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Update amdgpu pixel format post

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Wesley Moore 2021-05-15 10:23:05 +10:00
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v2/content/posts/2020/linux-amdgpu-pixel-format.md
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@ -3,7 +3,7 @@ title = "Setting the amdgpu HDMI Pixel Format on Linux"
date = 2020-05-30T08:48:30+10:00 date = 2020-05-30T08:48:30+10:00
[extra] [extra]
updated = 2020-06-02T08:15:44+10:00 updated = 2021-05-15T10:15:08+10:00
+++ +++
This week I discovered some details of digital display technology that I was This week I discovered some details of digital display technology that I was
@ -93,19 +93,34 @@ Now we need to get the kernel to use the modified file:
1. `sudo mkdir /lib/firmware/edid` 1. `sudo mkdir /lib/firmware/edid`
1. `sudo mv edid.bin /lib/firmware/edid/edid.bin` 1. `sudo mv edid.bin /lib/firmware/edid/edid.bin`
1. Edit the kernel command line. I use [systemd-boot], so I edited `/boot/loader/entries/arch.conf` and added `drm_kms_helper.edid_firmware=edid/edid.bin` to the command line, making the full file look like this: 1. Edit the kernel command line. I use [systemd-boot], so I edited
`/boot/loader/entries/arch.conf` and added
`drm.edid_firmware=HDMI-A-1:edid/edid.bin` to the command line, making the
full file look like this:
title Arch Linux title Arch Linux
linux /vmlinuz-linux linux /vmlinuz-linux
initrd /amd-ucode.img initrd /amd-ucode.img
initrd /initramfs-linux.img initrd /initramfs-linux.img
options root=PARTUUID=2f693946-c278-ed44-8ba2-67b07c3b6074 resume=UUID=524c0604-c307-4106-97e4-1b9799baa7d5 resume_offset=4564992 drm_kms_helper.edid_firmware=edid/edid.bin rw options root=PARTUUID=2f693946-c278-ed44-8ba2-67b07c3b6074 resume=UUID=524c0604-c307-4106-97e4-1b9799baa7d5 resume_offset=4564992 drm.edid_firmware=HDMI-A-1:edid/edid.bin rw
**Note 1:** `HDMI-A-1` is the connector to apply the EDID firmware to. It
was determined from the `/sys` path above:<br>
<code>/sys/devices/pci0000:00/0000:00:03.1/0000:09:00.0/drm/card0/card0-<b>HDMI-A-1</b>/edid</code>
**Note 2:** Older kernels (before 4.15 I think) used
`drm_kms_helper.edid_firmware` as the command line argument instead of
`drm.edid_firmware`.
1. Regenerate the initial RAM disk: `sudo mkinitcpio -p linux` 1. Regenerate the initial RAM disk: `sudo mkinitcpio -p linux`
1. Reboot 1. Reboot
After rebooting the display confirmed it was now using RGB and visually it was After rebooting the display confirmed it was now using RGB and visually it was
looking much brighter! 🤞 the display blanking issue remains fixed as well. looking much brighter! 🤞 the display blanking issue remains fixed as well. You
can also check the that kernel applied the firmware by looking at the kernel
log (`dmesg`) for a line like:
[ 4.956349] [drm] Got external EDID base block and 1 extension from "edid/edid.bin" for connector "HDMI-A-1"
[P2415Q]: https://www.dell.com/en-au/shop/dell-24-ultra-hd-4k-monitor-p2415q/apd/210-anfp/monitors-monitor-accessories [P2415Q]: https://www.dell.com/en-au/shop/dell-24-ultra-hd-4k-monitor-p2415q/apd/210-anfp/monitors-monitor-accessories
[ryzen9-pc]: https://bitcannon.net/page/ryzen9-pc/ [ryzen9-pc]: https://bitcannon.net/page/ryzen9-pc/