Re: [PATCH 1/2 v1] dt-bindings: backlight: Add Kinetic KTD253 bindings

[Sam Ravnborg <sam@ravnborg.org>]

Hi Linus.

On Mon, Jul 20, 2020 at 10:35:05PM +0200, Linus Walleij wrote:
> This adds device tree bindings for the Kinetic KTD253
> white LED backlight driver.
> 
> Cc: devicetree@vger.kernel.org
> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

See a few comments in the following.

	Sam

> ---
>  .../leds/backlight/kinetic,ktd253.yaml        | 48 +++++++++++++++++++
>  1 file changed, 48 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/leds/backlight/kinetic,ktd253.yaml
> 
> diff --git a/Documentation/devicetree/bindings/leds/backlight/kinetic,ktd253.yaml b/Documentation/devicetree/bindings/leds/backlight/kinetic,ktd253.yaml
> new file mode 100644
> index 000000000000..610bf9a0e270
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/leds/backlight/kinetic,ktd253.yaml
> @@ -0,0 +1,48 @@
> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/leds/backlight/kinetic,ktd253.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Kinetic Technologies KTD253 one-wire backlight
> +
> +maintainers:
> +  - Linus Walleij <linus.walleij@linaro.org>
> +
> +description: |
> +  The Kinetic Technologies KTD253 is a white LED backlight that is
> +  controlled by a single GPIO line. If you just turn on the backlight
> +  it goes to maximum backlight then you can set the level of backlight
> +  using pulses on the enable wire.

No $ref for common.yaml?

> +
> +properties:
> +  compatible:
> +    const: kinetic,ktd253
> +
> +  gpios:
A less generic and more descriptive name would be good.

> +    description: GPIO to use to enable/disable and dim the backlight.
> +    maxItems: 1
> +
> +  default-brightness:
> +    description: Default brightness level on boot. 0 is off.
> +    minimum: 0
> +    maximum: 255
> +
> +  max-brightness:
> +    description: Maximum brightness that is allowed during runtime.
> +    minimum: 0
> +    maximum: 255
Both looks like candidates for common.yaml - they are used by other
bindings.

> +
> +required:
> +  - compatible
> +  - gpios
It would make senste that maximum-brighness was mandatory too.

addtionalProperties: false??

> +
> +examples:
> +  - |
> +    #include <dt-bindings/gpio/gpio.h>
> +    backlight {
> +        compatible = "kinetic,ktd253";
> +        gpios = <&gpio2 5 GPIO_ACTIVE_HIGH>;
> +        default-on;
default-on is not documented - and not part of common.yaml.

> +        default-brightness = <160>;
> +    };
> -- 
> 2.26.2
> 
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