Rock Bullseye HDMI EDID file

#1

Hi group, I have to use an edid.dat file for my tv.
On RPI4 bullseye I copy it to /lib/firmware and drm.edid_firmware=edid.dat -> cmdline.txt, haven’t worked yet on Rock4C+
I have correct modeline and Prefered Mode in Xorg.conf and when X starts at least the TV X Screen switches on/off in correct resolution and picture, seems like something having no edid is fighting against something just using the modeline.

#2

We’re working with the Rock 4SE, so your mileage may vary. Also I am far from expert but may be able to provide some hints.

  1. Verify the kernel has CONFIG_DRM_LOAD_EDID_FIRMWARE=y
    grep CONFIG_DRM_LOAD_EDID /boot/config-5.10.110-1-rockchip
    CONFIG_DRM_LOAD_EDID_FIRMWARE=y
  2. Copy the edid bin file to firmware
    sudo cp edid.bin /lib/firmware/edid/
  3. Create initramfs edid hook
    sudo tee<<__EOF /etc/initramfs-tools/hooks/edid >/dev/null
    #!/bin/sh
    PREREQ=""
    prereqs()
    {
    echo “$PREREQ”
    }
    case $1 in

    get pre-requisites

    prereqs)
    prereqs
    exit 0
    ;;
    esac
    . /usr/share/initramfs-tools/hook-functions
    copy_exec /lib/firmware/edid/*.bin
    __EOF
    sudo chmod +x /etc/initramfs-tools/hooks/edid
  4. Update ramdisk
    sudo update-initramfs –u
  5. Update linux command line for boot. In our case it’s done like this
    edit /etc/kernel/cmdline to add the extra arguments. Again for us it looks like (yours would clearly be different)
    drm.edid_firmware=HDMI-A-1:edid/edid.bin video=HDMI-A-1:480x1280@60
    sudo u-boot-update
  6. Reboot and verify command line
    cat /proc/cmdline

Clearly you’ll want to have a copy of your sd card in case this bricks your device. And again, these instructions were passed on to us from someone who understands the process, but that’s not me. I can offer no further insight but only wish you good luck!

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