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This is a summary for the software lockup issue found in the following platform: −i.MX8/8X −Linux 4.14.98_2.3.3 Issue description: •Issue happens during the boot procedure, at the systemd stage. •The symptom of the issue: −From user perspective, the symptom varies, but mainly fall into several types: §At the console, there may be login prompt, but no response (only echo) when input user/password. Unable to login. §Some user service in systemd failed to start. E.g. weston. −When checking the task status using sysrq (w/t), many tasks, including some kernel core tasks stays in “D” (uninterruptable sleep) state. E.g. agetty, login, chvt, etc. •Kernel itself is still alive. This can be verified by triggering some drivers, such as plugin a USB device. Issue can be reproduced on MEK through long time stress. Please refer to the doc/patch attached for details.

PCIE IP on i.MX8MM and i.MX8MP is same, customer can follow PCIE test Application note to do compliance test, if eye diagram failed, they can fine turn corresponding regs below: iMX8MMRM.pdf IMX8MPRM.pdf GEN1: GEN2: Related code in kernel Phy-fsl-imx8-pcie.c (kernel-source\drivers\phy\freescale) 3794 2020/11/4 static int imx8_pcie_phy_init(struct phy *phy) { …… /* Configure TX drive level */ writel(0x2d, imx8_phy->base + 0x404); return 0; } Thanks Lambert

i.MX8 series contains internal HiFi4 DSP. It is targeted for Audio related signal processing. SOF (Sound Open Firmware) is open source audio DSP firmware, driver and SDK. This document introduces basic theory about IIR/FIR digital filters, how to design IIR/FIR digital filters and the Equalizer filters implementation by SOF. After that, the document also describes how HiFi4 DSP MAC engine accelerate the EQ filters calculation.

BSP: L5.15.5_1.0.0 Platform: i.MX8MPlus EVK 1. Parameter preparation For more parameter calculation, please refer to: https://community.nxp.com/t5/i-MX-Processors-Knowledge-Base/iMX-8M- Mini-Register-Programming-Aid-DRAM-PLL-setting/ta-p/111209 For 1866MHz LPDDR4, we need a DRAM PLL size of 933MHz. The PLL dividing parameters are: m=622,p=16,s=0, k=0. 2. Calibration and stress test with DDR Tool 2.1 Creating a test script for 1866MHz Here we copy the script from another file (e.g. 2000MHz) and modify the contents of the script. 2.2 Modify the script to adapt to 1866MHz 2.3 Download the test script After selecting the ddr script we created, click on the download button 2.4 Calibrating the stress test Set the core clock of the chip's cpu to 1.2GHz, then click the Calibration button to calibrate, then click Gen Code to generate the lpddr4_timing.c file. Set the start frequency to 1866MHz for the stress test. 2.5 Modify lpddr4_timing.c We need to modify the generated lpddr4_timing.c file to change the maximum speed to 3732MTS. 3. SPL patch After getting the correct lpddr4_timing.c file, the SPL code also needs to be modified to add support for the 933MHz DRAM PLL. diff --git a/arch/arm/mach-imx/imx8m/clock_imx8mm.c b/arch/arm/mach-imx/imx8m/clock_imx8mm.c index e39f238fdf...5622a6334e 100644 --- a/arch/arm/mach-imx/imx8m/clock_imx8mm.c +++ b/arch/arm/mach-imx/imx8m/clock_imx8mm.c @@ -55,6 +55,7 @@ static struct imx_int_pll_rate_table imx8mm_fracpll_tbl[] = { PLL_1443X_RATE(650000000U, 325, 3, 2, 0), PLL_1443X_RATE(600000000U, 300, 3, 2, 0), PLL_1443X_RATE(594000000U, 99, 1, 2, 0), + PLL_1443X_RATE(933000000U, 622, 16, 0, 0), PLL_1443X_RATE(400000000U, 400, 3, 3, 0), PLL_1443X_RATE(2660000U, 266, 3, 3, 0), PLL_1443X_RATE(167000000U, 334, 3, 4, 0), diff --git a/drivers/ddr/imx/imx8m/ddrphy_utils.c b/drivers/ddr/imx/imx8m/ddrphy_utils.c index 326b92d784..ebd005bc2b 100644 --- a/drivers/ddr/imx/imx8m/ddrphy_utils.c +++ b/drivers/ddr/imx/imx8m/ddrphy_utils.c @@ -117,6 +117,10 @@ void ddrphy_init_set_dfi_clk(unsigned int drate) dram_pll_init(MHZ(1000)); dram_disable_bypass(); break; + case 3732: + dram_pll_init(MHZ(933)); + dram_disable_bypass(); + break; case 3200: dram_pll_init(MHZ(800)); dram_disable_bypass(); 4. Test results Reference blog. DDR Tool: https://community.nxp.com/t5/i-MX-Processors-Knowledge-Base/i-MX-8M-Family-DDR-Tool-Release/ta-p/1104467 RPA: https://community.nxp.com/t5/i-MX-Processors-Knowledge-Base/i-MX-8MPlus-m865S-DDR-Register-Programming-Aids-RPA/ta-p/1235352

Hello, here Jorge. On this post I will explain how to configure, record and play audio using an i.MX 8MIC-RPI-MX8 Board. Requirements: I.MX 8M Mini EVK Linux Binary Demo Files - i.MX 8MMini EVK (L5.15.52_2.1.0) i.MX 8MIC-RPI-MX8 Board Serial console emulator (Tera Term, Putty, etc.) Headphones/speakers The 8MIC-RPI-MX8 accessory board is designed for voice enabled application prototyping and development on the i.MX 8M family. The board plugs directly into the 40-pin expansion connector on the i.MX 8M Mini and Nano EVK’s. Some features about this board are: 8 PDM Microphones 8 monochrome LEDs 4 multi-color LEDs 2 status LEDs 4 pushbuttons Microphone Mute Switch Microphone geometry switch Connecting the i.MX 8MIC-RPI-MX8 Board. The i.MX 8MIC-RPI-MX8 Board has a 40-pin expansion connector that you can plug it directly to the EVK board. Ensure that pin 1 of the 8MIC-RPI-MX8 is aligned with pin 1 on the EVK J1001 as is showed on the next figure: Selecting the device tree on the board. Once the pre-compiled image is flashed on the board (Flashing Linux BSP using UUU) and you connected the 8MIC-RPI-MX8 it is necessary to select the correct device tree to handle 8MIC board. On U-boot check the available .dtb files on the BSP using the next command: u-boot=> fatls mmc 2:1 And you will get the corresponding list of .dbt files: On this case we are working with an I.MX 8M Mini EVK and the corresponding .dtb file is: imx8mm-evk-8mic-revE.dtb To select it you need to set the environment variable and save it with: u-boot=> setenv fdtfile imx8mm-evk-8mic-revE.dtb u-boot=> saveenv Doble check it using: u-boot=> printenv fdtfile Now it is time to boot Linux using the next command: u-boot=> boot Recording audio with the i.MX 8MIC-RPI-MX8 Board. The Advanced Linux Sound Architecture (ALSA) provides audio and MIDI functionality to the Linux operating system. ALSA has the following significant features: Efficient support for all types of audio interfaces, from consumer sound cards to professional multichannel audio interfaces. Fully modularized sound drivers. SMP and thread-safe design. User space library (alsa-lib) to simplify application programming and provide higher level functionality. Support for the older Open Sound System (OSS) API, providing binary compatibility for most OSS programs. Once we are on Linux, we can check our audio codecs detected on the board using: arecord -l Now, to record audio we need to use the ALSA arecord command to start recording with IMX8 boards, there are different options that you can check on the next link. On this case we are going to use the next: arecord -D hw:imxaudiomicfil -c8 -f s16_le -r48000 -d10 sample.wav -D: selects the device. -c: selects the number of channels on the recording. -f: selects the format. -r: selects the sample rate. -d: determinate the duration recording time in seconds. sample.wav: Is the name of the resulting audio file. Running the last command, we started to record audio. It is time to make some noise and record it! Playing audio from IMX8 boards. Now it is time to connect our headphones or speakers to the jack. Also, as on arecord command you can check the devices where you can play audio from the board using the next command: aplay -l And you will get all the codecs to play audio: To play our recordings we need to use the ALSA aplay command, it is important to select the correct audio codec to hear the audio from the jack on the board: aplay -Dplughw:3,0 sample.wav -D: selects the device. sample.wav: Is the name of audio file to play Hope this will helpful for people who wants to record audio using PDM microphones and playing audio from IMX8 boards. Best regards.

Symptoms Bridge mode on EQoS module will not work since Linux Kernel 5.10_2.2.0. Platforms impacted: i.MX8MP/i.MX8DXL/i.MX93 Diagnosis When eqos module(eth1) is added to the bridge using brctl, it will first set eth1 to promiscuous mode and then set the VLAN for this bridge with a filter VID value of 1. Before adding Intel's patch, there is no problem. c89f44ff10fd net: stmmac: Add support for VLAN promiscuous mode However, when Intel's patch sets up the filter, if it finds that the promiscuous mode is turned on, it will turn off the VLAN Tag function. And it adds a judgment on whether promiscuous mode has been turned on in the function of configuring VID. Returns an error if promiscuous mode is found. Because the patch has turned off the VLAN tag function when promiscuous mode is enabled, which conflicts with continuing to configure the VID. Workaround This patch is okay for aarch64 platform to solve this issue. diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac4_core.c b/drivers/net/ethernet/stmicro/stmmac/dwmac4_core.c index c25bfecb4a2d..2dc548b54b1c 100644 --- a/drivers/net/ethernet/stmicro/stmmac/dwmac4_core.c +++ b/drivers/net/ethernet/stmicro/stmmac/dwmac4_core.c @@ -481,12 +481,6 @@ static int dwmac4_add_hw_vlan_rx_fltr(struct net_device *dev, if (vid > 4095) return -EINVAL; - if (hw->promisc) { - netdev_err(dev, - "Adding VLAN in promisc mode not supported\n"); - return -EPERM; - } - /* Single Rx VLAN Filter */ if (hw->num_vlan == 1) { /* For single VLAN filter, VID 0 means VLAN promiscuous */ @@ -536,12 +530,6 @@ static int dwmac4_del_hw_vlan_rx_fltr(struct net_device *dev, { int i, ret = 0; - if (hw->promisc) { - netdev_err(dev, - "Deleting VLAN in promisc mode not supported\n"); - return -EPERM; - } - /* Single Rx VLAN Filter */ if (hw->num_vlan == 1) { if ((hw->vlan_filter[0] & GMAC_VLAN_TAG_VID) == vid) {

This is a simple known-how for how to enable KASAN on L4.14.98 with i.MX8/8X and also a collection of related patches for fixing issues reported by KASAN. Enable KASAN: It's very simple, just enable "CONFIG_KASAN" in kernel configuration. Besides this, adjusting the kernel's loading address is also required, due to KASAN (which will alloc more memory as a "tracker" for each allocation). For e.g., on imx8qxp MEK, we need to change the kernel loadaddr in uboot: 0x80280000 --> 0xE0280000 through uboot env: setenv loadaddr 0xE0280000 After this, it supposed to be working. KASAN related patches on L4.14.98: KASAN will do detection/sanitizing for any memory allocation/access. In case of L4.14.98 on i.MX8/8X, there're several "BUG" reported by KASAN in default BSP. The attached patches are a collection for these issues. Note: not all "BUG" reported by KASAN are really bug. Most of them are just some programming rule related problems and may not really cause memory access violation.

1. Intro This document contains instructions to run run the SAI low power audio demo on the i.MX 8M Plus EVK. Here, the RPSMG to allows audio to be passed from the A53 cluster running Linux to the M7 core. The latter controls the on board WM8960 audio codec, which is connected to a 3.5 mm audio jack that allow us to play music using headphones. I will show the necessary steps to make the demo work and will add some GStreamer examples to demonstrate the demo's capabilities. TBD: update this with a nice diagram that depicts the A53 and M7 RPMSG channel. 2. Requirements Hardware MX 8M Plus EVK Headphones with 3.5 mm audio jack Type-C power supply for i.MX 8M Plus EVK Micro USB to USB adapter cable Software A recent prebuilt Linux BSP image from NXP.com ( we tested this on 5.15.35 and 5.15.5 releases) Windows 10 or Ubuntu 20.04 Workstation MCUXpresso SDK for i.MX 8M Plus ( available from: Welcome | MCUXpresso SDK Builder (nxp.com)) 3. Reference documentation for this example MCUXpresso SDK [1] Getting Started with MCUXpresso SDK for EVK-MIMX8MP Available within the MCUXpresso SDK package: \{INSTALL PATH}\SDK_X_X_X_EVK-MIMX8MP\docs [2] SAI low power audio README file Contains instructions for the SAI Low Power Audio Demo. Available within the MCUXpresso SDK package: \{INSTALL PATH}\SDK_X_X_X_EVK-MIMX8MP\boards\evkmimx8mp\demo_apps\sai_low_power_audio 4. Downloading a pre-built Linux BSP image for the i.MX 8M Plus I will make use of the prebuilt Linux Image for the i.MX 8M Plus EVK for demonstrating the demo works. At the moment of writing this time, I used the 5.15.32 release, although there are older releases like 5.10.5 that I tested and proved to work with no issues. This SAI Low Power Audio Demo shall work for other processors on the i.MX 8M family. Although specific instructions ( e.g. load address for M-core binary load) might require some adaptation. For M-core load address, please refer to the specific MCUXpresso SDK documentation for each processor. The prebuilt Linux image (5.15.32) for the i.MX 8M Plus EVK can be downloaded from here: https://www.nxp.com/webapp/Download?colCode=L5.15.32_2.0.0_MX8MP&appType=license You can download other releases from here: Embedded Linux for i.MX Applications Processors | NXP Semiconductors . Select a version and a board and select download. 5. Flashing the BSP image If you are using an Ubuntu 20.04 workstation, I recommend you to flash the image using dd. For this, you can refer to the i.MX Linux User's Guide: Section - 4.3.2 Copying the full SD card image - https://www.nxp.com/docs/en/user-guide/IMX_LINUX_USERS_GUIDE.pdf sudo dd if=.wic of=/dev/sdx bs=1M && sync NOTE: when using dd, ALWAYS, double check the of device that you are about to writing. Messing up with another location or partition will harm your system If you are following this document on a Windows machine: You can use the Universal Update Utility (UUU) to flash your image on either the board's eMMC or SD card. Document named UUU.pdf shall serve as your reference guide for further instructions and flashing examples. It is available along with UUU binary here: https://github.com/NXPmicro/mfgtools/releases Two examples are shown below for your convenience: SD card flash uuu -b sd_all bootloader rootfs.sdcard.bz2 eMMC flash uuu -b emmc_all bootloader rootfs.sdcard.bz2 uuu uuu.auto NOTE: UUU is also compatible with Ubuntu NOTE: there are other engineers who like to use BalenaEtcher for flashing their BSP images. I have tested it and works on both Ubuntu and Windows 10 machines. 6. Preparing the BSP and booting up M7 core using U-Boot I am writing this upon the instructions contained on the README file for the low power audio example [2]. Instructions ready to copy and paste will follow: Instruct U-Boot to pass to the kernel the rpmsg device tree to enable communication between the A53 cluster and the M7 one: u-boot=>setenv fdtfile imx8mp-evk-rpmsg.dtb u-boot=>saveenv Load the M7 example: u-boot=>setenv mmcargs 'setenv bootargs ${jh_clk} console=${console} root=${mmcroot} snd_pcm.max_alloc_per_card=134217728' u-boot=>saveenv Now, we need to load the M4 with the demo. Refer to [1] for further information. If running the BSP on an SD card, make sure the example binary is listed on the boot partition as follows: fatls mmc 1:1 You shall see something similar to this: imx8mp_m7_TCM_sai_low_power_audio.bin Open the serial terminal emulator for the M7. Out of the fourth ports listed when we plug the i.MX 8M Plus serial debug cable to the PC, the M7 is typically the last one listed. All the serial ports available to the workstation when the i.MX 8M Plus serial cable is connected to it. NOTE: you may require to install addtitional COM drivers if you are running on Windows. I like doing the previous step so I can see the result of the next commands issued in U-boot to load the M7 image. fatload mmc 1:1 0x48000000 imx8mp_m7_TCM_sai_low_power_audio.bin; cp.b 0x48000000 0x7e0000 20000; bootaux 0x7e0000 Here is an screenshot that shows how the U-Boot's response should look: U-Boot response when loading the SAI low power audio example to the Cortex M7 That should have prompted the following message on the M7 terminal: M7-core is up! Now, let’s move to user space! u-boot=> boot 7. Testing the example using a simple GStreamer pipeline As soon as the O.S. finishes booting. We can see that M7 terminal prompts the following: M7 is now in STOP mode; waiting for some audio to beat the room! Confirm that the WM8960 is listed as audio card as follows: cat /proc/asound/cards Listing avaialable audio cards. WM8960 should be present. Make note of the list. The wm8960 is listed a the third sound card. This is where I like to differ a bit from [2] and I suggest a quicker test in case of not having an audio file ready. We just simply use GStreamer to play an audiotest source. Please make sure to plug in your headphones onto the board’s 3.5 mm jack before. The following GStreamer pipeline is using the WM8960 as an audiosink. gst-launch-1.0 audiotestsrc ! alsasink device=hw:3 NOTE: please be cautious and not put the headphones directly in your head at the first attempt. The sound can be too loud to some people. This is what you should see on the M7 side: Stop the GStreamer pipeline issuing CTRL + C. M7 shall warn you about that: NOTE: you can use the aplay command to play audio as shown on [2]. However, I consider using a testsrc is much quicker and flexible for a quick test. 8. Additional information Feel free to go ahead and tweak the GStreamer pipeline to change audio test source properties. audiotest src. This command will let you know the available options: gst-inspect-1.0 audiotestsrc NOTE: you can navigate through the displayed list using the “d”key. Press “q’’ to quit. For example: For example, I am reproducing sound using a different setup based on the list above: gst-launch-1.0 audiotestsrc freq=4000 volume=0.8 wave=8 ! alsasink device=hw:3 9. Errata and future updates TBD: Add an example on how to define the default audio card and play the audio either using gst-play or building the pipeline using filesrc Comment on the limitations of the M7 core regarding sample rate and audio formats

BSP: L5.15.5_1.0.0 Platform: i.MX8MPlus EVK Background The function lpddr4_mr_read in BSP always return zero and this casue the customer can't use it to read MR registers in DRAM. This is a simple demo for reading MR registers. Patch Code diff --git a/arch/arm/include/asm/arch-imx8m/ddr.h b/arch/arm/include/asm/arch-imx8m/ddr.h index 0f1e832c03..fd68996a23 100644 --- a/arch/arm/include/asm/arch-imx8m/ddr.h +++ b/arch/arm/include/asm/arch-imx8m/ddr.h @@ -721,6 +721,8 @@ int wait_ddrphy_training_complete(void); void ddrphy_init_set_dfi_clk(unsigned int drate); void ddrphy_init_read_msg_block(enum fw_type type); +unsigned int lpddr4_mr_read(unsigned int mr_rank, unsigned int mr_addr); + void update_umctl2_rank_space_setting(unsigned int pstat_num); void get_trained_CDD(unsigned int fsp); diff --git a/board/freescale/imx8mp_evk/spl.c b/board/freescale/imx8mp_evk/spl.c index 33bbbc09ac..85e40ffbbe 100644 --- a/board/freescale/imx8mp_evk/spl.c +++ b/board/freescale/imx8mp_evk/spl.c @@ -150,6 +150,40 @@ int board_fit_config_name_match(const char *name) return 0; } #endif +void lpddr4_get_info() +{ + int i = 0, attempts = 5; + + unsigned int ddr_info = 0; + unsigned int regs[] = { 5, 6, 7, 8 }; + + for(i = 0; i < ARRAY_SIZE(regs); i++){ + unsigned int data = 0; + data = lpddr4_mr_read(0xF,regs[i]); + ddr_info <<= 8; + ddr_info += (data & 0xFF); + switch (i) + { + case 0: + printf("DRAM INFO : Manufacturer ID = 0x%x",ddr_info); + if(ddr_info & 0Xff) + printf(", Micron\n"); + break; + case 1: + printf("DRAM INFO : Revision ID1 = 0x%x\n",ddr_info); + break; + case 2: + printf("DRAM INFO : Revision ID2 = 0x%x\n",ddr_info); + break; + case 3: + printf("DRAM INFO : I/O Width and Density = 0x%x\n",ddr_info); + break; + default: + break; + } + } + +} void board_init_f(ulong dummy) { @@ -187,6 +221,8 @@ void board_init_f(ulong dummy) /* DDR initialization */ spl_dram_init(); + + lpddr4_get_info(); board_init_r(NULL, 0); } diff --git a/drivers/ddr/imx/imx8m/ddrphy_utils.c b/drivers/ddr/imx/imx8m/ddrphy_utils.c index 326b92d784..f45eeaf552 100644 --- a/drivers/ddr/imx/imx8m/ddrphy_utils.c +++ b/drivers/ddr/imx/imx8m/ddrphy_utils.c @@ -194,8 +194,15 @@ unsigned int lpddr4_mr_read(unsigned int mr_rank, unsigned int mr_addr) tmp = reg32_read(DRC_PERF_MON_MRR0_DAT(0)); } while ((tmp & 0x8) == 0); tmp = reg32_read(DRC_PERF_MON_MRR1_DAT(0)); - tmp = tmp & 0xff; reg32_write(DRC_PERF_MON_MRR0_DAT(0), 0x4); + + while (tmp) { //try to find a significant byte in the word + if (tmp & 0xff) { + tmp &= 0xff; + break; + } + tmp >>= 8; + } return tmp; } Test Result

This is simple known-how for how to implement "boot animation" with DRM under i.MX8/X + Linux: Code to refer to: ========================================================================= 1. kmscube: Either open source one or the customized on for i.MX will be OK: https://cgit.freedesktop.org/mesa/kmscube/ https://source.codeaurora.org/external/imx/kmscube-imx/ 2. Android display HAL: KmsDisplay.cpp Known-how: ========================================================================= 1. Only one application can grab the master role of the DRM device. If need to control DRM from two applicaiton simultanously, possible solution: A, Use "controlD" node instead of "card" node in /dev/dri/. This requires L4.14 or before. This device node was removed by two commits in L4.14.x: 8a357d10043c75e980e7fcdb60d2b913491564af 6449b088dd51dd5aa6b38455888bbf538d21f2fc Can be brought back by reverting these two commits in L4.14.98. B, Use framebuffer emulator to emulate a FB device (/dev/fb0). (not recommended due to lack of vsync). 2. Some kernel functions will re-config the DRM device during boot. This will cause display abnormal after user application has configured the DRM device. Better to disable these kernel features: CONFIG_DRM_FBDEV_EMULATION CONFIG_FRAMEBUFFER_CONSOLE 3. Use atomic mode of KMS API instead of legacy mode for any dynamically screen drawing application, such as video, game and etc. Atomic mode will have much better performance compare to legacy mode. The kmscube has sample code for both mode. 4. Better to do commit checking before doing any real commit, especially when doing display during boot. Sometimes some internal component in DRM is not fully ready after card device is present. DRM_MODE_ATOMIC_ALLOW_MODESET 5. If video playback will be used, some points to remind: a, Sample code for direct video decoding (in unit-test): imx-test/test/mxc_v4l2_vpu_test/ b, VPU in i.MX8/X only support tiled NV12 output and it has pixel alignment requirement (128). Need to use CPU or G2D to do un-tile, CSC and cropping. Sample code: <android>/vendor/nxp/fsl_imx_omx/OpenMAXIL/src/component/v4l2_common/G2dProcess.cpp If using G2D under Linux, it will support un-tile directly (through OpenCL internally).

This article is to show how to use CLK2 for PCIe ref clock for i.MX8MQ. Test Environment i.MX8MQ + BSP L5.10.52 Background In order to cost down, some customers used CLK2 as PCIe reference clock as below while no external OSC installed, which is different with i.MX8MQ EVK design, so no clock output for PCIe. Checked L4.14.98_2.3.0 and found it added internal PLL for PCIe clock support. Solution The attached patch based on 4.14.98 can’t be used directly on 5.10.52, the following is the main modification for PLLOUT of PCIe clock. PLLOUT Monitor Configuration Register contains bits to control the clock that will be generated on the CCM clock mapped to CLK2_P/N.

In some cases, i.MX board connect to different module. It has very tiny changes, such as just one gpio different driver strength. We can build an entire new software to handle this requirement. Here we introduce another way, using u-boot to modify the device tree(dtb) at runtime. Here is u-boot fdt command for How to use gpio-hog demo https://community.nxp.com/t5/i-MX-Processors-Knowledge-Base/How-to-use-gpio-hog-demo/ta-p/1317709 run loadfdt fdt addr ${fdt_addr_r} fdt print /soc/bus/pinctrl/uart3grp fdt rm /soc/bus/pinctrl/uart3grp fdt print serial2 fdt set serial2 status disabled fdt print serial2 fdt print gpio4 fdt resize fdt mknode gpio4 gpio_hog_demo fdt set gpio4/gpio_hog_demo gpio-hog fdt set gpio4/gpio_hog_demo gpios <7 0> fdt set gpio4/gpio_hog_demo output-high fdt print gpio4 run mmcargs run loadimage booti ${loadaddr} - ${fdt_addr_r} root@imx8mmevk:~# cat /sys/kernel/debug/gpio gpiochip0: GPIOs 0-31, parent: platform/30200000.gpio, 30200000.gpio: gpio-5 ( |PCIe DIS ) out hi gpio-13 ( |ir-receiver ) in hi IRQ ACTIVE LOW gpio-15 ( |cd ) in hi IRQ ACTIVE LOW gpiochip1: GPIOs 32-63, parent: platform/30210000.gpio, 30210000.gpio: gpio-38 ( |? ) out hi gpio-42 ( |reset ) out lo ACTIVE LOW gpio-51 ( |regulator-usdhc2 ) out lo gpiochip2: GPIOs 64-95, parent: platform/30220000.gpio, 30220000.gpio: gpio-80 ( |status ) out hi gpiochip3: GPIOs 96-127, parent: platform/30230000.gpio, 30230000.gpio: gpio-117 ( |PCIe reset ) out hi gpiochip4: GPIOs 128-159, parent: platform/30240000.gpio, 30240000.gpio: gpio-135 ( |gpio_hog_demo ) out hi gpio-141 ( |spi1 CS0 ) out hi ACTIVE LOW gpio-149 ( |wlf,mute ) out hi ACTIVE LOW root@imx8mmevk:~# [ 33.758914] VSD_3V3: disabling dtc_utils-v1.6.1-win-x86_64.zip by msys2

The following steps allow you to toggle a pin on i.MX 8M Mini EVK, you can use the EVK as not gate, trigger a wake up signal, etc. With an script and modifying the device tree you can read an input and get as output the invert input. On the Host. Cloning the Linux kernel repository. Clone the i.MX Linux Kernel repo to the home directory. cd ~ git clone -b lf-5.10.72-2.2.0 https://source.codeaurora.org/external/imx/linux-imx cd linux-imx/ Patching the device tree. Open the imx8mm-evk.dtsi file: vim arch/arm64/boot/dts/freescale/imx8mm-evk.dtsi For the purpose of this example, uart3 has to be "disabled" in order to avoid pins conflict, so change "okay" to "disabled": &uart3 { pinctrl-names = "default"; pinctrl-0 = <&pinctrl_uart3>; assigned-clocks = <&clk IMX8MM_CLK_UART3>; assigned-clock-parents = <&clk IMX8MM_SYS_PLL1_80M>; fsl,uart-has-rtscts; status = "disabled"; }; Add the following lines in the iomuxc node: &iomuxc { pinctrl-names = "default"; pinctrl-0 = <&pinctrl_hog>; pinctrl_hog: hoggrp { fsl,pins = < MX8MM_IOMUXC_ECSPI1_SS0_GPIO5_IO9 0x19 MX8MM_IOMUXC_ECSPI1_MISO_GPIO5_IO8 0x19 >; }; Build the device tree. Setup your toolchain, for example: source /opt/fsl-imx-wayland/5.10-hardknott/environment-setup-cortexa53-crypto-poky-linux Generate config file. make imx_v8_defconfig Compile the device tree. make freescale/imx8mm-evk.dtb Copy the .dtb file to the EVK, for example with scp: scp imx8mm-evk.dtb root@<EVK_IP>:/home/root Alternatively, you may copy the .dtb file directly to the FAT32 partition where the Kernel and Device Tree files are located. On the EVK Board. Switching the device tree. To copy the updated device tree to the corresponding partition, first create a directory. mkdir Partition_1 Mount the partition one. mount /dev/mmcblk1p1 Partition_1/ Copy or move the device tree into partition one. cp imx8mm-evk.dtb Partition_1/ Reboot the board. reboot Create an script. Use vi: vi toggle.sh Add the following lines: #!/bin/bash echo 136 > /sys/class/gpio/export echo in > /sys/class/gpio/gpio136/direction echo 137 > /sys/class/gpio/export echo out > /sys/class/gpio/gpio137/direction echo 0 > /sys/class/gpio/gpio137/value while : do if [[($(cat /sys/class/gpio/gpio136/value) == "0")]]; then echo 1 > /sys/class/gpio/gpio137/value else echo 0 > /sys/class/gpio/gpio137/value fi done Save the file: :wq Change file permissions: chmod +x toggle.sh Toggling a pin. In this example we are using the pin "UART3_CTS" like an input and "UART3_RTS" like an output. To toggle the pin, run the script: ./toggle.sh

i.MX Processors Knowledge Base

i.MX Processors Knowledge Base

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