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182d0ba6d6
Update the Anbernic RGxx3 documentation to note that panel detection has been added and how it works. Signed-off-by: Chris Morgan <macromorgan@hotmail.com> Reviewed-by: Kever Yang <kever.yang@rock-chips.com>
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56 lines
2 KiB
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.. SPDX-License-Identifier: GPL-2.0+
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U-Boot for Anbernic RGxx3 Devices
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=================================
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This allows U-Boot to boot the following Anbernic devices:
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- Anbernic RG353M
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- Anbernic RG353P
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- Anbernic RG353PS
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- Anbernic RG353V
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- Anbernic RG353VS
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- Anbernic RG503
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The correct device is detected automatically by comparing ADC values
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from ADC channel 1. In the event of an RG353V or RG353P, an attempt
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is then made to probe for an eMMC and if it fails the device is assumed
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to be an RG353VS or RG353PS. Based on the detected device, the
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environment variables "board", "board_name", and "fdtfile" are set to
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the correct values corresponding to the board which can be read by a
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boot script to boot with the correct device tree. If the board detected
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is not of type RG503 (which currently has only 1 panel revision) a
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panel detect is then performed by probing a "dummy" display on the DSI
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bus and then querying the display ID. The display ID is then compared
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to a table to get the known compatible string for use in Linux, and
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this string is saved as an environment variable of "panel".
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FDT fixups are performed in the event of an RG353M to change the device
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name, or in the event the panel detected does not match the devicetree.
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This allows Linux to load the correct panel driver without having to
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know exactly which panel is used (as there is no user distingushable
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way to tell).
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Building U-Boot
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---------------
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.. code-block:: bash
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$ export CROSS_COMPILE=aarch64-linux-gnu-
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$ export BL31=../rkbin/bin/rk35/rk3568_bl31_v1.34.elf
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$ export ROCKCHIP_TPL=../rkbin/bin/rk35/rk3568_ddr_1056MHz_v1.13.bin
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$ make anbernic-rgxx3_defconfig
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$ make
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This will build ``u-boot-rockchip.bin`` which can be written to an SD
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card.
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Image installation
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------------------
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Write the ``u-boot-rockchip.bin`` to an SD card offset 32kb from the
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start. Please note that eMMC booting has not been tested at this time.
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.. code-block:: bash
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$ dd if=u-boot-rockchip.bin of=/dev/mmcblk0 bs=512 seek=64
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