NACK/Cmnt[G]: [PATCH 0/1][SRU][F][G][H][OEM-5.10] XPS 9510 (TGL) Screen

[Stefan Bader]

On 25.06.21 04:13, AceLan Kao wrote:
> From: "Chia-Lin Kao (AceLan)" <acelan.kao at canonical.com>
> 
> BugLink: https://bugs.launchpad.net/bugs/1933566
> 
> [Impact]
> Dell XPS 15 9510(TGL) uses DPCD to control backlight, and need to add this
> panel to edid_quirk.
> 
> kernel: [ 1.719773] i915 0000:00:02.0: [drm] Panel advertises DPCD
> backlight support, but VBT disagrees. If your backlight controls don't work
> try booting with i915.enable_dpcd_backlight=1. If your machine needs this,
> please file a _new_ bug report on drm/i915, see
> https://gitlab.freedesktop.org/drm/intel/-/wikis/How-to-file-i915-bugs for
> details.
> 
> Kernel 5.12+ support the backlight via:
> commit: <4a8d79901d5b> ("drm/i915/dp: Enable Intel's HDR backlight
> interface (only SDR for now)"), and doesn't need this quirk.
> 
> [Fix]
> Adding the panel's MFG to edid_quirk makes system switch to use DPCD to
> control backlight.
> 
> [Test]
> Verified on Dell XPS 9510(TGL)
> 
> [Where problems could occur]
> The quirk is for a dedicate panel, and won't affect other platforms.
> 
> Chia-Lin Kao (AceLan) (1):
>    UBUNTU: SAUCE: drm/i915: Force DPCD backlight mode for Dell XPS
>      9510(TGL)
> 
>   drivers/gpu/drm/drm_dp_helper.c | 1 +
>   1 file changed, 1 insertion(+)
> 
Groovy is EOL next week.

-Stefan

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