Of all the i.MX serials SoC, i.MX28/i.MX6UL/i.MX7D/S use Synchronous Audio Interface(SAI) to support audio applications. SAI supports I2S, AC97, TDM and code/DSP interfaces. The SAI interface consists of these signals: SAI_MCLK         ------------  used to provide working clock for external audio device , such as audio codec. SAI_RX_BCLK  ------------  bit clock for receiving channle. SAI_RX_DATA   ------------  data of receiving channel. SAI_RX_SYNC  ------------  Frame Synchronous signal of Left and right channel for receiving channel. SAI_TX_BCLK  ------------  bit clock for transmitting channel. SAI_TX_DATA   ------------  data of transmitting channel SAI_TX_SYNC  ------------  Frame Synchronous signal of Left and right channel for transmitting channel.         According to above signals, SAI has 2 channels: receive and transmit, and these 2 channels have their own clock: bit clock and frame SYNC, so they can work independently, it means PLAY and CAPTURE can be operated simultaneously, that is to say, SAI works at Asynchronous mode this moment.        In the document, we will discuss several usages of SAI on hardware design when it works at I2S(SYNC) mode. we will take i.MX6UL as an example, and for i.MX7D/S, usages are similar. 1. IOMUX of SAI From i.MX6UL reference manual, there are 3 SAI modules in i.MX6UL: SAI1 , SAI2 & SAI3, see page 2529 in IMX6ULRM.pdf. As common applications, we will use 2 interface of SAIs. 2. Hardware connections for I2S mode Either CPU is Master or Codec is Master, hardware connections are same. (1) Single audio codec or (2) Dual audio codec (3) Audio codec + Bluetooth PCM or (4) Audio codec + Bluetooth PCM + 4G PCM or     [Note]   Attachments are schematics of WM8958 and MAX98089, which are not released by NXP, just for users who are interested in i.MX audio applications reference. If you want to use WM98089 or WM8958, please contact their manufactures and confirm if schematics are correct, so don't use them directly for your solution. NXP China TIC i.MX team Weidong Sun

  Some our customers want to use the mfgtool to download the images to QSPI and boot up. When download the demo images on our website (Linux 4.1.15) to the QSPI-NOR on IMX7D SABRE-SDB. The error occurred as follows: Is it able to program the QSPI-NOR on i.MX7D SABRE-SDB by using MFG-Tool? Answer is yes. In the above error message we can see that the system can not find and detect the qspi, so it can not excute the following code,<CMD state="body="$ flash_erase /dev/mtd0 0 20">Erasing Boot partition</CMD>Updater" type="push" when use the mfgtool to download the images to the QSPI-NOR . The board i.MX7D SABRE-SDB and default BSP are boot up from EPDC.  Here customer want to boot up from QSPI, When using QSPI, you need to de-populate R388-R391, R396-R399 and populate R392-R395, R299, R300 in your hardware. QSPI signals are muxed with EPDC_D[7:0]. You can see the schematic, details you can see as follow. After hardware modify, you can use the mfgtool2-yocto-mx-sabresd-qspi-nor-mx25l51245g.vbs to download. And then boot up from qspi, boot mode you can refer to the schematic boot up setting. Both software and mfgtool you can download here http://www.nxp.com/products/microcontrollers-and-processors/arm-processors/i.mx-applications-processors/i.mx-software-and-tools:IMXSW_HOME. Demo images can documents you can also get.    

The Linux L4.1.15_2.1.0 for i.MX 6SLL Release is now available on www.nxp.com.   Files available: # Name Description 1 fsl-yocto-L4.1.15_2.1.0-ga.tar.gz Linux BSP Documentation for L4.1.15_2.1.0. Includes Release Notes, User Guide. 2 L4.1.15_2.1.0-ga_images_MX6SLL.tar.gz i.MX 6SLL EVK Linux Binary Demo Files 3 L4.1.15_2.1.0-ga_mfg-tools.tar.gz i.MX Manufacturing Toolkit for Linux L4.1.15_2.1.0 BSP 4 imx-aacpcodec-4.2.0.tar.gz Linux AAC Plus Codec for L4.1.15_2.1.0   Target boards: i.MX 6SLL EVK Board   Features: See detail features in Release Notes   Known Issues: For known issues and more details please consult the Release Notes.   Information of release, see: README: http://git.freescale.com/git/cgit.cgi/imx/fsl-arm-yocto-bsp.git/tree/README?h=imx-4.1-krogoth ChangeLog: http://git.freescale.com/git/cgit.cgi/imx/fsl-arm-yocto-bsp.git/tree/ChangeLog?h=imx-4.1-krogoth

(   converted from discussion created by Alfred Latypov   IMX6 PCI with external cloks  )    Hello, I had a problem, to launch a board with an imx6 solo processor with a pci-express, and with external clock. I'll tell you my decision. On my motherboard there is a pci-switch PI7C9X2G606 from Pericom with 4 endpoints of Intel type 82574 ethernet controller. I used the Linux kernel version 4.9.16 In the device-tree file, I used the following options to enable external clocks for CLK1 input gate (100MHz). Sorry, I had to change the root imx6 device tree file. See attached (imx6*.dtsi) files. From ..kernel/arch/arm/boot/dts/.. Add anatop external clock source for clocks section, and change clk source for pcie-phy. ... anaclk1 {             compatible = "fixed-clock";             reg = <0>;             #clock-cells = <0>;             clock-frequency = <100000000>;  /* 100MHz */         }; ... Change pcie section ...         pcie: pcie@0x01000000 {             compatible = "fsl,imx6q-pcie", "snps,dw-pcie";             reg = <0x01ffc000 0x04000>,                   <0x01f00000 0x80000>;             reg-names = "dbi", "config";             #address-cells = <3>;             #size-cells = <2>;             device_type = "pci";             ranges = <0x81000000 0 0          0x01e00000 0 0x00100000 /* downstream I/O */                   0x82000000 0 0x01000000 0x01000000 0 0x00e00000>; /* non-prefetchable memory */             /* ranges = <0x81000000 0 0          0x01f80000 0 0x00010000                   0x82000000 0 0x01000000 0x01000000 0 0x00f00000>; */             num-lanes = <1>;             interrupts = <GIC_SPI 120 IRQ_TYPE_LEVEL_HIGH>;             interrupt-names = "msi";             #interrupt-cells = <1>;             interrupt-map-mask = <0 0 0 0x7>;             interrupt-map = <0 0 0 1 &gpc GIC_SPI 123 IRQ_TYPE_LEVEL_HIGH>,                             <0 0 0 2 &gpc GIC_SPI 122 IRQ_TYPE_LEVEL_HIGH>,                             <0 0 0 3 &gpc GIC_SPI 121 IRQ_TYPE_LEVEL_HIGH>,                             <0 0 0 4 &gpc GIC_SPI 120 IRQ_TYPE_LEVEL_HIGH>;             clocks = <&clks IMX6QDL_CLK_PCIE_AXI>,                  <&clks IMX6QDL_CLK_LVDS1_IN>,                  <&clks IMX6QDL_CLK_SATA_REF_100M>;             clock-names = "pcie", "pcie_bus", "pcie_phy";             status = "disabled";         }; ... and add new source clocks dependencies: .... &clks {         assigned-clocks = <&clks IMX6QDL_PLL6_BYPASS_SRC>,                           <&clks IMX6QDL_PLL6_BYPASS>;                                   assigned-clock-parents = <&clks IMX6QDL_CLK_LVDS1_IN>,                                  <&clks IMX6QDL_PLL6_BYPASS_SRC>;         assigned-clock-rates = <100000000>, <100000000>; }; .... for your board dtsi. I could not start the pcie-bus with the function Gen2. Next, I needed to change the bus driver (pci-imx6.c), for fine tuning the bus clock frequency. I add MPLL frequency services functions (Thanks for Charle Powe i.MX6Q: Using an external reference for PCIe 😞 ... static void imx_pcie_override_phy_mpll(struct pcie_port *pp, u32 mpll_multiplier, u32 ref_clkdiv2) {     u32 ref_usb2_en;     u32 reg1;               pr_info("Overriding PCIe PHY MPLL config: multiplier = %d, clkdiv2 = %d\n",         mpll_multiplier, ref_clkdiv2);                   // set MPLL to disabled     ////pcie_phy_write(pp->dbi_base, PCIE_PHY_MPLL_OVRD_IN_LO, 0x0001);          // set MPLL multiplier         pcie_phy_write(pp->dbi_base, PCIE_PHY_MPLL_OVRD_IN_LO,             (0x0001<<9 | (mpll_multiplier<<2)) & 0x03fc);          /*      * set the ref_clkdiv2.  when this override is enabled it      * overrides both ref_clkdiv2 and ref_usb2_en.  make sure      * the overriden ref_usb2_en reflects the original value.      */          pcie_phy_read(pp->dbi_base, PCIE_PHY_ATEOVRD, &reg1);          ref_usb2_en = (reg1 >> 1) & 0x1;        /* set the current value of ref_usb2_en as the override */          /* set the ref_clkdiv2 override  */          /* enable the ref_clkdiv2 override */          pcie_phy_write(pp->dbi_base, PCIE_PHY_ATEOVRD,             (ref_usb2_en << 1) | ref_clkdiv2 | (0x1 << 2));             /* enable MPLL */         ///pcie_phy_write(pp->dbi_base, PCIE_PHY_MPLL_OVRD_IN_LO, 0x0003);          } ... call this function in pcie_hos_init ... static void imx6_pcie_host_init(struct pcie_port *pp) {     imx6_pcie_assert_core_reset(pp);            imx6_pcie_init_phy(pp);            imx6_pcie_deassert_core_reset(pp);        imx_pcie_override_phy_mpll(pp, 50, 1); /* tune this */          dw_pcie_setup_rc(pp);     imx6_pcie_establish_link(pp);      if (IS_ENABLED(CONFIG_PCI_MSI))         dw_pcie_msi_init(pp); } ... See documentation for p.p. IMX6DLRM 50.5.1.2. Tune <pci_hotplug_mem_size> global variable for optimal pci window sizes enumeration. See for my imx6_add_pcie_port call. If you use a FEC module, it will stop working. You must use an external clock as specified in the documentation (http://cache.freescale.com/files/32bit/doc/user_guide/IMX6DQ6SDLHDG.pdf ). Changes are shown in the attached dtsi file. For clocks segment ... rmii_clk: clock@0 {             compatible = "fixed-clock";             reg = <0>;             #clock-cells = <0>;             clock-frequency = <50000000>;  /* 50MHz */         }; ... and for fec: ... fec: ethernet@02188000 {                 compatible = "fsl,imx6q-fec";                 reg = <0x02188000 0x4000>;                 interrupts-extended =                     <&intc 0 118 IRQ_TYPE_LEVEL_HIGH>,                     <&intc 0 119 IRQ_TYPE_LEVEL_HIGH>;                 clocks = <&clks IMX6QDL_CLK_ENET>,                      <&clks IMX6QDL_CLK_ENET>,                      <&rmii_clk>;                 clock-names = "ipg", "ahb", "ptp";                 status = "disabled";             }; ... If they are not required, disable this editing this file. Thanks for all. Sorry for my bad English. Alfred <[email protected]> This document was generated from the following discussion: IMX6 PCI with external cloks

  IMX6 UL boot process is described in Chapter 8 (System Boot) of the Reference Manual. Also you may look at the following Community regarding i.MX6 boot ROM activity. How to build bootable SD image (for i.MX6 SL as example)  U-boot is used as Linux bootloader and U-boot image should be located in SD area, used by i.MX6 boot ROM. The simplest way to get bootable SD card is just to copy system image in so called .sdcard format. Such image is prepared in Yocto by default and can be transfered to SD card with Linux dd command or Windows win32diskimager utility. Guide to the .sdcard format  Win32 Disk Imager download | SourceForge.net   The full SD image (.sdcard) should contain all parts, needed for Linux boot (U-boot, kernel, dtb, file system), maybe except U-boot environment. Carry out the following command to copy the SD card image to the SD/MMC card. Change sdx below to match the one used by the SD card. $ sudo dd if=<image name>.sdcard of=/dev/sdx bs=1M && sync   Note, U-boot environment (described below) should be set (and saved) in U-boot after the first start.   In any case it makes sense to understand general structure and implementation details of bootable SD card. Instructions are provided in section 4.3 (Preparing an SD/MMC card to boot) of i.MX Linux® User's Guide in Linux doc package (L4.1.15_2) http://www.nxp.com/webapp/Download?colCode=L4.1.15_2.1.0_LINUX_DOCS&Parent_nodeId=1337699481071706174845&Parent_pageType…  Summary page : i.MX 6 / i.MX 7 Series Software and Development Tool|NXP    For a Linux image to be able to run, four separate pieces are needed: • Linux OS kernel image (zImage) • Device tree file (*.dtb) • U-Boot bootloader image • Root file system (*.ext3 or *.ext4)   The mentioned files may be found in demo images on NXP Web or generated with Yocto. After a build is complete, the created image resides in <build directory>/tmp/deploy/images The device tree file (.dtb) contains board and configuration-specific changes to the kernel. Change the device tree file to change the kernel for a different i.MX board or configuration.    By default, the kernel image and DTB are located on FAT partition without a fixed raw address on the SD card. Generally fix addresses / blocks of SD card may be applied for kernel and DTB location. The users have to change the U-Boot boot environment if the fixed raw address is required. In example below the following image layout on SD card is assumed : Start address (sectors) = 0x400 bytes (2) for U-boot (i.MX6 boot ROM reads first 4K bytes of SD card). Start address (sectors) = 0xa00000 bytes (20480) for FAT partition, size=500MB, intended for Kernel zImage and DTBs. Start address (sectors) = 0x25800000 bytes (1228800) for rootfs.    Preparing the card   An SD/MMC card reader, such as a USB card reader, is required. Any Linux distribution can be used. Further follow instructions in sections 4.3.1 (Preparing the card), 4.3.3 (Partitioning the SD/MMC card), 4.3.4 (Copying a bootloader image), 4.3.5 (Copying the kernel image and DTB file), 4.3.6 Copying the root file system (rootfs) of attached "i.MX_Graphics_User's_Guide.pdf". The next step - try to insert the SD card to slot in i.MX6UL board, select proper boot options for SD boot and power the system. U-boot prompt should appear. Finally it is needed to configure environment for further Linux boot from SD. U-Boot > setenv mmcdev 1 U-Boot > setenv mmcpart 1 U-Boot > setenv mmcroot '/dev/mmcblk1p2 rootwait rw' U-Boot > setenv loadaddr 0x80800000 U-Boot > setenv fdt_addr=0x83000000 U-Boot > setenv fdt_file imx6ul-9x9-evk.dtb U-Boot > setenv mmcpart 1 U-Boot > setenv loadfdt 'fatload mmc ${mmcdev}:${mmcpart} ${fdt_addr} ${fdt_file}' U-Boot > setenv loadkernel 'fatload mmc ${mmcdev}:${mmcpart} ${loadaddr} zImage' U-Boot > setenv bootcmd 'mmc dev ${mmcdev}; run loadkernel; run mmcargs; run loadfdt; bootz $ {loadaddr} - ${fdt_addr};' U-boot > saveenv fdt_file should be set for your case ( on example “imx6ul-9x9-evk.dtb”) Try reboot with new environment.

This tutorial guides on setting up and running the NFC Demo App using the PN7120 NFC Click board with the i.MX 7Dual SABRE-SD and its mikroBUS socket compatible: MikroE NFC Click Board on i.MX7D - i.MXDev Blog

Revisions Revisions Description Details V1.0 Initial version   V1.2 Make a little update 1. Modify the path of the toolchain 2. Remove the command: make menuconfig 3. Modify the path of folder "out" in some commands   Hardware Requirement PC Host: Ubuntu for compiling, Windows for downloading and debugging Target: i.MX6ULL 14x14 EVK with LCD or HDMI TF card USB cables for console and download Power adapter Overview Ubuntu uses the same packaging management system (deb and apt) and with each development cycle pulls in the latest packages from Debian and then adapts them to Ubuntu specifics and adds more features and patches where necessary. They also push changes back to Debian and often developers are Ubuntu and Debian developers. Both of them have a nice UI and can install softwares easier than Yocto. The purpose of this doc is to install the Debian 8 Jessie Rootfs on NXP i.MX6ULL EVK Board. The doc contains several steps as following:    1. Download and compile the u-boot, kernel and dtb.    2. Get and modify the linaro rootfs.    3. Download all things to the SD card via MfgTool.    4. Run the Debian 8 Jessie in the board. Download and compile the u-boot, kernel and dtb.    a. Download the toolchain cd ~/ wget -c https://releases.linaro.org/components/toolchain/binaries/6.3-2017.02/arm-linux-gnueabihf/gcc-linaro-6.3.1-2017.02-i686_arm-linux-gnueabihf.tar.xz mkdir toolchain tar xvf gcc-linaro-6.3.1-2017.02-i686_arm-linux-gnueabihf.tar.xz -C toolchain/ --strip-components 1 export ARCH=arm export CROSS_COMPILE=../toolchain/bin/arm-linux-gnueabihf- mkdir out    b. Download and make the u-boot cd ~/ wget -c http://git.freescale.com/git/cgit.cgi/imx/uboot-imx.git/snapshot/uboot-imx-imx_v2016.03_4.1.15_2.0.0_ga.tar.bz2 mkdir uboot-imx tar jxvf uboot-imx-imx_v2016.03_4.1.15_2.0.0_ga.tar.bz2 -C uboot-imx/ --strip-components 1 cd uboot-imx make mx6ull_14x14_evk_defconfig make    c. Download and make the kernel and dtb cd ~/ wget -c http://git.freescale.com/git/cgit.cgi/imx/linux-imx.git/snapshot/linux-imx-imx_4.1.15_2.0.0_ga.tar.bz2 mkdir linux-imx tar jxvf linux-imx-imx_4.1.15_2.0.0_ga.tar.bz2 -C linux-imx/ --strip-components 1 cd linux-imx vi arch/arm/configs/imx_v7_defconfig Add a line “CONFIG_FHANDLE=y” in the file to prevent the error when boot into rootfs. ****************************************************************************** Note: If you want to use the HDMI port instead of LCD to output the screen, you should modify the file /arch/arm/boot/dts/imx6ull-14x14-evk.dts to add a child node in &i2c2 : sii902x: sii902x@39 {         compatible = "SiI,sii902x";         pinctrl-names = "default";         interrupt-parent = <&gpio2>;         interrupts = <13 IRQ_TYPE_EDGE_FALLING>;         mode_str ="1280x720M@60";         bits-per-pixel = <16>;         reg = <0x39>;         status = "okay"; }; ****************************************************************************** make imx_v7_defconfig make -j4 zImage dtbs    d. Copy the u-boot, kernel and dtb to a folder cd ~/ sudo cp uboot-imx/u-boot.imx  out/ sudo cp linux-imx/arch/arm/boot/zImage  out/ sudo cp linux-imx/arch/arm/boot/dts/imx6ull-14x14-evk.dtb  out/ Get and modify the linaro rootfs. cd ~/ wget -c https://releases.linaro.org/debian/images/alip-armhf/16.04/linaro-jessie-alip-20160428-22.tar.gz mkdir rootfs tar xvf linaro-jessie-alip-20160428-22.tar.gz -C rootfs/ --strip-components 1 cd rootfs tar jcvf linaro-jessie-alip-20160428-22.tar.bz2 ./* sudo mv linaro-jessie-alip-20160428-22.tar.bz2  ../out Now the uboot, kernel, dtb and rootfs are ready in folder ~/out/!   Download all things to the SD card via MfgTool. Download the MfgTool in: http://www.nxp.com/products/automotive-products/microcontrollers-and-processors/arm-mcus-and-mpus/i.mx-application-processors/i.mx-6-processors/sabre-board-for-smart-devices-based-on-the-i.mx-6quad-applications-processors:RD-IMX6Q-SABRE?tab=Design_Tools_Tab Select the “IMX6_L4.1.15_2.0.0_MFG-TOOL” and download. Extract “L4.1.15_2.0.0-ga_mfg-tools.tar.gz” to Windows, and then extract again the “mfgtools-with-rootfs.tar.gz” to <your path>/mfgtools/. You should rename the files in the folder ~/out/ and copy to the path <your path>/mfgtools/Profiles/Linux/OS Firmware/files/ to replace the original files: u-boot.imx -> u-boot-imx6ull14x14evk_sd.imx zImage -> zImage imx6ull-14x14-evk.dtb -> zImage-imx6ull-14x14-evk.dtb linaro-jessie-alip-20160428-22.tar.bz2 -> rootfs_nogpu.tar.bz2 Switch the SW602 in i.MX6ULL EVK board to D1: off, D2: on, insert the TF card in slot SD2 and power on the board. Connect the board with PC by two micro-USB to USB cables(one is for downloading and another is for watching log) Finally, open the script “mfgtool2-yocto-mx-evk-sdcard-sd2.vbs” in the <your path>/mfgtools/. When the “HID-compliant device” shows then click “Start”.   If the processing is done, all things have been download to the board and you can go to the next step. Run the Debian 8 Jessie in the board. The following table shows the DIP switch settings for booting from the TF slot. Switch D1 D2 D3 D4 SW601 OFF OFF ON OFF SW602 ON OFF - -   Then power on the board and the logs will show in the serial console. Debian 8 will automatic login to root. ****************************************************************************** Note: If you want to use the HDMI port instead of LCD to output the screen, you should press any key when the log: Hit any key to stop autoboot shows and change the bootargs like following example: setenv bootargs console=ttymxc0,115200 init=/init video=mxcfb0:dev=hdmi,1280x720M@60,if=RGB24,bpp=32 video=mxcfb1:off video=mxcfb2:off video=mxcfb3:off vmalloc=256M androidboot.console=ttymxc0 consoleblank=0 androidboot.hardware=freescale cma=384M saveenv ****************************************************************************** When inputting “startx &” in serial console, the alip GUI will appear in the screen.   You can also use command ”apt-get” to install softwares(E.g. Firefox as following). ****************************************************************************** Note: If you have issues with “sudo” on user UID, need to execute the following commands: root@linaro-alip:~# chown root:root /usr/bin/sudo root@linaro-alip:~# chmod 4755 /usr/bin/sudo root@linaro-alip:~# chown root:root /usr/lib/sudo/sudoers.so root@linaro-alip:~# chown root:root /etc/sudoers root@linaro-alip:~# chown root:root /etc/sudoers.d/ root@linaro-alip:~# chown root:root /etc/sudoers.d/README   Note: If you have issues with “su” from user to root, need to execute the following commands: root@linaro-alip:~# chown root:root /bin/su root@linaro-alip:~# chmod 4755 /bin/su   Note: If you want to disable the warning window “Failed to apply network settings” after executing command “startx &”, you should deactive the Bluetooth: root@linaro-alip:~# sudo systemctl stop bluetooth.service root@linaro-alip:~# sudo systemctl disable bluetooth.service ******************************************************************************

Description       this doc is explain how to develop a audio card driver base on i.MX6 platform. which explain the ASOC architecture struction basic knowledage and then give some sample for the audio driver development like: 1:NXP SGTL5000: NXP i.MX BSP sabrelite board default support it. 2: Wolfson WM8524.    A: 3.0.35 BSP support: i.MX6 setbox BSP support it:(which in elder fsl community link and out of data)    B: 3.14.28 BSP support pls check attachment: 3: Wolfson WM8960.     which include how to add the android middle-layer and driver, pls check attachment. 4: TI TLV320AIC3120      which include how to add the android middle-layer and driver, pls check attachment. 5: TI TLV320AIC3X   Products Product Category NXP Part Number URL MPU i.MX6 Family https://www.nxp.com/products/processors-and-microcontrollers/arm-processors/i-mx-applications-processors/i-mx-6-processors:IMX6X_SERIES   Tools NXP Development Board URL i.MX6 SabreSDP https://www.nxp.com/design/development-boards:EVDEBRDSSYS#/collection=softwaretools&start=0&max=25&query=typeTax%3E%3Et633::archived%3E%3E0::Sub_Asset_Type%3E%3ETSP::deviceTax%3E%3Ec731_c380_c127_c126&sorting=Buy%2FSpecifications.desc&language=en&siblings=false which have a doc MX6X_ASOC_V5-20191115.pdf and related driver sample codes.

MX6UL_Development_database_2017.4.21_V7.doc

MX7D_DDR3_压力测试应用手册_V1_201611108.doc

MX6UL_DDR3_调校_应用手册_V3_20160511.doc

MX6X_DDR3_调校_应用手册_V4_20150730.doc

MX6X_eMMC_turning_2014.11.11_V2.doc

MX6X_Uboot_V1-20130910.doc: 3.0.35: 3.0.35

i.MX6X_内核驱动代码与定制_V2-20150518.doc: 3.0.35

MX6X_3.14.28_Uboot_V1-20150917.doc

i.MX6X_3.14.28_内核驱动代码与定制_devicetree_V1-20150918.doc

Issue: kernel panic when repeating plug/unplug USB device(e.g. USB flash disk) in Linux 4.1.15 The issue is in kernel BLOCK DEVICE, this is not a hardware related issue(happens to all devices running L4.1.15 or L4.4.x), please refer to following link on kernel.org for more details and fixes: blockdev kernel regression (bugzilla 173031) - Patchwork 

The Linux L4.1.15_2.0.3 Patch for i.MX 6ULL@900MHz Release is now available on www.nxp.com. BSP Updates and Releases -> Linux -> Linux 4.1.15_2.0.3 Patch.   Files available: # Name Description 1 L4.1.15_2.0.3_6ULL_patch_images.tar.gz i.MX 6ULL-EVK@900MHz Linux Binary Demo Files   Information of release, see: README: http://git.freescale.com/git/cgit.cgi/imx/fsl-arm-yocto-bsp.git/tree/README?h=imx-4.1-krogoth ChangeLog: http://git.freescale.com/git/cgit.cgi/imx/fsl-arm-yocto-bsp.git/tree/ChangeLog?h=imx-4.1-krogoth

On L4.1.15 BSP, PWM output clock may be not stable, for example, it may switch between 200KHz and 50KHz. PWM clock source is perclk, in running mode, perclk is 24MHz, while in low power idle mode, perclk is reduced to 6MHz, so PWM output clock is reduced to 1/4. To keep PWM output stable clock, we should let perclk stay in 24MHz in low power idle mode. Attached is the patch for 6UL and 6ULL.