[PATCH 0/1][SRU][F/OEM-5.6/Groovy] Fix acpi backlight issue on some thinkpads

[Aaron Ma]

BugLink: https://bugs.launchpad.net/bugs/1892010

[Impact]
On some ThinkPads, the BIOS reported invalid acpi backlight implement .
Then backlight can't be changed because OS use acpi backlight by
default.

[Fix]
Check acpi backlight mode, disable it if invalid.

[Test Case]
Verified on 3 models of thinkpad include Intel/NV/AMD GPU with positive
results.

[Regression Potential]
Low
Most ThinkPads now use native backlight control by default.
Check the false acpi mode correctly.

Aaron Ma (1):
  platform/x86: thinkpad_acpi: not loading brightness_init when _BCL
    invalid

 drivers/platform/x86/thinkpad_acpi.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

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2.25.1