[Freedreno] [v3 0/2] drm: Add support for backlight control of eDP panel on ti-sn65dsi86 bridge

[Rajeev Nandan]

The backlight level of an eDP panel can be controlled through the AUX
channel using DPCD registers of the panel.

The capability for the Source device to adjust backlight characteristics
within the panel, using the Sink device DPCD registers is indicated by
the TCON_BACKLIGHT_ADJUSTMENT_CAPABLE bit in the EDP_GENERAL_CAPABILITY_1
register (DPCD Address 701h, bit0). In this configuration, the eDP TCON
receives the backlight level information from the host, through the AUX
channel.

Anderson's patch series [1] exposed the DDC bus from ti-sn65dsi86 bridge,
that gives an option to move the backlight control out of the bridge and
to create a separate backlight driver.

Changes in v2:
- Created a new DisplayPort aux backlight driver and moved the code from
  drm_dp_aux_backlight.c (v1) to the new driver.
- Removed the changes done in ti-sn65dsi86 bridge. (Rob Herring)

Changes in v3:
- Add missing ';' to fix module compilation (kernel test bot)

[1] https://lore.kernel.org/dri-devel/20210416223950.3586967-1-dianders@chromium.org/

Rajeev Nandan (2):
  dt-bindings: backlight: add DisplayPort aux backlight
  backlight: Add DisplayPort aux backlight driver

 .../bindings/leds/backlight/dp-aux-backlight.yaml  |  49 +++++
 drivers/video/backlight/Kconfig                    |   7 +
 drivers/video/backlight/Makefile                   |   1 +
 drivers/video/backlight/dp_aux_backlight.c         | 245 +++++++++++++++++++++
 4 files changed, 302 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/leds/backlight/dp-aux-backlight.yaml
 create mode 100644 drivers/video/backlight/dp_aux_backlight.c

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2.7.4