda1 /mnt/fat/ root@imx8ulpevk:~# ls /mnt/fat/ 111.png   Image_org  'System Volume Information' root@imx8ulpevk:~# root@imx8ulpevk:~# cp gpuinfo.sh /mnt/fat/ root@imx8ulpevk:~# umount /mnt/fat/ root@imx8ulpevk:~# root@imx8ulpevk:~# mount -t ntfs3 /dev/sda1 /mnt/fat/ root@imx8ulpevk:~# ls /mnt/fat/ 111.png   Image_org  'System Volume Information'   gpuinfo.sh root@imx8ulpevk:~#   exFAT has been supported in L6.1.22. > File systems > DOS/FAT/EXFAT/NT Filesystems   /dev/sda1 on /run/media/sda1 type exfat (rw,relatime,fmask=0022,dmask=0022,iocharset=utf8,errors=remount-ro) root@imx8ulpevk:~# ls /run/media/sda1 'Certificate of Completion.pdf'             carlife.MP4 Image_org                                  example.tflite L5.4.70_2.3.0                              mx8mp_vpu.txt NXP-5G.mp4                                 sd.mp4 'System Volume Information'                 vela.ini android_p9.0.0_2.1.0-auto-ga_image_8qmek root@imx8ulpevk:~# ls Image_org  gpuinfo.sh root@imx8ulpevk:~# cp gpuinfo.sh /run/media/sda1/ root@imx8ulpevk:~# umount /run/media/sda1 root@imx8ulpevk:~#

1.Test environment Board: i.MX8MPlus, RM67199 BSP: uboot 2022.04, linux-6.1.1-1.0.1 2.Modification of uboot  In uboot, you need comment the video_link_shut_down and dm_remove_devices_flags in announce_and_cleanup function. #if defined(CONFIG_VIDEO_LINK) //video_link_shut_down(); #endif board_quiesce_devices(); printf("\nStarting kernel ...%s\n\n", fake ? "(fake run for tracing)" : ""); /* * Call remove function of all devices with a removal flag set. * This may be useful for last-stage operations, like cancelling * of DMA operation or releasing device internal buffers. */ // #ifndef CONFIG_POWER_DOMAIN // dm_remove_devices_flags(DM_REMOVE_ACTIVE_ALL | DM_REMOVE_NON_VITAL); // /* Remove all active vital devices next */ // dm_remove_devices_flags(DM_REMOVE_ACTIVE_ALL); // #endif cleanup_before_linux(); }  After doing this, the uboot logo will not be cleaned before Linux PM framework. 3.Modification of Linux You need add  CONFIG_LOGO=n into defconfig file to disable kernel logo.  3.1 Disable the power down of mediamix and mipi-dphy in gpcv2.c Please add below code into the beginning of  imx_pgc_power_down function if ((strcmp(genpd->name, "mipi-phy1") == 0) || (strcmp(genpd->name, "mediamix") == 0)) { return 0; }  3.2 Only reset lcdif in the last call of drm framework Please modify imx_lcdifv3_runtime_resume function like this. The imx_lcdifv3_runtime_resume function will be called two times, thus the lcdif will be reset two times.We can let it only reset last time,which before the rootfs mount. bool rst = false; ////////////////////////////// static int imx_lcdifv3_runtime_resume(struct device *dev) { int ret = 0; struct lcdifv3_soc *lcdifv3 = dev_get_drvdata(dev); if (unlikely(!atomic_read(&lcdifv3->rpm_suspended))) { dev_warn(lcdifv3->dev, "Unbalanced %s!\n", __func__); return 0; } if (!atomic_dec_and_test(&lcdifv3->rpm_suspended)) return 0; /* set LCDIF QoS and cache */ if (of_device_is_compatible(dev->of_node, "fsl,imx93-lcdif")) regmap_write(lcdifv3->gpr, 0xc, 0x3712); request_bus_freq(BUS_FREQ_HIGH); ret = lcdifv3_enable_clocks(lcdifv3); if (ret) { release_bus_freq(BUS_FREQ_HIGH); return ret; } ////////////////////////////// if (rst) { /* clear sw_reset */ writel(CTRL_SW_RESET, lcdifv3->base + LCDIFV3_CTRL_CLR); rst = false; } rst = true; ////////////////////////////// /* enable plane FIFO panic */ lcdifv3_enable_plane_panic(lcdifv3); return ret; } 4.Conclusion The uboot logo will be cleaned at log "imx-drm 1.0.0 20120507 for display-subsystem on minor 1". The boot time of  systemd service on evk is very long. For weston.service, it needs 3 seconds. From log here we test, the pcie and ethernet probe after drm system also cost about 1 second. If you want to reduce the boot time of other modules, you can try to reduce the system service and disable pcie/ethernet drivers if you don't need them. [ 2.505616] [drm] Initialized imx-drm 1.0.0 20120507 for display-subsystem on minor 1 [ 2.620324] imx6q-pcie 33800000.pcie: iATU unroll: enabled [ 2.620335] imx6q-pcie 33800000.pcie: iATU regions: 4 ob, 4 ib, align 64K, limit 16G [ 2.720689] imx6q-pcie 33800000.pcie: PCIe Gen.1 x1 link up [ 2.820996] imx6q-pcie 33800000.pcie: PCIe Gen.2 x1 link up [ 2.821003] imx6q-pcie 33800000.pcie: Link up, Gen2 [ 2.821010] imx6q-pcie 33800000.pcie: PCIe Gen.2 x1 link up [ 2.821112] imx6q-pcie 33800000.pcie: PCI host bridge to bus 0000:00 [ 2.821119] pci_bus 0000:00: root bus resource [bus 00-ff] [ 2.821126] pci_bus 0000:00: root bus resource [io 0x0000-0xffff] [ 2.821133] pci_bus 0000:00: root bus resource [mem 0x18000000-0x1fefffff] [ 2.821161] pci 0000:00:00.0: [16c3:abcd] type 01 class 0x060400 [ 2.821176] pci 0000:00:00.0: reg 0x10: [mem 0x00000000-0x000fffff] [ 2.821187] pci 0000:00:00.0: reg 0x38: [mem 0x00000000-0x0000ffff pref] [ 2.821232] pci 0000:00:00.0: supports D1 [ 2.821237] pci 0000:00:00.0: PME# supported from D0 D1 D3hot D3cold [ 2.824664] pci 0000:01:00.0: [1b4b:2b42] type 00 class 0x020000 [ 2.824725] pci 0000:01:00.0: reg 0x10: [mem 0x00000000-0x000fffff 64bit pref] [ 2.824761] pci 0000:01:00.0: reg 0x18: [mem 0x00000000-0x000fffff 64bit pref] [ 2.825066] pci 0000:01:00.0: supports D1 D2 [ 2.825072] pci 0000:01:00.0: PME# supported from D0 D1 D3hot D3cold [ 2.835499] pci 0000:00:00.0: BAR 0: assigned [mem 0x18000000-0x180fffff] [ 2.835511] pci 0000:00:00.0: BAR 15: assigned [mem 0x18100000-0x182fffff pref] [ 2.835519] pci 0000:00:00.0: BAR 6: assigned [mem 0x18300000-0x1830ffff pref] [ 2.835530] pci 0000:01:00.0: BAR 0: assigned [mem 0x18100000-0x181fffff 64bit pref] [ 2.835561] pci 0000:01:00.0: BAR 2: assigned [mem 0x18200000-0x182fffff 64bit pref] [ 2.835590] pci 0000:00:00.0: PCI bridge to [bus 01-ff] [ 2.835598] pci 0000:00:00.0: bridge window [mem 0x18100000-0x182fffff pref] [ 2.835899] pcieport 0000:00:00.0: PME: Signaling with IRQ 218 [ 2.897767] Console: switching to colour frame buffer device 135x120 [ 3.098361] imx-drm display-subsystem: [drm] fb0: imx-drmdrmfb frame buffer device [ 3.111239] pps pps0: new PPS source ptp0 [ 3.316650] fec 30be0000.ethernet eth0: registered PHC device 0 [ 3.323645] imx-dwmac 30bf0000.ethernet: IRQ eth_lpi not found [ 3.329593] imx-dwmac 30bf0000.ethernet: force_sf_dma_mode is ignored if force_thresh_dma_mode is set. [ 3.340074] imx-dwmac 30bf0000.ethernet: User ID: 0x10, Synopsys ID: 0x51 [ 3.346883] imx-dwmac 30bf0000.ethernet: DWMAC4/5 [ 3.351684] imx-dwmac 30bf0000.ethernet: DMA HW capability register supported [ 3.358825] imx-dwmac 30bf0000.ethernet: RX Checksum Offload Engine supported [ 3.365966] imx-dwmac 30bf0000.ethernet: Wake-Up On Lan supported [ 3.372113] imx-dwmac 30bf0000.ethernet: Enable RX Mitigation via HW Watchdog Timer [ 3.379778] imx-dwmac 30bf0000.ethernet: Enabled L3L4 Flow TC (entries=8) [ 3.386573] imx-dwmac 30bf0000.ethernet: Enabled RFS Flow TC (entries=10) [ 3.393373] imx-dwmac 30bf0000.ethernet: Enabling HW TC (entries=256, max_off=256) [ 3.400950] imx-dwmac 30bf0000.ethernet: Using 34 bits DMA width [ 3.608045] xhci-hcd xhci-hcd.1.auto: xHCI Host Controller [ 3.613580] xhci-hcd xhci-hcd.1.auto: new USB bus registered, assigned bus number 1 [ 3.621621] xhci-hcd xhci-hcd.1.auto: hcc params 0x0220fe6d hci version 0x110 quirks 0x0000002001010010 [ 3.631059] xhci-hcd xhci-hcd.1.auto: irq 226, io mem 0x38200000 [ 3.637197] xhci-hcd xhci-hcd.1.auto: xHCI Host Controller [ 3.642698] xhci-hcd xhci-hcd.1.auto: new USB bus registered, assigned bus number 2 [ 3.650365] xhci-hcd xhci-hcd.1.auto: Host supports USB 3.0 SuperSpeed [ 3.657695] hub 1-0:1.0: USB hub found [ 3.661473] hub 1-0:1.0: 1 port detected [ 3.665669] usb usb2: We don't know the algorithms for LPM for this host, disabling LPM. [ 3.674445] hub 2-0:1.0: USB hub found [ 3.678220] hub 2-0:1.0: 1 port detected [ 3.683428] imx-cpufreq-dt imx-cpufreq-dt: cpu speed grade 7 mkt segment 2 supported-hw 0x80 0x4 [ 3.693184] Hot alarm is canceled. GPU3D clock will return to 64/64 [ 3.702683] sdhci-esdhc-imx 30b50000.mmc: Got CD GPIO [ 3.703346] mxc-mipi-csi2-sam 32e40000.csi: supply mipi-phy not found, using dummy regulator [ 3.716645] : mipi_csis_imx8mp_phy_reset, No remote pad found! [ 3.722602] mxc-mipi-csi2-sam 32e40000.csi: lanes: 2, hs_settle: 13, clk_settle: 2, wclk: 1, freq: 500000000 [ 3.739353] mmc1: SDHCI controller on 30b50000.mmc [30b50000.mmc] using ADMA [ 3.752018] isi-m2m 32e00000.isi:m2m_device: Register m2m success for ISI.0 [ 3.759172] cfg80211: Loading compiled-in X.509 certificates for regulatory database [ 3.768303] cfg80211: Loaded X.509 cert 'sforshee: 00b28ddf47aef9cea7' [ 3.787598] platform regulatory.0: Direct firmware load for regulatory.db failed with error -2 [ 3.795171] ALSA device list: [ 3.796227] platform regulatory.0: Falling back to sysfs fallback for: regulatory.db [ 3.799186] No soundcards found. [ 3.819630] EXT4-fs (mmcblk2p2): mounted filesystem with ordered data mode. Quota mode: none. [ 3.828212] VFS: Mounted root (ext4 filesystem) on device 179:2. [ 3.834944] devtmpfs: mounted

  Introduction   Prior to 6.1.22_2.0.0 BSP release, Bluetooth interface are based on the tty line discipline framework, so we need to use hciattach tool to enable it in the user space. From 6.1.22_2.0.0 BSP, the nxp bluetooth driver no longer needs the help of the userspace hciattach tool, and the tty port bound by bluetooth also won't be exported to the user space, so you cannot find the corresponding tty device anymore. So, you won't see the (/dev/ttymxcX), for the Bluetooth interface. All jobs has been done in the new NXP Bluetooth driver. New Method   The new NXP Bluetooth UART Driver is based on a server driver for the NXP BT serial protocol, which can enable the built-in Bluetooth device inside an NXP BT chip. This driver has a Power Save feature that will put the chip into a sleep state whenever there is no activity for 2000ms and will be woken up when any activity is to be initiated over UART.  Device Tree support The new BT framework requires adding a "bluetooth" sub node with a device compatibility string to the attached UART node in the dts file &uart1 { bluetooth { compatibility = "nxp,88w8987-bt"; fw-init-baudrate = <3000000>; #Optional. Default is considered 115200 if this parameter not defined. }; };   Note: The parameter ‘compatibility = “nxp,88w8987-bt”’ will use for 88W8987, IW416, 88Q9098, IW612 chipsets and need to change for 88W8997 with parameter ‘compatibility = “nxp,88w8997-bt”’.   Note: ’fw-init-baudrate’ parameter depends on the module vendor. The Murata and Azuere wifi modules support in BSP release uses the default value -- 115200. We strongly recommend looking at the module vendor-specific baud rate parameter. Note: For the old 88Q9098 Murata 1XL module that uses the 3Mbps by default, please add the fw-init-baudrate = <3000000> property in dts files to make it work. Enable Guide   Use wifi interface to load combo (wifi & bt) firmware and enable BT Need to load wifi driver first, then load the BT driver, otherwise, BT driver suspend/resume test will fail. This is a HW limitation, since NXP wifi and BT module use the same power control pin(W_DISABLE1#), if we don't load the wifi driver, SDIO bus will power down the wifi chip during suspend resume, which may cause the BT chip also been powered down and cannot work after resume back. So we need to load the wifi driver to make sure SDIO bus won't power down the BT chip to make sure BT functions can work during suspend resume. modprobe moal mod_para=nxp/wifi_mod_para.conf modprobe btnxpuart or insmod mlan.ko insmod moal.ko mod_para=nxp/wifi_mod_para.conf insmod btnxpuart   Unload UART Driver modprobe moal Make sure run hciconfig hci0 up or hciconfig hci0 reset or bluetootctl power on before unload btnxpuart driver. If we don't open hci0 interface, the driver cannot send change to 115200 baud rate command to BT chip, which causes the host and BT chip baud rate mismatch, the host still uses 115200bps talk to the BT chip which now use 3Mbps, it cannot work anymore. So we need to make sure open the hci0 interface before unload btnxpuart driver.   mod_para=nxp/wifi_mod_para.conf modprobe btnxpuart sleep 3 hciconfig hci0 up #Note: Need to up hci interface before unload the BT module hcitool -i hci0 cmd 3F 23 02 00 00 modprobe -r btnxpuart modprobe -r moal sleep 3​ For better reference: Please find the I.MX 8MQ Linux getting started user guide, UM11483, Chapter "7.1 Bring-up using NXP Bluetooth UART driver"  Bluetooth Deep Sleep Feature App Note AN13920, Chapter 6 Load NXP UART driver module NOTE: Please do not run the power save feature for Murata IW612 2EL Module Regards, Mario

GUI Guider version: 1.6.0 LVGL version: v8.3.5 Host software requirements: Ubuntu 20.04, Ubuntu 22.04 or Debian 12 Hardware requirements: Evaluation Kit for the i.MX 93 Applications Processor. (i.MX 93 Evaluation Kit | NXP Semiconductors) On this guide we will use the IMX-MIPI-HDMI accessory board to connect the iMX93 with a HDMI Monitor. (IMX-MIPI-HDMI Product Information|NXP) This board is usually provided with the iMX8M Mini and the iMX8M Nano.  Steps: 1. Copy your project from the folder GUI-Guider-Projects to your Linux PC.  2. Build an image for iMX93 using The Yocto Project.    a. Based on iMX Yocto Porject Users Guide set directories and download the repo $ mkdir imx-bsp-6.1.1-1.0.0 $ cd imx-bsp-6.1.1-1.0.0 $ repo init -u https://github.com/nxp-imx/imx-manifest -b imx-linux-langdale -m imx-6.1.1-1.0.0.xml $ repo sync Use distro fsl-imx-xwayland and select machine imx93evk and use this commnad with a build folder name: $ MACHINE=imx93evk DISTRO=fsl-imx-xwayland source ./imx-setup-release.sh - b bld-imx93evk b. Use bitbake command to start the build process. Also, add the -c populate_sdk to get the toolchain. $ bitbake imx-image-multimedia -c populate_sdk  c. Install the Yocto toolchain located on <build-folder>/tmp/deploy/sdk/.  $ sudo sh ./fsl-imx-xwayland-glibc-x86_64-imx-image-multimedia-armv8a-imx93evk-toolchain-6.1-langdale.sh d. Install ninja utility on the build host $ sudo apt install ninja-build e. For Ubuntu 20.04 and Ubuntu 22.04, copy the lv_conf.h file from lvgl-simulator to lvgl $ cp lvgl-simulator/lv_conf.h lvgl/ f. Change the interpreter on build.sh from #!/bin/sh to #!/bin/bash. This is an important step! g. Then, enter to linux folder and use the following commands to make build.sh executable $ dos2unix build.sh $ chmod +x build.sh h. Execute the build.sh $ ./build.sh i. Copy the binary to the iMX93 using a USB or SCP.  2. On the target iMX93 follow these steps. a. On Uboot, use fatls interface device:partition fatls mmc 0:1 (Device 0 : Partition 1) With this command, we will be able to list device tree files. => fatls mmc 0:1 b. Select imx93-11x11-evk-rm67199.dtb and use the command editenv fdtfile  => editenv fdtfile Output example edit: imx93-11x11-evk-rm67199.dtb c. In edit command line put the selected device tree .dtb d. Use saveenv command to save environment and continue with the boot process. e. Finally, run the GUI Application $ ./gui_guider&   I hope this article will be helpful. Best regards, Brian.

In some cases, such as mass production or preparing a demo. We need u-boot environment stored in demo sdcard mirror image.  Here is a way: HW:  i.MX8MP evk SW:  LF_v5.15.52-2.1.0_images_IMX8MPEVK.zip The idea is to use fw_setenv to set the sdcard mirror as the operation on a real emmc/sdcard. Add test=ABCD in u-boot-initial-env for test purpose. And use fw_printenv to check and use hexdump to double confirm it. The uboot env is already written into sdcard mirror(imx-image-multimedia-imx8mpevk.wic). All those operations are on the host x86/x64 PC. ./fw_setenv -c fw_env.config -f u-boot-initial-env Environment WRONG, copy 0 Cannot read environment, using default ./fw_printenv -c fw_env.config Environment OK, copy 0 jh_root_dtb=imx8mp-evk-root.dtb loadbootscript=fatload mmc ${mmcdev}:${mmcpart} ${loadaddr} ${bsp_script}; mmc_boot=if mmc dev ${devnum}; then devtype=mmc; run scan_dev_for_boot_part; fi arch=arm baudrate=115200 ...... ...... ...... splashimage=0x50000000 test=ABCD usb_boot=usb start; if usb dev ${devnum}; then devtype=usb; run scan_dev_for_boot_part; fi vendor=freescale hexdump -s 0x400000 -n 2000 -C imx-image-multimedia-imx8mpevk.wic 00400000 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................| hexdump -s 0x400000 -n 10000 -C imx-image-multimedia-imx8mpevk.wic 00400000 5f a4 9b 97 20 6a 68 5f 72 6f 6f 74 5f 64 74 62 |_... jh_root_dtb| 00400010 3d 69 6d 78 38 6d 70 2d 65 76 6b 2d 72 6f 6f 74 |=imx8mp-evk-root| 00400020 2e 64 74 62 00 20 6c 6f 61 64 62 6f 6f 74 73 63 |.dtb. loadbootsc| 00400030 72 69 70 74 3d 66 61 74 6c 6f 61 64 20 6d 6d 63 |ript=fatload mmc| 00400040 20 24 7b 6d 6d 63 64 65 76 7d 3a 24 7b 6d 6d 63 | ${mmcdev}:${mmc| 00400050 70 61 72 74 7d 20 24 7b 6c 6f 61 64 61 64 64 72 |part} ${loadaddr| 00400060 7d 20 24 7b 62 73 70 5f 73 63 72 69 70 74 7d 3b |} ${bsp_script};| 00400070 00 20 6d 6d 63 5f 62 6f 6f 74 3d 69 66 20 6d 6d |. mmc_boot=if mm| ...... ...... ...... 00401390 76 3d 31 00 73 6f 63 3d 69 6d 78 38 6d 00 73 70 |v=1.soc=imx8m.sp| 004013a0 6c 61 73 68 69 6d 61 67 65 3d 30 78 35 30 30 30 |lashimage=0x5000| 004013b0 30 30 30 30 00 74 65 73 74 3d 41 42 43 44 00 75 |0000.test=ABCD.u| 004013c0 73 62 5f 62 6f 6f 74 3d 75 73 62 20 73 74 61 72 |sb_boot=usb star| 004013d0 74 3b 20 69 66 20 75 73 62 20 64 65 76 20 24 7b |t; if usb dev ${| 004013e0 64 65 76 6e 75 6d 7d 3b 20 74 68 65 6e 20 64 65 |devnum}; then de| flash the sdcard mirror into i.MX8MP evk board emmc to check uuu -b emmc_all imx-boot-imx8mp-lpddr4-evk-sd.bin-flash_evk imx-image-multimedia-imx8mpevk.wic  The first time boot, the enviroment is already there.  How to achieve that: a. fw_setenv/fw_printenv: https://github.com/sbabic/libubootenv.git Note: Please do not use uboot fw_setenv/fw_printenv Compile it on the host x86/x64 PC. It is used on host. b. u-boot-initial-env Under uboot, make u-boot-initial-env Note: Yocto deploys u-boot-initial-env by default c. fw_env.config  imx-image-multimedia-imx8mpevk.wic 0x400000 0x4000 0x400000 0x4000 are from uboot-imx\configs\imx8mp_evk_defconfig CONFIG_ENV_SIZE=0x4000 CONFIG_ENV_OFFSET=0x400000 Now, you can run  ./fw_setenv -c fw_env.config -f u-boot-initial-env