linux-kernel - Re: [PATCH v7 1/2] dt-bindings: backlight: mp3309c: remove two required properties

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Date:   Thu, 16 Nov 2023 11:59:35 +0000
From:   Daniel Thompson <daniel.thompson@...aro.org>
To:     Flavio Suligoi <f.suligoi@...m.it>
Cc:     Lee Jones <lee@...nel.org>, Jingoo Han <jingoohan1@...il.com>,
        Helge Deller <deller@....de>, Pavel Machek <pavel@....cz>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        dri-devel@...ts.freedesktop.org, linux-leds@...r.kernel.org,
        devicetree@...r.kernel.org, linux-fbdev@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Conor Dooley <conor.dooley@...rochip.com>
Subject: Re: [PATCH v7 1/2] dt-bindings: backlight: mp3309c: remove two
 required properties

On Thu, Nov 16, 2023 at 11:53:18AM +0100, Flavio Suligoi wrote:
> The two properties:
>
> - max-brightness
> - default brightness
>
> 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:
>
> - for the "analog mode", via I2C commands, this value is fixed by
>   hardware (=31)
> - while in case of pwm mode the default used is the last value of the
>   brightness-levels array.
>
> Also the brightness-levels array is not required:
>
> - 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"
>
> 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 current
>       v6.7.0-rc1 kernel version.
>       No developer may have used it.
>
> Other changes:
>
> - improve the backlight working mode description, in the "description"
>   section
> - update the example, removing the "max-brightness" and introducing the
>   "brightess-levels" property
>
> Signed-off-by: Flavio Suligoi <f.suligoi@...m.it>
> Acked-by: Conor Dooley <conor.dooley@...rochip.com>

Reviewed-by: Daniel Thompson <daniel.thompson@...aro.org>


Daniel.