linux-kernel - RE: [PATCH v4 1/2] dt-bindings: backlight: Add MPS MP3309C

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Message-ID: <AM8PR01MB8045F549C8A65A853E214D37F9CCA@AM8PR01MB8045.eurprd01.prod.exchangelabs.com>
Date:   Wed, 11 Oct 2023 15:13:20 +0000
From:   Flavio Suligoi <f.suligoi@...m.it>
To:     Rob Herring <robh@...nel.org>
CC:     Lee Jones <lee@...nel.org>,
        Daniel Thompson <daniel.thompson@...aro.org>,
        Jingoo Han <jingoohan1@...il.com>,
        Helge Deller <deller@....de>, Pavel Machek <pavel@....cz>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
        "linux-leds@...r.kernel.org" <linux-leds@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-fbdev@...r.kernel.org" <linux-fbdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH v4 1/2] dt-bindings: backlight: Add MPS MP3309C

Hi Rob,

just a question about led-backlight.yaml and pwm-backlight.yaml
common properties.

...

> > +
> > +  brightness-levels:
> > +    description:
> > +      Array of distinct brightness levels, in PWM dimming mode.
> > +      Typically these are in the range from 0 to 255, but any range starting
> > +      at 0 will do.
> > +      The 0 value 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
> 
> This already has a type defined. Please add it to backlight/common.yaml and
> remove from led-backlight.yaml and pwm-backlight.yaml.

As well as the brightness-levels property, also the default-brightness-level is in common
between led-backlight.yaml and pwm-backlight.yaml.
What do you think about removing it from both led-backlight.yaml and pwm-backlight.yaml, and
moving it into backlight/common.yaml?

> 
> You say 0-255 here, but your example is 0-10. One of those seems wrong.
> Anyways, don't define constraints in prose, use a schema:
> 
> items:
>   maximum: 10 (or 255?)
> 
> > +
> > +  default-brightness:
> > +    description:
> > +      The default brightness (index into the levels array).
> > +    $ref: /schemas/types.yaml#/definitions/uint32
> 
> Already has a type. You need to reference backlight/common.yaml.
> 
> > +
> > +  mps,overvoltage-protection-microvolt:
> > +    description: Overvoltage protection (13.5V, 24V or 35.5V).
> > +    enum: [ 13500000, 24000000, 35500000 ]
> > +    default: 35500000
> > +
> > +  mps,no-sync-mode:
> > +    description: disable synchronous rectification mode
> > +    type: boolean
> > +
> > +required:
> > +  - compatible
> > +  - reg
> > +
> > +unevaluatedProperties: false
> > +
> > +examples:
> > +  - |
> > +    i2c {
> > +        #address-cells = <1>;
> > +        #size-cells = <0>;
> > +
> > +        /* Backlight with PWM control */
> > +        backlight_pwm: backlight@17 {
> > +            compatible = "mps,mp3309c";
> > +            reg = <0x17>;
> > +            pwms = <&pwm1 0 3333333 0>; /* 300 Hz --> (1/f) * 1*10^9 */
> > +            brightness-levels = <0 1 2 3 4 5 6 7 8 9 10>;
> > +            default-brightness = <8>;
> > +            mps,overvoltage-protection-microvolt = <24000000>;
> > +        };
> > +    };
> > --
> > 2.34.1
> >

Regards,
Flavio