Re: [PATCH v3 0/8] Add support for a DRM backlight capability

[Louis Chauvet <louis.chauvet@bootlin.com>]

On 4/25/26 00:09, Mario Limonciello wrote:
> From: Mario Limonciello (AMD) <superm1@kernel.org>
> 
> At Display Next Hackfest 2025 we discussed the renewed need for moving
> brightness control into the DRM connector properties.  I've taken the
> previous efforts from David and Marta, rebased and adjusted for the
> current kernel.
> 
> The legacy sysfs interface is synchronized with the DRM connector (although
> the scale may be different as DRM connector property is u16).
> 
> Later after this has been adopted by enough userspace, it may make sense to
> configure the legacy sysfs interface to be configurable so that only
> DRM master controls backlight.
> 
> I've done a first implementation with amdgpu with eDP connectors; but
> conceivably this can be extended to other connectors like DP for displays
> that can be controlled via DDC as well later.
> 
> I have also used DRM review prompts to review this series and fix some bugs
> which were caught with two different Claude models.  The fixes are squashed
> into the patches.
> 
> Assisted-by: Claude Opus
> Assisted-by: Claude Sonnet
> 
> For ease of testing; this series is also available on this branch:
> https://git.kernel.org/pub/scm/linux/kernel/git/superm1/linux.git/log/?h=superm1/backlight-property-v3

Hello,

thanks for this work, I am very interested in this progress so I can 
help you to test / implement more features.

I think you forgot to include the revert of "backlight: Remove notifier" 
in your series, it can't be applied without it.

I will take a look and see if I can create a VKMS implementation of your 
work.

Thanks for this work,

> David Rheinsberg (1):
>    backlight: add kernel-internal backlight API
> 
> Mario Limonciello (6):
>    drm: link connectors to backlight devices
>    DRM: Add support for client and driver indicating support for
>      luminance
>    drm/amd/display: Pass up errors reading actual brightness
>    drm/amd: Indicate driver supports luminance
>    drm/amd/display: Allow backlight registration to fail
>    drm/amd/display: use drm backlight
> 
> Marta Lofstedt (1):
>    backlight: expose the current brightness in the new kernel API
> 
>   drivers/gpu/drm/Kconfig                       |   1 +
>   drivers/gpu/drm/Makefile                      |   2 +
>   drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c       |   1 +
>   .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c |  88 +++-
>   drivers/gpu/drm/drm_atomic_uapi.c             |  24 ++
>   drivers/gpu/drm/drm_backlight.c               | 406 ++++++++++++++++++
>   drivers/gpu/drm/drm_connector.c               |  12 +
>   drivers/gpu/drm/drm_drv.c                     |   8 +
>   drivers/gpu/drm/drm_ioctl.c                   |  10 +
>   drivers/gpu/drm/drm_mode_config.c             |   7 +
>   drivers/gpu/drm/drm_mode_object.c             |  66 ++-
>   drivers/gpu/drm/drm_sysfs.c                   |  54 +++
>   drivers/video/backlight/backlight.c           |  83 ++++
>   include/drm/drm_backlight.h                   |  45 ++
>   include/drm/drm_connector.h                   |   8 +
>   include/drm/drm_drv.h                         |   7 +
>   include/drm/drm_file.h                        |   8 +
>   include/drm/drm_mode_config.h                 |   5 +
>   include/linux/backlight.h                     |  30 ++
>   include/uapi/drm/drm.h                        |  10 +
>   20 files changed, 852 insertions(+), 23 deletions(-)
>   create mode 100644 drivers/gpu/drm/drm_backlight.c
>   create mode 100644 include/drm/drm_backlight.h
>