ACK: [PATCH 0/1][SRU][L][M] Various backlight issues with the 6.0/6.1 kernel

Tim Gardner tim.gardner at
Wed Jul 5 17:27:05 UTC 2023

On 6/27/23 8:42 PM, AceLan Kao wrote:
> From: "Chia-Lin Kao (AceLan)" <acelan.kao at>
> BugLink:
> [Impact]
> There are some new patches for new method to decide which backlight driver
> should be registered introduced since 6.1. And we backport some of them to
> 6.0-oem kernel which are not enough to solved all backlight issues.
> 1. dell_laptop created a non-working backlight driver before nvidia is
>     loaded, that leads to the system can't adjust the display brightness.
> 2. acpi_backlight0 sometimes will be generated together with intel_backlight.
> [Fix]
> Below 2 commits from v6.3-rc6 prevent the acpi_backlight from being
> registered automatically(which have been included into ubuntu kernels
> through stable update)
> e506731c8f35 ACPI: video: Make acpi_backlight=video work independent from GPU driver
> 78dfc9d1d1ab ACPI: video: Add auto_detect arg to __acpi_video_get_backlight_type()
> Below patch prevents platform driver(dell_laptop) from creating backlight
> driver after win8.
> aa8a950a5d6b ACPI: video: Stop trying to use vendor backlight control on laptops from after ~2012
> [Test]
> Verified on the dell platform which reports this issue.
> [Where problems could occur]
> The assumption of the last commit regarding backlight control is that,
> after Windows 8, all laptop backlights are controlled either by ACPI or the
> native graphics driver. It impacts the laptops that do not follow the
> assumption and will lead to no backlight interface is generated. We
> don't see this case in our OEM projects for several years.
> Hans de Goede (1):
>    ACPI: video: Stop trying to use vendor backlight control on laptops
>      from after ~2012
>   drivers/acpi/video_detect.c | 21 +++++++++++++++++++++
>   1 file changed, 21 insertions(+)
Acked-by: Tim Gardner <tim.gardner at>
Tim Gardner
Canonical, Inc

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