LX2160ARDB - How to update Linux kernel and device tree on SD card

[#1]

Follow these steps to update the Linux kernel image and device tree for LX2160ARDB on an SD card. 

NOTE: Below steps are valid for both LX2160ARDB Rev 1.0 and Rev 2.0 revisions.

STEP 1: Compiling Linux kernel images and device tree

1. On Linux host, clone the repository with Linux kernel image and device tree:

   $ git clone https://source.codeaurora.org/external/qoriq/qoriq-components/linux

2. $ cd linux
3. $ git checkout -b <new branch> <start point>

   • For example, $ git checkout -b LSDK-20.04-V5.4 LSDK-20.04-V5.4

     where LSDK-20.04-V5.4 refers to a tag in the format LSDK-<LSDK version>-V<kernel version>
4. $ make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- defconfig lsdk.config

   If you want to make changes to the device tree, open and edit arch/arm64/boot/dts/freescale/fsl-lx2160a-rdb.dts

5. $ make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu-

The binary kernel image Image and compressed kernel image Image.gz are in arch/arm64/boot/.
The device tree blob fsl-lx2160a-rdb.dtb is in arch/arm64/boot/dts/freescale/.

STEP2: Copying the compiled kernel images and device tree to the SD card

1. Plug the SD card into the Linux host machine.
2. sudo fdisk -l to list the disks that are accessible to the computer.
3. Mount the SD card partition that contains Linux kernel images and device tree.
   1. sudo mkdir <mount_location>
   2. sudo mount /dev/sdX <mount_location>

   For example:

   $ sudo mkdir /carddata

   $ sudo mount /dev/mmcblk0p2 /carddata

   NOTE:

   • Use the command cat /proc/partitions to see the list of devices, their partitions along with their sizes to make sure that the correct device and partition name have been chosen.
   • The eMMC storage drive in the Linux PC is detected as /dev/sdX, where X is a letter such as a, b, c. Make sure to choose the correct device name, because data on this device will be replaced.
   • If your Linux host machine supports read/write SD card directly without an extra SD card reader device, the device name of SD card is typically mmcblk0.
   • In general, the Linux kernel images and device tree are stored in the second partition of the SD device (mmcblk0p2). For detail on storage layout on SD/eMMC/USB/SATA for LSDK images deployment, refer to section "LSDK memory layout and Userland" in

     Layerscape Software Development Kit User Guide.

4. Replace Image, Image.gz, and fsl-lx2160a-rdb.dtb on the SD card with the new files compiled in the steps above.

   $ sudo cp /linux/arch/arm64/boot/Image /linux/arch/arm64/boot/Image.gz /linux/arch/arm64/boot/dts/freescale/fsl-lx2160a-rdb.dtb <mount_location>

   For example: $sudo cp /linux/arch/arm64/boot/Image /linux/arch/arm64/boot/Image.gz /linux/arch/arm64/boot/dts/freescale/fsl-lx2160a-rdb.dtb /carddata
5. Unmount the card. For example: sudo umount /dev/mmcblk0p2
6. Plug the SD card into LX2160ARDB and boot the board.
• At U-Boot, run the following command to boot the board to LSDK distro using the SD card.

=> run bootcmd_mmc0

If U-Boot does not find LSDK on the SD card, it will boot TinyDistro from lsdk_linux_arm64_ tiny.itb stored on the SD card.