APPLIED Re: [PATCH 0/6][SRU][OEM-6.0] both dell_backlight and nvidia_0 backlight interface appear, and can't adjust the display brightness

[Timo Aaltonen]

AceLan Kao kirjoitti 27.4.2023 klo 10.41:
> From: "Chia-Lin Kao (AceLan)" <acelan.kao at canonical.com>
> 
> BugLink: https://launchpad.net/bugs/2017774
> 
> [Impact]
> When switched to discrete mode in the BIOS, nvidia driver will create its
> own backlight interface(nvidia_0) to control the backlight, but at the
> same time dell-laptop creates its own backlight interface(dell_backlight),
> too. In discrete mode, dell_backlight interface doesn't work, and it leads
> to gnome chooses the wrong interface(dell_backlight) to control the
> backlight and then leads to the issue.
> 
> [Fix]
> The acpi_video_backlight_use_native() helper function is introduced after
> v6.1 and nvidia driver will call this function if kernel provides it. This
> helper tells video_detect module that nvidia controls the backlight, so
> that dell-laptop won't create another backlight interface when it's loaded
> 
> Below commits are all from v6.1-rc1
> fb1836c91317 ACPI: video: Prefer native over vendor
> a5df42521f32 ACPI: video: Simplify __acpi_video_get_backlight_type()454d61a56d5e ACPI: video: Make acpi_video_backlight_use_native() always return true
> b39be9f441f9 ACPI: video: Refactor acpi_video_get_backlight_type() a bit
> a2fc3c899bb0 ACPI: video: Drop backlight_device_get_by_type() call from acpi_video_get_backlight_type()
> 2600bfa3df99 ACPI: video: Add acpi_video_backlight_use_native() helper
> 
> [Test]
> Verified on the target machine and confirmed dell_backlight interface is
> not generated.
> 
> [Where problem could occur]
> All changes are in __acpi_video_get_backlight_type() function and to make
> it smarter to decide which type of backlight interface should be created.
> The final result is pretty similar to the latest mainline version, if it
> introduce any regression we can add quirk to list those misjudged machines.
> 
> Hans de Goede (6):
>    ACPI: video: Add acpi_video_backlight_use_native() helper
>    ACPI: video: Drop backlight_device_get_by_type() call from
>      acpi_video_get_backlight_type()
>    ACPI: video: Refactor acpi_video_get_backlight_type() a bit
>    ACPI: video: Make acpi_video_backlight_use_native() always return true
>    ACPI: video: Simplify __acpi_video_get_backlight_type()
>    ACPI: video: Prefer native over vendor
> 
>   drivers/acpi/video_detect.c | 58 ++++++++++++++++++++++++++-----------
>   include/acpi/video.h        |  5 ++++
>   2 files changed, 46 insertions(+), 17 deletions(-)
> 

Turns out this was already applied for -1016, but I didn't send this 
email after applying it, whoops..


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