Hi, On Thu, Apr 29, 2021 at 11:04 AM Rob Herring <robh@xxxxxxxxxx> wrote: > > 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@xxxxxxxxxxxxxx> > > --- > > .../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@xxxxxxxxxxxxxx> > > + > > +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@xxxxxxxxxxxxxxx/ I think Rajeev needs to rework everything anyway as per: https://lore.kernel.org/r/87zgxl5qar.fsf@xxxxxxxxx ...but you're right that it makes sense not to model the backlight as a separate node in the device tree. The panel driver can handle setting up the backlight. -Doug
