Re: [v3 1/2] dt-bindings: backlight: add DisplayPort aux backlight

On Mon, Apr 26, 2021 at 11:29:15AM +0530, Rajeev Nandan wrote:

Add bindings for DisplayPort aux backlight driver.

Changes in v2:

• New

Signed-off-by: Rajeev Nandan rajeevny@codeaurora.org

.../bindings/leds/backlight/dp-aux-backlight.yaml | 49 ++++++++++++++++++++++ 1 file changed, 49 insertions(+) create mode 100644 Documentation/devicetree/bindings/leds/backlight/dp-aux-backlight.yaml

diff --git a/Documentation/devicetree/bindings/leds/backlight/dp-aux-backlight.yaml b/Documentation/devicetree/bindings/leds/backlight/dp-aux-backlight.yaml new file mode 100644 index 00000000..0fa8bf0 --- /dev/null +++ b/Documentation/devicetree/bindings/leds/backlight/dp-aux-backlight.yaml @@ -0,0 +1,49 @@ +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) +%YAML 1.2 +--- +$id: http://devicetree.org/schemas/leds/backlight/dp-aux-backlight.yaml# +$schema: http://devicetree.org/meta-schemas/core.yaml#

+title: DisplayPort aux backlight driver bindings

+maintainers:

• • Rajeev Nandan rajeevny@codeaurora.org

+description:

• Backlight driver to control the brightness over DisplayPort aux channel.

+allOf:

• • $ref: common.yaml#

+properties:

• compatible:
• const: dp-aux-backlight
• ddc-i2c-bus:
• $ref: /schemas/types.yaml#/definitions/phandle
• description:

•  A phandle to the system I2C controller connected to the DDC bus used
  

•  for the DisplayPort AUX channel.
  

• enable-gpios:
• maxItems: 1
• description: GPIO specifier for backlight enable pin.
• max-brightness: true

+required:

• • compatible
• • ddc-i2c-bus

+additionalProperties: false

+examples:

• • |
• backlight {

•    compatible = "dp-aux-backlight";
  

•    ddc-i2c-bus = <&sn65dsi86_bridge>;
  

•    enable-gpios = <&tlmm 12 GPIO_ACTIVE_HIGH>;
  

So the DDC bus is connected to a backlight and also a panel? This binding is not reflecting the h/w, but rather what you want for some driver.

There's only one thing here and that's an eDP panel which supports backlight control via DP aux channel. You can figure all that out from the panel's compatible and/or reading the EDID.

You might also be interested in this thread:

https://lore.kernel.org/lkml/YIKsDtjcIHGNvW0u@orome.fritz.box/

Rob