Hi Akihiko,

On 10/24/22 13:34, Akihiko Odaki wrote:

Commit 2600bfa3df99 ("ACPI: video: Add acpi_video_backlight_use_native()
helper") and following commits made native backlight unavailable if
CONFIG_ACPI_VIDEO is set and the backlight feature of ACPI video is
unavailable, which broke the backlight functionality on Lenovo ThinkPad
C13 Yoga Chromebook. Allow to fall back to native backlight in such
cases.

I appreciate your work on this, but what this in essence does is
it allows 2 backlight drivers (vendor + native) to get registered
for the same panel again. While the whole goal of the backlight refactor
series landing in 6.1 was to make it so that there always is only
*1* backlight device registered instead of (possibly) registering
multiple and letting userspace figure it out. It is also important
to only always have 1 backlight device per panel for further
upcoming changes.

So nack for this solution, sorry.

I am aware that this breaks backlight control on some Chromebooks,
this was already reported and I wrote a long reply explaining why
things are done the way they are done now and also suggesting
2 possible (much simpler) fixes, see:
https://lore.kernel.org/linux-acpi/42a5f2c9-a1dc-8fc0-7334-fe6c390ecfbb@redhat.com/ (local)

Unfortunately the reported has not followed-up on this and
I don't have the hardware to test this myself.

Can you please try implementing 1 of the fixes suggested there
and then submit that upstream ?

Regards,

Hans

Signed-off-by: Akihiko Odaki <redacted>

Akihiko Odaki (22):
  drm/i915/opregion: Improve backlight request condition
  ACPI: video: Introduce acpi_video_get_backlight_types()
  LoongArch: Use acpi_video_get_backlight_types()
  platform/x86: acer-wmi: Use acpi_video_get_backlight_types()
  platform/x86: asus-laptop: Use acpi_video_get_backlight_types()
  platform/x86: asus-wmi: Use acpi_video_get_backlight_types()
  platform/x86: compal-laptop: Use acpi_video_get_backlight_types()
  platform/x86: eeepc-laptop: Use acpi_video_get_backlight_types()
  platform/x86: fujitsu-laptop: Use acpi_video_get_backlight_types()
  platform/x86: ideapad-laptop: Use acpi_video_get_backlight_types()
  platform/x86: msi-laptop: Use acpi_video_get_backlight_types()
  platform/x86: msi-wmi: Use acpi_video_get_backlight_types()
  platform/x86: nvidia-wmi-ec-backlight: Use
    acpi_video_get_backlight_types()
  platform/x86: panasonic-laptop: Use acpi_video_get_backlight_types()
  platform/x86: samsung-laptop: Use acpi_video_get_backlight_types()
  platform/x86: sony-laptop: Use acpi_video_get_backlight_types()
  platform/x86: thinkpad_acpi: Use acpi_video_get_backlight_types()
  platform/x86: toshiba_acpi: Use acpi_video_get_backlight_types()
  platform/x86: dell-laptop: Use acpi_video_get_backlight_types()
  platform/x86: intel_oaktrail: Use acpi_video_get_backlight_types()
  ACPI: video: Remove acpi_video_get_backlight_type()
  ACPI: video: Fallback to native backlight

 Documentation/gpu/todo.rst                    |  8 +--
 drivers/acpi/acpi_video.c                     |  2 +-
 drivers/acpi/video_detect.c                   | 54 ++++++++++---------
 drivers/gpu/drm/i915/display/intel_opregion.c |  3 +-
 drivers/platform/loongarch/loongson-laptop.c  |  4 +-
 drivers/platform/x86/acer-wmi.c               |  2 +-
 drivers/platform/x86/asus-laptop.c            |  2 +-
 drivers/platform/x86/asus-wmi.c               |  4 +-
 drivers/platform/x86/compal-laptop.c          |  2 +-
 drivers/platform/x86/dell/dell-laptop.c       |  2 +-
 drivers/platform/x86/eeepc-laptop.c           |  2 +-
 drivers/platform/x86/fujitsu-laptop.c         |  4 +-
 drivers/platform/x86/ideapad-laptop.c         |  2 +-
 drivers/platform/x86/intel/oaktrail.c         |  2 +-
 drivers/platform/x86/msi-laptop.c             |  2 +-
 drivers/platform/x86/msi-wmi.c                |  2 +-
 .../platform/x86/nvidia-wmi-ec-backlight.c    |  2 +-
 drivers/platform/x86/panasonic-laptop.c       |  2 +-
 drivers/platform/x86/samsung-laptop.c         |  2 +-
 drivers/platform/x86/sony-laptop.c            |  2 +-
 drivers/platform/x86/thinkpad_acpi.c          |  4 +-
 drivers/platform/x86/toshiba_acpi.c           |  2 +-
 drivers/video/backlight/backlight.c           | 18 +++++++
 include/acpi/video.h                          | 21 ++++----
 include/linux/backlight.h                     |  1 +
 25 files changed, 85 insertions(+), 66 deletions(-)