ThinkPad T14 Gen 1 AMD switching to lowest brightness during boot process with 5.14-rc2

[Martin Steigerwald]

Not subscribed, so please Cc on answer.

Hi!

Just compiled 5.14-rc2 for my T14 Gen 1 AMD with "AMD Ryzen 7 PRO 4750U 
with Radeon Graphics" with Low Power Display (400 Nits).

Using that kernel, the display starts with the usual high brightness. 
However, during boot the brightness goes down to what appears to be the 
minimum. In KDE Plasma however the brightness of the display is shown as 
maximum.

If I move around the brightness slider just a few percent down from 100 
to maybe 98% or something like that the brightness is immediately reset 
to its actual value display by the slider.

This did not happen with 5.13.

I am still on X11 as some KDE Plasma features are not yet available for 
Wayland.

This is on Devuan Ceres – basically Debian Sid without Systemd – with 
Runit as init system, so there no automatic Systemd brightness logic 
should be involved.

If attached kernel configuration is stripped, please let me know.

Best,
-- 
Martin
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