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From:   ChiaEn Wu <peterwu.pub@gmail.com>
Date:   Mon, 1 Aug 2022 14:47:36 +0800
Message-ID: <CABtFH5L83d5Di6O9TC-L3UX2ma5J3PE47ihfJFfPD5YGJ43NxQ@mail.gmail.com>
Subject: Re: [PATCH v6 05/13] dt-bindings: backlight: Add MediaTek MT6370 backlight
To:     Lee Jones <lee.jones@linaro.org>,
        Daniel Thompson <daniel.thompson@linaro.org>,
        Jingoo Han <jingoohan1@gmail.com>, Pavel Machek <pavel@ucw.cz>,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        Sebastian Reichel <sre@kernel.org>,
        Chunfeng Yun <chunfeng.yun@mediatek.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Jonathan Cameron <jic23@kernel.org>,
        Lars-Peter Clausen <lars@metafoo.de>,
        Liam Girdwood <lgirdwood@gmail.com>,
        Mark Brown <broonie@kernel.org>,
        Guenter Roeck <linux@roeck-us.net>,
        "Krogerus, Heikki" <heikki.krogerus@linux.intel.com>,
        Helge Deller <deller@gmx.de>,
        Andy Shevchenko <andy.shevchenko@gmail.com>
Cc:     ChiaEn Wu <chiaen_wu@richtek.com>,
        Alice Chen <alice_chen@richtek.com>,
        ChiYuan Huang <cy_huang@richtek.com>,
        dri-devel <dri-devel@lists.freedesktop.org>,
        Linux LED Subsystem <linux-leds@vger.kernel.org>,
        devicetree <devicetree@vger.kernel.org>,
        linux-arm Mailing List <linux-arm-kernel@lists.infradead.org>,
        "moderated list:ARM/Mediatek SoC support" 
        <linux-mediatek@lists.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Linux PM <linux-pm@vger.kernel.org>,
        USB <linux-usb@vger.kernel.org>,
        linux-iio <linux-iio@vger.kernel.org>,
        "open list:FRAMEBUFFER LAYER" <linux-fbdev@vger.kernel.org>,
        szuni chen <szunichen@gmail.com>, Rob Herring <robh@kernel.org>
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On Fri, Jul 22, 2022 at 6:24 PM ChiaEn Wu <peterwu.pub@gmail.com> wrote:
>
> Signed-off-by: ChiYuan Huang <cy_huang@richtek.com>
> Reviewed-by: Rob Herring <robh@kernel.org>
> ---

[snip]

> +  compatible:
> +    const: mediatek,mt6370-backlight
> +
> +  default-brightness:
> +    minimum: 0
> +    maximum: 2048
> +
> +  max-brightness:
> +    minimum: 0
> +    maximum: 2048
> +

Hi Rob, Krzysztof,

First, I'm so sorry for our SoB writing wrong, I'll fix it in the next patch.
Because of this mail thread
(https://lore.kernel.org/all/20220728113109.7gf3b36mqjxlhcq3@maple.lan/),
I would like to discuss with you that I may change the following in
this DT document, I am not sure whether you agree or not.

1. Add some descriptions about MT6372, which supports 16384 steps (14
bits) and is different from MT6370/MT6371 (2048 steps, 11 bits)
2. Modify the format of 'compatible' as follows to distinguish between
MT6370/MT6371 or MT6372
------------------------------------------
properties:
  compatible:
    enum:
      - mediatek,mt6370-backlight
      - mediatek,mt6372-backlight
------------------------------------------

3. Remove the 'maximum' value of 'default-brightness' and
'max-brightness', and add "if-else" to determine the "maximum" value
as follows
------------------------------------------
  default-brightness:
    minimum: 0

  max-brightness:
    minimum: 0

...

if:
  properties:
    compatible:
      contains:
        const: mediatek,mt6372-backlight

then:
  properties:
    default-brightness:
      maximum: 16384

    max-brightness:
      maximum: 16384

else:
  properties:
    default-brightness:
      maximum: 2048

    max-brightness:
      maximum: 2048
------------------------------------------

4. Add a new boolean property to allow the user to determine whether
to enable the exponential mode of backlight brightness or not. Like
this,
------------------------------------------
  mediatek,bled-exponential-mode-enable:
    description: |
      Enable the exponential mode of backlight brightness. If this property
      is not enabled, the default is to use linear mode.
    type: boolean
------------------------------------------

I hope these changes I have added will meet your expectations.
And I'm not sure if I should remove 'Reviewed-By' first until it
passes your review.
Thanks.

-- 
Best Regards,
ChiaEn Wu