### System details

GPU: AMD Radeon RX 9070 XT, Monitor: ASUS ROG Swift PG278Q via displayport

### What's wrong?

# ASUS ROG Swift PG278Q detected as 640x480 only on RX 9070 XT (EDID read failure)

This is my first ever bug report, and a fix for it. I just wanted to share the solution so other people can skip the debugging headache. I have no idea if this is unique to Omarchy, or Arch overall.

## Description

On Omarchy, my ASUS ROG Swift PG278Q was detected only as a 640x480 display on an AMD Radeon RX 9070 XT. The same monitor, GPU, cable, and PC worked correctly on CachyOS.

## Symptoms

* Hyprland showed the monitor as DP-1/DP-3 with empty make/model fields.
* The only available mode was `[email protected]`.
* Running:

```bash
journalctl -b | grep -i edid
```

produced:

```text
[drm:dm_helpers_read_local_edid [amdgpu]] *ERROR* EDID err: 2, on connector: DP-3
amdgpu 0000:0a:00.0: [drm] *ERROR* No EDID read.
```

## Hardware

* GPU: AMD Radeon RX 9070 XT
* Monitor: ASUS ROG Swift PG278Q
* Connection: DisplayPort
* Kernel: 7.0.9-arch2-1

## Possible Cause

The monitor EDID was not read correctly by amdgpu on Omarchy. The PG278Q is an older G-Sync monitor and appears to have EDID/DDC compatibility issues on some Linux setups.

## Fix

I dumped a working EDID file from an OS where the monitor works:

```bash
sudo cat /sys/class/drm/card*-DP-*/edid > PG278Q.bin
```

Then copied it into the firmware directory:

```bash
sudo mkdir -p /usr/lib/firmware/edid
sudo cp PG278Q.bin /usr/lib/firmware/edid/PG278Q.bin
```

The important Omarchy-specific part was that kernel parameters needed to be added to:

```text
/etc/default/limine
```

and not only to:

```text
/etc/kernel/cmdline
```

or

```text
/boot/limine.conf
```

I added the following to the relevant `KERNEL_CMDLINE[default]` line:

```text
drm.edid_firmware=DP-1:edid/PG278Q.bin video=DP-1:e
```

Then rebuilt the UKI:

```bash
sudo limine-mkinitcpio
```

Alternatively:

```bash
sudo mkinitcpio -P
```

and accept the prompt to run `limine-mkinitcpio`.

## Result

After rebooting into the default Omarchy entry, `/proc/cmdline` included the EDID override and the monitor worked correctly at its native resolution and refresh rate.