linux-kernel - Re: [PATCH v2 1/2] dt-bindings: backlight: document new property default-brightness-level

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Message-ID: <20230622021303.GA68330-robh@kernel.org>
Date:   Wed, 21 Jun 2023 20:13:03 -0600
From:   Rob Herring <robh@...nel.org>
To:     Alexandru Ardelean <alex@...uggie.ro>
Cc:     dri-devel@...ts.freedesktop.org, linux-leds@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-fbdev@...r.kernel.org, lee@...nel.org,
        daniel.thompson@...aro.org, jingoohan1@...il.com, pavel@....cz,
        krzysztof.kozlowski+dt@...aro.org, conor+dt@...nel.org,
        deller@....de, Yannick Fertre <yannick.fertre@...s.st.com>
Subject: Re: [PATCH v2 1/2] dt-bindings: backlight: document new property
 default-brightness-level

On Thu, Jun 22, 2023 at 12:54:56AM +0300, Alexandru Ardelean wrote:
> From: Yannick Fertre <yannick.fertre@...s.st.com>
> 
> Add documentation for new default-brightness-level property.

Why?

> 
> Signed-off-by: Yannick Fertre <yannick.fertre@...s.st.com>
> Signed-off-by: Alexandru Ardelean <alex@...uggie.ro>
> ---
> 
> Link to original patch:
>   https://github.com/STMicroelectronics/linux/commit/c4067d7bd883c6fa14ffd49892c4ce663cdafe98
> 
> Changelog v1 -> v2:
> * https://lore.kernel.org/dri-devel/20230519200520.10657-2-alex@shruggie.ro/
> * removed 'brightness-levels' reference
> * updated doc-text for 'default-brightness-level'
> * updated doc-text for 'default-on'
> * added 'minimum' & 'maximum' to 'default-brightness-level' property
> * removed 'Reviewed-by: Philippe CORNU <philippe.cornu@...s.st.com>' as
>   requested
> * patch is first in series of 2 patches (was second patch)
> 
>  .../bindings/leds/backlight/gpio-backlight.yaml    | 14 +++++++++++++-
>  1 file changed, 13 insertions(+), 1 deletion(-)
> 
> diff --git a/Documentation/devicetree/bindings/leds/backlight/gpio-backlight.yaml b/Documentation/devicetree/bindings/leds/backlight/gpio-backlight.yaml
> index 584030b6b0b9..2da6552a207c 100644
> --- a/Documentation/devicetree/bindings/leds/backlight/gpio-backlight.yaml
> +++ b/Documentation/devicetree/bindings/leds/backlight/gpio-backlight.yaml
> @@ -20,9 +20,21 @@ properties:
>      maxItems: 1
>  
>    default-on:
> -    description: enable the backlight at boot.
> +    description:
> +      The default power state of the backlight at boot.
>      type: boolean
>  
> +  default-brightness-level:
> +    description:
> +      The default brightness level on device init. The value can be 0 or 1.
> +      If omitted, the value is 1. In the context of the "gpio-backlight" driver
> +      the effect of this setting will be that the backlight is on/off.
> +      The difference between this setting and "default-on" is that this handles
> +      brightness, while "default-on" handles the power setting of the device.

What power setting? You only have 1 GPIO to control here which is 2 
states. I fail to see why you need 6 possible states with all the 
combinations of 2 properties.

> +    $ref: /schemas/types.yaml#/definitions/uint32
> +    minimum: 0
> +    maximum: 1
> +
>  required:
>    - compatible
>    - gpios
> -- 
> 2.40.1
>