linux-kernel - Re: [PATCH v3 1/2] dt-bindings: backlight: Add MPS MP3309C

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Message-ID: <20230926130113.GB4356@aspen.lan>
Date:   Tue, 26 Sep 2023 14:01:13 +0100
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, Rob Herring <robh@...nel.org>
Subject: Re: [PATCH v3 1/2] dt-bindings: backlight: Add MPS MP3309C

On Mon, Sep 25, 2023 at 02:26:08PM +0200, Flavio Suligoi wrote:
> The Monolithic Power (MPS) MP3309C is a WLED step-up converter, featuring a
> programmable switching frequency to optimize efficiency.
> The brightness can be controlled either by I2C commands (called "analog"
> mode) or by a PWM input signal (PWM mode).
> This driver supports both modes.
>
> For device driver details, please refer to:
> - drivers/video/backlight/mp3309c_bl.c
>
> The datasheet is available at:
> - https://www.monolithicpower.com/en/mp3309c.html
>
> Signed-off-by: Flavio Suligoi <f.suligoi@...m.it>
> Reviewed-by: Rob Herring <robh@...nel.org>
> ---
>
> v3:
>  - add default value for mps,overvoltage-protection-microvolt property
>  - fix the example, changing from "mps,mp3309c-backlight" to "mps,mp3309c" in
>    compatible property
> v2:
>  - remove useless properties (dimming-mode, pinctrl-names, pinctrl-0,
>    switch-on-delay-ms, switch-off-delay-ms, reset-gpios, reset-on-delay-ms,
>    reset-on-length-ms)
>  - add common.yaml#
>  - remove already included properties (default-brightness, max-brightness)
>  - substitute three boolean properties, used for the overvoltage-protection
>    values, with a single enum property
>  - remove some conditional definitions
>  - remove the 2nd example
> v1:
>  - first version
>
>  .../bindings/leds/backlight/mps,mp3309c.yaml  | 73 +++++++++++++++++++
>  1 file changed, 73 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/leds/backlight/mps,mp3309c.yaml
>
> diff --git a/Documentation/devicetree/bindings/leds/backlight/mps,mp3309c.yaml b/Documentation/devicetree/bindings/leds/backlight/mps,mp3309c.yaml
> new file mode 100644
> index 000000000000..4191e33626f5
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/leds/backlight/mps,mp3309c.yaml
> @@ -0,0 +1,73 @@
> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/leds/backlight/mps,mp3309c.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: MPS MP3309C backlight
> +
> +maintainers:
> +  - Flavio Suligoi <f.suligoi@...m.it>
> +
> +description: |
> +  The Monolithic Power (MPS) MP3309C is a WLED step-up converter, featuring a
> +  programmable switching frequency to optimize efficiency.
> +  It supports two different dimming modes:
> +
> +  - analog mode, via I2C commands (default)
> +  - PWM controlled mode.
> +
> +  The datasheet is available at:
> +  https://www.monolithicpower.com/en/mp3309c.html
> +
> +allOf:
> +  - $ref: common.yaml#
> +
> +properties:
> +  compatible:
> +    const: mps,mp3309c
> +
> +  reg:
> +    maxItems: 1
> +
> +  pwms:
> +    description: if present, the backlight is controlled in PWM mode.
> +    maxItems: 1
> +
> +  enable-gpios:
> +    description: GPIO used to enable the backlight in "analog-i2c" dimming mode.
> +    maxItems: 1
> +
> +  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
> +  - max-brightness

Why is this mandatory?

There's no point in setting max-brightness when running in I2C mode
(max-brightness should default to 31 in that case).


> +  - default-brightness

Again. I'm not clear why this needs to be mandatory.


Daniel.