Asus Zenbook UX5406AA Display Backlight Fix

[mateuszkowalczyk]

Problem

ASUS Zenbook UX5406AA (Panther Lake) has broken brightness control (adjusting brightness does not affect actual brightness). This seems to be the same issue as the one on ExpertBook fixed in #5435

Solution

Extract backlight fix from ExpertBook B9406 solution into a separate script and run it for both ExpertBook and new Zenbook UX5406AA.

Migration

Adds a migration that:

• Runs only for the models mentioned above.
• Removes the old xe.enable_dpcd_backlight=1 entry from the ExpertBook-specific drop-in if the file exists.
• Applies the new shared ASUS Panther Lake backlight drop-in.
• Runs limine-update.

Future Models

Other ASUS Panther Lake models may need the same fix, but this only enables it for confirmed ExpertBook B9406 and Zenbook UX5406AA hardware for now. Once we have evidence that other models are affected we can easily extend the list of included models.

Testing

• I didn't perform the fresh install of Omarchy, but ran the fix script manually on my Zenbook while simulating the installation environment variables instead.
• I removed the fix, then ran the migration directly to test it.
• I force-ran the existing ExpertBook script from Add ASUS ExpertBook B9406 display and touchpad fixes for Panther Lake #5435 on my Zenbook by removing the if condition, then ran the migration to verify the upgrade path from the existing fix file.

Code Review

• I double-checked it myself and asked GPT-5.5 on OpenCode for review in terms of correctness and consistency with Omarchy source code
• @mijuny - I'd appreciate it if you could test the migration on your ExpertBook to make sure it works on a real device. I'd also appreciate a quick review of my changes, since they build upon your fixes.

[Copilot]

Pull request overview

This PR factors the xe.enable_dpcd_backlight=1 kernel-cmdline workaround into a shared ASUS Panther Lake backlight script and applies it to both the existing ExpertBook B9406 and the new Zenbook UX5406AA hardware match, with an upgrade migration to transition existing installs.

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Changes:

• Add a shared ASUS Panther Lake display backlight fix drop-in script and run it during install.
• Introduce Zenbook UX5406AA hardware detection.
• Add a migration to remove the old ExpertBook-specific backlight entry and rebuild Limine entries.

Reviewed changes

Copilot reviewed 4 out of 5 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
migrations/1777938402.sh	Migration to transition ExpertBook + enable shared backlight fix for supported ASUS PTL models.
install/config/hardware/asus/fix-asus-ptl-display-backlight.sh	New shared script writing the Limine entry-tool drop-in for xe.enable_dpcd_backlight=1.
install/config/hardware/asus/fix-asus-ptl-b9406-display.sh	Removes the backlight knob from the B9406-specific display workaround (keeps Panel Replay fix).
install/config/all.sh	Runs the new shared ASUS PTL backlight fix during install.
bin/omarchy-hw-asus-zenbook-ux5406aa	Adds HW match helper for Zenbook UX5406AA on Intel Panther Lake.

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[Copilot]

Pull request overview

Copilot reviewed 4 out of 5 changed files in this pull request and generated no new comments.

[dhh]

cc @mijuny could you verify if this all still works fine on the expertbook?

[mijuny]

Hi!

I tested the migration on B9406 (PR HEAD 9acc40b2, ran with OMARCHY_PATH pointed at the branch checkout to mirror omarchy-migrate's invocation).

Pre-migration drop-in had both flags. Post-migration: dpcd line correctly sed'd out of asus-expertbook-b9406-display.conf with panel-replay line preserved. New asus-ptl-display-backlight.conf has xe.enable_dpcd_backlight=1.

Aggregated /boot/limine.conf shows both flags exactly once per entry.

After reboot, /proc/cmdline carries both flags. Brightness works normally/smoothly across the range and no Panel Replay regression. omarchy-hw-asus-zenbook-ux5406aa correctly returns false on B9406. Looks good.