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[0/1,SRU,G] UBUNTU: SAUCE: Fix brightness control on BOE 2270 panel

Message ID 20201210081644.293291-1-aaron.ma@canonical.com
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Series UBUNTU: SAUCE: Fix brightness control on BOE 2270 panel | expand

Message

Aaron Ma Dec. 10, 2020, 8:16 a.m. UTC 
BugLink: https://bugs.launchpad.net/bugs/1904991

[Impact]
BOE 2270 panel is used by several models of ThinkPads.
This brightness can not be controlled by default PWM.

[Fix]
The panel claims both PWM and AUX supports.
But actually PWM works on SDR mode, AUX works on HDR mode.
Intel i915 driver got a new SDR support to use PWM by maintainer, still
in upstream review.
To fix this on certain project, use a quirk first to fix this.
The maintainer's fix can be backported in future.

[Test Case]
Backlight brightness can be changed.

[Regression Potential]
The BOE 2270 backlight brightness can not be changed.
Fix for specific panel ID, no effects for others.
Send it to groovy, oem-5.6 already got one.

Aaron Ma (1):
  UBUNTU: SAUCE: drm/i915: Force DPCD backlight mode for BOE 2270 panel

 drivers/gpu/drm/drm_dp_helper.c | 1 +
 1 file changed, 1 insertion(+)

Comments

Stefan Bader Dec. 17, 2020, 7:34 a.m. UTC | #1 
On 10.12.20 09:16, Aaron Ma wrote:
> BugLink: https://bugs.launchpad.net/bugs/1904991
> 
> [Impact]
> BOE 2270 panel is used by several models of ThinkPads.
> This brightness can not be controlled by default PWM.
> 
> [Fix]
> The panel claims both PWM and AUX supports.
> But actually PWM works on SDR mode, AUX works on HDR mode.
> Intel i915 driver got a new SDR support to use PWM by maintainer, still
> in upstream review.
> To fix this on certain project, use a quirk first to fix this.
> The maintainer's fix can be backported in future.
> 
> [Test Case]
> Backlight brightness can be changed.
> 
> [Regression Potential]
> The BOE 2270 backlight brightness can not be changed.
> Fix for specific panel ID, no effects for others.
> Send it to groovy, oem-5.6 already got one.
> 
> Aaron Ma (1):
>   UBUNTU: SAUCE: drm/i915: Force DPCD backlight mode for BOE 2270 panel
> 
>  drivers/gpu/drm/drm_dp_helper.c | 1 +
>  1 file changed, 1 insertion(+)
> 
This is just for clarity as Ian's message sent about this, at least for me, ends
up in a previous thread of this.

-Stefan