Re: [PATCH v2 0/3] drm: backlight quirk infrastructure and lower minimum for Framework AMD 13

[Mario Limonciello <mario.limonciello@amd.com>]

On 6/23/2024 3:51, Thomas Weißschuh wrote:
> The value of "min_input_signal" returned from ATIF on a Framework AMD 13
> is "12". This leads to a fairly bright minimum display backlight.
> 
> Add a generic quirk infrastructure for backlight configuration to
> override the settings provided by the firmware.
> Also add amdgpu as a user of that infrastructure and a quirk for the
> Framework 13 matte panel.
> Most likely this will also work for the glossy panel, but I can't test
> that.
> 
> One solution would be a fixed firmware version, but given that the
> problem exists since the release of the hardware, it has been known for
> a month that the hardware can go lower and there was no acknowledgment
> from Framework in any way, I'd like to explore this alternative
> way forward.
> 
> Notes:
> 
> * Should the quirk infrastructure be part of drm_edid.c?
> * The current allocation of struct drm_edid in amdgpu is bad.
>    But it is done the same way in other parts of amdgpu.
>    I do have patches migrating amdgpu to proper usage of struct drm_edid [0]
> 
> Mario:
> 
> I intentionally left out the consideration of the firmware version.
> The quirk will stay correct even if the firmware starts reporting
> correct values.
> If there are strong opinions it would be easy to add, though.
> 
> Based on amdgpu/drm-next.
> 
> [0] https://lore.kernel.org/lkml/20240616-amdgpu-edid-bios-v1-1-2874f212b365@weissschuh.net/
> 

Thomas,

Are you doing any testing of this lower backlight value specifically 
with panel power savings enabled?  If not can you please check that?

Specifically write the maximum value of "4" to the sysfs file:

/sys/class/drm/card0-eDP-1/amdgpu/panel_power_savings

Thanks,

> ---
> Changes in v2:
> - Introduce proper drm backlight quirk infrastructure
> - Quirk by EDID and DMI instead of only DMI
> - Limit quirk to only single Framework 13 matte panel
> - Link to v1: https://lore.kernel.org/r/20240610-amdgpu-min-backlight-quirk-v1-1-8459895a5b2a@weissschuh.net
> 
> ---
> Thomas Weißschuh (3):
>        drm: Add panel backlight quirks
>        drm: panel-backlight-quirks: Add Framework 13 matte panel
>        drm/amd/display: Add support backlight quirks
> 
>   Documentation/gpu/drm-kms-helpers.rst             |  3 +
>   drivers/gpu/drm/Kconfig                           |  4 ++
>   drivers/gpu/drm/Makefile                          |  1 +
>   drivers/gpu/drm/amd/amdgpu/Kconfig                |  1 +
>   drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 28 +++++++++
>   drivers/gpu/drm/drm_panel_backlight_quirks.c      | 76 +++++++++++++++++++++++
>   include/drm/drm_utils.h                           | 11 ++++
>   7 files changed, 124 insertions(+)
> ---
> base-commit: 1ecef5589320fd56af599b624d59c355d162ac7b
> change-id: 20240610-amdgpu-min-backlight-quirk-8402fd8e736a
> 
> Best regards,