tree 5bfd7ae3e3fe8c11858374579d20ce301e8076b8
parent a3c148955c22fe1d94d7a2096005679c1f22eddf
author Werner Sembach <wse@tuxedocomputers.com> 1666797766 +0200
committer Greg Kroah-Hartman <gregkh@linuxfoundation.org> 1667486955 +0900

ACPI: video: Force backlight native for more TongFang devices

commit 3dbc80a3e4c55c4a5b89ef207bed7b7de36157b4 upstream.

This commit is very different from the upstream commit! It fixes the same
issue by adding more quirks, rather then the general fix from the 6.1
kernel, because the general fix from the 6.1 kernel is part of a larger
refactoring of the backlight code which is not suitable for the stable
series.

As described in "ACPI: video: Drop NL5x?U, PF4NU1F and PF5?U??
acpi_backlight=native quirks" (10212754a0d2) the upstream commit "ACPI:
video: Make backlight class device registration a separate step (v2)"
(3dbc80a3e4c5) makes these quirks unnecessary. However as mentioned in this
bugtracker ticket https://bugzilla.kernel.org/show_bug.cgi?id=215683#c17
the upstream fix is part of a larger patchset that is overall too complex
for stable.

The TongFang GKxNRxx, GMxNGxx, GMxZGxx, and GMxRGxx / TUXEDO
Stellaris/Polaris Gen 1-4, have the same problem as the Clevo NL5xRU and
NL5xNU / TUXEDO Aura 15 Gen1 and Gen2:
They have a working native and video interface for screen backlight.
However the default detection mechanism first registers the video interface
before unregistering it again and switching to the native interface during
boot. This results in a dangling SBIOS request for backlight change for
some reason, causing the backlight to switch to ~2% once per boot on the
first power cord connect or disconnect event. Setting the native interface
explicitly circumvents this buggy behaviour by avoiding the unregistering
process.

Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Werner Sembach <wse@tuxedocomputers.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>