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Date:   Thu, 26 Oct 2023 15:57:40 +0100
From:   Conor Dooley <conor@kernel.org>
To:     Flavio Suligoi <f.suligoi@asem.it>
Cc:     Lee Jones <lee@kernel.org>,
        Daniel Thompson <daniel.thompson@linaro.org>,
        Jingoo Han <jingoohan1@gmail.com>,
        Helge Deller <deller@gmx.de>, Pavel Machek <pavel@ucw.cz>,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Conor Dooley <conor+dt@kernel.org>,
        dri-devel@lists.freedesktop.org, linux-leds@vger.kernel.org,
        devicetree@vger.kernel.org, linux-fbdev@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 1/1] dt-bindings: backlight: mp3309c: remove two
 required properties
Message-ID: <20231026-ride-sushi-bc53cbb4b7f3@spud>
References: <20231025155057.886823-1-f.suligoi@asem.it>
 <20231025155057.886823-2-f.suligoi@asem.it>
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On Wed, Oct 25, 2023 at 05:50:57PM +0200, Flavio Suligoi wrote:
> The two properties:
>=20
> - max-brightness
> - default brightness
>=20
> are not really required, so they can be removed from the "required"
> section.
> The "max-brightness" is no longer used in the current version
> of the driver (it was used only in the first version).
> The "default-brightness", if omitted in the DT, is managed by the
> device driver, using a default value. This value depends on the dimming
> mode used:
>=20
> - for the "analog mode", via I2C commands, this value is fixed by
>   hardware (=3D31)
> - while in case of pwm mode the default used is the last value of the
>   brightness-levels array.
>=20
> Also the brightness-levels array is not required:
>=20
> - in "analog mode", via I2C commands, the brightness-level array is
>   fixed by hardware (0..31).;
> - in pwm dimming mode, the driver uses a default array of 0..255 and
>   the "default-brightness" is the last one, which is "255"
>=20

> NOTE: there are no compatibility problems with the previous version,
>       since the device driver has not yet been included in any kernel.
>       Only this dt-binding yaml file is already included in the
>       "for-backlight-next" branch of the "backlight" kernel repository.
>       No developer may have used it.

I'd argue
Fixes: 02c4e661658f ("dt-bindings: backlight: Add MPS MP3309C")
but that's up to Lee.
Acked-by: Conor Dooley <conor.dooley@microchip.com>

Thanks,
Conor.

>=20
> Other changes:
>=20
> - improve the backlight working mode description, in the "description"
>   section
> - update the example, removing the "max-brightness" and introducing the
>   "brightess-levels" property
>=20
> Signed-off-by: Flavio Suligoi <f.suligoi@asem.it>
> ---
>  .../bindings/leds/backlight/mps,mp3309c.yaml           | 10 ++++------
>  1 file changed, 4 insertions(+), 6 deletions(-)
>=20
> diff --git a/Documentation/devicetree/bindings/leds/backlight/mps,mp3309c=
=2Eyaml b/Documentation/devicetree/bindings/leds/backlight/mps,mp3309c.yaml
> index 4191e33626f5..527a37368ed7 100644
> --- a/Documentation/devicetree/bindings/leds/backlight/mps,mp3309c.yaml
> +++ b/Documentation/devicetree/bindings/leds/backlight/mps,mp3309c.yaml
> @@ -14,8 +14,8 @@ description: |
>    programmable switching frequency to optimize efficiency.
>    It supports two different dimming modes:
> =20
> -  - analog mode, via I2C commands (default)
> -  - PWM controlled mode.
> +  - analog mode, via I2C commands, as default mode (32 dimming levels)
> +  - PWM controlled mode (optional)
> =20
>    The datasheet is available at:
>    https://www.monolithicpower.com/en/mp3309c.html
> @@ -50,8 +50,6 @@ properties:
>  required:
>    - compatible
>    - reg
> -  - max-brightness
> -  - default-brightness
> =20
>  unevaluatedProperties: false
> =20
> @@ -66,8 +64,8 @@ examples:
>              compatible =3D "mps,mp3309c";
>              reg =3D <0x17>;
>              pwms =3D <&pwm1 0 3333333 0>; /* 300 Hz --> (1/f) * 1*10^9 */
> -            max-brightness =3D <100>;
> -            default-brightness =3D <80>;
> +            brightness-levels =3D <0 4 8 16 32 64 128 255>;
> +            default-brightness =3D <6>;
>              mps,overvoltage-protection-microvolt =3D <24000000>;
>          };
>      };
> --=20
> 2.34.1
>=20

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