linux-kernel - Re: [PATCH v2 05/15] dt-bindings: backlight: Add Mediatek MT6370 backlight

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Message-ID: <9c38f708-1376-aa89-2c56-c08d320bcf2b@linaro.org>
Date:   Thu, 16 Jun 2022 14:13:37 -0700
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     ChiaEn Wu <peterwu.pub@...il.com>, jic23@...nel.org,
        lars@...afoo.de, matthias.bgg@...il.com, lee.jones@...aro.org,
        daniel.thompson@...aro.org, jingoohan1@...il.com, pavel@....cz,
        robh+dt@...nel.org, krzysztof.kozlowski+dt@...aro.org
Cc:     linux-iio@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, linux-kernel@...r.kernel.org,
        dri-devel@...ts.freedesktop.org, linux-leds@...r.kernel.org,
        devicetree@...r.kernel.org, linux-pm@...r.kernel.org,
        linux-usb@...r.kernel.org, linux-fbdev@...r.kernel.org,
        szunichen@...il.com, ChiYuan Huang <cy_huang@...htek.com>
Subject: Re: [PATCH v2 05/15] dt-bindings: backlight: Add Mediatek MT6370
 backlight

On 13/06/2022 04:11, ChiaEn Wu wrote:
> From: ChiYuan Huang <cy_huang@...htek.com>
> 
> Add mt6370 backlight binding documentation.
> 
> Signed-off-by: ChiYuan Huang <cy_huang@...htek.com>
> ---
>  .../backlight/mediatek,mt6370-backlight.yaml  | 107 ++++++++++++++++++
>  1 file changed, 107 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/leds/backlight/mediatek,mt6370-backlight.yaml
> 
> diff --git a/Documentation/devicetree/bindings/leds/backlight/mediatek,mt6370-backlight.yaml b/Documentation/devicetree/bindings/leds/backlight/mediatek,mt6370-backlight.yaml
> new file mode 100644
> index 000000000000..25a05e607e83
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/leds/backlight/mediatek,mt6370-backlight.yaml
> @@ -0,0 +1,107 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/leds/backlight/mediatek,mt6370-backlight.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Mediatek MT6370 Backlight
> +
> +maintainers:
> +  - ChiaEn Wu <chiaen_wu@...htek.com>
> +
> +description: |
> +  This module is part of the MT6370 MFD device.
> +  The MT6370 Backlight WLED driver supports up to a 29V output voltage for
> +  4 channels of 8 series WLEDs. Each channel supports up to 30mA of current
> +  capability with 2048 current steps (11 bits) in exponential or linear
> +  mapping curves.
> +
> +allOf:
> +  - $ref: common.yaml#
> +
> +properties:
> +  compatible:
> +    const: mediatek,mt6370-backlight
> +
> +  default-brightness:
> +    minimum: 0
> +    maximum: 2048
> +
> +  max-brightness:
> +    minimum: 0
> +    maximum: 2048
> +
> +  enable-gpios:
> +    description: External backlight 'enable' pin
> +    maxItems: 1
> +
> +  mediatek,bled-pwm-enable:
> +    description: |
> +      Enable external PWM input for backlight dimming
> +    type: boolean
> +
> +  mediatek,bled-pwm-hys-enable:
> +    description: |
> +      Enable the backlight input-hysteresis for PWM mode
> +    type: boolean
> +
> +  mediatek,bled-pwm-hys-input-bit:
> +    $ref: /schemas/types.yaml#/definitions/uint8
> +    enum: [0, 1, 2, 3]
> +    description: |
> +      The selection of the upper and lower bounds threshold of backlight
> +      PWM resolution. If we choose selection 3 (6 bits), the variation of PWM
> +      resolution needs over than 64 steps (2^6).
> +      value mapping:
> +        - 0: 1
> +        - 1: 2
> +        - 2: 4
> +        - 3: 6

Nope, I said last time:
"In any case you cannot have values mapping"

Please use proper real world value, not some register bits. The property
name also needs fixing.

> +
> +  mediatek,bled-ovp-shutdown:
> +    description: |
> +      Enable the backlight shutdown when OVP level triggered
> +    type: boolean
> +
> +  mediatek,bled-ovp-microvolt:
> +    enum: [0, 1, 2, 3]
> +    description: |
> +      Backlight OVP level selection.
> +      value mapping:
> +        - 0: 17000000
> +        - 1: 21000000
> +        - 2: 25000000
> +        - 3: 29000000

No. Please test your bindings.

microvolt cannot be 1 mV. It's 21000000, not 1. No value mappings.

> +
> +  mediatek,bled-ocp-shutdown:
> +    description: |
> +      Enable the backlight shutdown when OCP level triggerred.
> +    type: boolean
> +
> +  mediatek,bled-ocp-microamp:
> +    enum: [0, 1, 2, 3]
> +    description: |
> +      Backlight OC level selection.
> +      value mapping:
> +        - 0: 900000
> +        - 1: 1200000
> +        - 2: 1500000
> +        - 3: 1800000

Nope.

> +
> +  mediatek,bled-channel-use:
> +    $ref: /schemas/types.yaml#/definitions/uint8
> +    description: |
> +      Backlight LED channel to be used.
> +      Each bit mapping to:
> +        - 0: CH4
> +        - 1: CH3
> +        - 2: CH2
> +        - 3: CH1
> +    minimum: 1
> +    maximum: 15
> +
> +required:
> +  - compatible
> +  - mediatek,bled-channel-use
> +
> +additionalProperties: false


Best regards,
Krzysztof