Re: [PATCH] dt-bindings: backlight: Convert common backlight bindings to DT schema

On Thu, Jun 18, 2020 at 04:44:13PM -0600, Rob Herring wrote:

Convert the common GPIO, LED, and PWM backlight bindings to DT schema format.

Given there's only 2 common properties and the descriptions are slightly different, I opted to not create a common backlight schema.

Cc: Lee Jones lee.jones@linaro.org Cc: Daniel Thompson daniel.thompson@linaro.org Cc: Jingoo Han jingoohan1@gmail.com Signed-off-by: Rob Herring robh@kernel.org

...

diff --git a/Documentation/devicetree/bindings/leds/backlight/led-backlight.yaml b/Documentation/devicetree/bindings/leds/backlight/led-backlight.yaml new file mode 100644 index 000000000000..ae50945d2798 --- /dev/null +++ b/Documentation/devicetree/bindings/leds/backlight/led-backlight.yaml @@ -0,0 +1,58 @@ +# SPDX-License-Identifier: GPL-2.0-only +%YAML 1.2 +--- +$id: http://devicetree.org/schemas/leds/backlight/led-backlight.yaml# +$schema: http://devicetree.org/meta-schemas/core.yaml#

+title: led-backlight bindings

+maintainers:

• • Lee Jones lee.jones@linaro.org
• • Daniel Thompson daniel.thompson@linaro.org
• • Jingoo Han jingoohan1@gmail.com

+description:

• This binding is used to describe a basic backlight device made of LEDs. It
• can also be used to describe a backlight device controlled by the output of
• a LED driver.

+properties:

• compatible:
• const: led-backlight
• leds:
• description: A list of LED nodes
• $ref: /schemas/types.yaml#/definitions/phandle-array
• brightness-levels:
• description: Array of distinct brightness levels. The levels must be

•  in the range accepted by the underlying LED devices. This is used
  

•  to translate a backlight brightness level into a LED brightness level.
  

•  If it is not provided, the identity mapping is used.
  

• $ref: /schemas/types.yaml#/definitions/uint32-array
• default-brightness-level:
• description: The default brightness level (index into the array defined

•  by the "brightness-levels" property).
  

• $ref: /schemas/types.yaml#/definitions/uint32

+dependencies:

• default-brightness-level: [brightness-levels]

I don't think there is a dependency here. default-brightness-level still makes sense with there is no mapping table present.

Based on Sam's feedback perhaps adding ("if one is provided") to the parenthetic text.

diff --git a/Documentation/devicetree/bindings/leds/backlight/pwm-backlight.yaml b/Documentation/devicetree/bindings/leds/backlight/pwm-backlight.yaml new file mode 100644 index 000000000000..7e1f109a38a4 --- /dev/null +++ b/Documentation/devicetree/bindings/leds/backlight/pwm-backlight.yaml @@ -0,0 +1,98 @@ +# SPDX-License-Identifier: GPL-2.0-only +%YAML 1.2 +--- +$id: http://devicetree.org/schemas/leds/backlight/pwm-backlight.yaml# +$schema: http://devicetree.org/meta-schemas/core.yaml#

+title: pwm-backlight bindings

+maintainers:

• • Lee Jones lee.jones@linaro.org
• • Daniel Thompson daniel.thompson@linaro.org
• • Jingoo Han jingoohan1@gmail.com

+properties:

• compatible:
• const: pwm-backlight
• pwms:
• maxItems: 1
• pwm-names: true
• power-supply:
• description: regulator for supply voltage
• enable-gpios:
• description: Contains a single GPIO specifier for the GPIO which enables

•  and disables the backlight
  

• maxItems: 1
• post-pwm-on-delay-ms:
• description: Delay in ms between setting an initial (non-zero) PWM and

•  enabling the backlight using GPIO.
  

• pwm-off-delay-ms:
• description: Delay in ms between disabling the backlight using GPIO

•  and setting PWM value to 0.
  

• brightness-levels:
• description: Array of distinct brightness levels. Typically these are

•  in the range from 0 to 255, but any range starting at 0 will do. The
  

•  actual brightness level (PWM duty cycle) will be interpolated from
  

•  these values. 0 means a 0% duty cycle (darkest/off), while the last
  

•  value in the array represents a 100% duty cycle (brightest).
  

• $ref: /schemas/types.yaml#/definitions/uint32-array
• default-brightness-level:
• description: The default brightness level (index into the array defined

•  by the "brightness-levels" property).
  

• $ref: /schemas/types.yaml#/definitions/uint32
• num-interpolated-steps:
• description: Number of interpolated steps between each value of brightness-levels

•  table. This way a high resolution pwm duty cycle can be used without
  

•  having to list out every possible value in the brightness-level array.
  

• $ref: /schemas/types.yaml#/definitions/uint32

+dependencies:

• default-brightness-level: [brightness-levels]
• num-interpolated-steps: [brightness-levels]

Just for the record, these dependencies are OK. Iit isn't really a good idea to map 1:1 to a PWM since we end up with a gazillion indistinguishable levels so the bindings (and the driver) to not allow such a mode.

Daniel.