Re: [PATCH 1/3 v2] dt-bindings: backlight: Add some common backlight properties

[Rob Herring <robh@kernel.org>]

On Wed, Aug 12, 2020 at 2:58 AM Linus Walleij <linus.walleij@linaro.org> wrote:
>
> Let's use a common.yaml include for the backlight like we do with
> the LEDs. The LEDs are inherently incompatible so their bindings
> cannot be reused for backlight.
>
> Cc: devicetree@vger.kernel.org
> Suggested-by: Sam Ravnborg <sam@ravnborg.org>
> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
> ---
> ChangeLog v1->v2:
> - New patch as suggested by Sam.
> ---
>  .../bindings/leds/backlight/common.yaml       | 42 +++++++++++++++++++
>  1 file changed, 42 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/leds/backlight/common.yaml

I'd expect some refactoring here with existing backlight schemas
including the ones I just added for 5.9.

Ideally, we shouldn't have any property have a type definition more
than once. (We don't have any way to detect that though it wouldn't be
hard to write a program to do so).

> diff --git a/Documentation/devicetree/bindings/leds/backlight/common.yaml b/Documentation/devicetree/bindings/leds/backlight/common.yaml
> new file mode 100644
> index 000000000000..8ae7e3818b0d
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/leds/backlight/common.yaml
> @@ -0,0 +1,42 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/leds/backlight/common.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Common backlight properties
> +
> +maintainers:
> +  - Lee Jones <lee.jones@linaro.org>
> +  - Daniel Thompson <daniel.thompson@linaro.org>
> +  - Jingoo Han <jingoohan1@gmail.com>
> +
> +description: |

You don't need '|' if there's no formatting to preserve.

> +  Backlight devices provide backlight for different types of graphical
> +  displays. They are typically but not necessarilt implemented using a white

typo

> +  LED powered by a boost converter.
> +
> +properties:
> +  default-on:
> +    description:
> +      The initial state of the backlight can be set to be on with this
> +      property. This is a state applied by the operating system so that the
> +      backlight is always turned on at boot.

Needs a type.

> +
> +  default-brightness:
> +    description:
> +      The default brightness that should be applied to the LED by the operating
> +      system on start-up. The brightness should not exceed the brightness the
> +      LED can provide.
> +    $ref: /schemas/types.yaml#definitions/uint32
> +    minimum: 0

It's an unsigned int, so the min is already 0.

> +
> +  max-brightness:
> +    description:
> +      Normally the maximum brightness is determined by the hardware and this
> +      property is not required. This property is used to put a software limit
> +      on the brightness apart from what the driver says, as it could happen
> +      that a LED can be made so bright that it gets damaged or causes damage
> +      due to restrictions in a specific system, such as mounting conditions.
> +    $ref: /schemas/types.yaml#definitions/uint32
> +    minimum: 0