Re: [REGRESSION] No physical display brightness control on kernel 7.1.x

On 7/25/26 22:04, anon wrote:
> Device model: Google Pixelbook 2017 i7 (EVE)
> OS: Fedora 44 KDE
> Kernel: 7.1.4
> Firmware: MrChromebox UEFI full ROM (https://docs.mrchromebox.tech/)
> 
> Hi. I'm experiencing an issue on the above system where adjusting
> brightness values via the DE UI doesn't affect the physical brightness
> of the display itself. The problem began following a recent system
> update.

This sounds a bit like a known problem (see
https://gitlab.freedesktop.org/drm/i915/kernel/-/work_items/16507 ) that
is fixed by a411ea4a871628 ("drm/i915/backlight: Remove
DP_EDP_BACKLIGHT_AUX_ENABLE_CAP check for DPCD backlight") [v7.2-rc5].
This likely will be backported to 7.1.y sooner or later, but if you
could confirm that applying this to 7.1.y fixes your issue then we could
speed things up by asking the stable team to pick this up.

Ciao, Thorsten

> Admittedly, I haven't done the work myself to verify that this is a
> kernel regression, though I believe it probable due to this forum
> discussion: (https://forum.chrultrabook.com/t/2017-pixelbook-backlight-control-doesnt-work-with-7-1-kernel/8954),
> the efforts of the OP in that discussion and the fact that I also own
> a Kubuntu system running kernel 7.0.x without issue.