linux-kernel - Re: [PATCH 1/2] dt-bindings: input: microchip,cap11xx: add advanced sensitivity settings

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Message-ID: <8a790966-d985-c0fc-498e-c17e69a6622e@linaro.org>
Date:   Sat, 15 Apr 2023 11:10:59 +0200
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     Jiri Valek - 2N <jiriv@...s.com>, dmitry.torokhov@...il.com,
        krzysztof.kozlowski+dt@...aro.org
Cc:     devicetree@...r.kernel.org, linux-input@...r.kernel.org,
        linux-kernel@...r.kernel.org, robh+dt@...nel.org,
        u.kleine-koenig@...gutronix.de
Subject: Re: [PATCH 1/2] dt-bindings: input: microchip,cap11xx: add advanced
 sensitivity settings

On 15/04/2023 01:38, Jiri Valek - 2N wrote:
> Add support for advanced sensitivity settings and signal guard feature.
> 
> Signed-off-by: Jiri Valek - 2N <jiriv@...s.com>
> ---
>  .../bindings/input/microchip,cap11xx.yaml     | 64 ++++++++++++++++++-
>  1 file changed, 61 insertions(+), 3 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/input/microchip,cap11xx.yaml b/Documentation/devicetree/bindings/input/microchip,cap11xx.yaml
> index 5fa625b5c5fb..08e28226a164 100644
> --- a/Documentation/devicetree/bindings/input/microchip,cap11xx.yaml
> +++ b/Documentation/devicetree/bindings/input/microchip,cap11xx.yaml
> @@ -45,13 +45,13 @@ properties:
>        Enables the Linux input system's autorepeat feature on the input device.
>  
>    linux,keycodes:
> -    minItems: 6
> -    maxItems: 6
> +    minItems: 3
> +    maxItems: 8
>      description: |
>        Specifies an array of numeric keycode values to
>        be used for the channels. If this property is
>        omitted, KEY_A, KEY_B, etc are used as defaults.
> -      The array must have exactly six entries.
> +      The number of entries must correspond to the number of channels.
>  
>    microchip,sensor-gain:
>      $ref: /schemas/types.yaml#/definitions/uint32
> @@ -70,6 +70,58 @@ properties:
>        open drain. This property allows using the active
>        high push-pull output.
>  
> +  microchip,sensitivity-delta-sense:
> +    $ref: /schemas/types.yaml#/definitions/uint32
> +    default: 32
> +    enum: [1, 2, 4, 8, 16, 32, 64, 128]
> +    description: |

Do not need '|' unless you need to preserve formatting.

> +      Optional parameter. Controls the sensitivity multiplier of a touch detection.
> +      At the more sensitive settings, touches are detected for a smaller delta
> +      capacitance corresponding to a “lighter” touch.
> +
> +  microchip,sensitivity-base-shift:
> +    $ref: /schemas/types.yaml#/definitions/uint32
> +    default: 256
> +    enum: [1, 2, 4, 8, 16, 32, 64, 128, 256]
> +    description: |
> +      Optional parameter. Controls data scaling factor.
> +      The higher the value of these bits, the larger the range and the lower
> +      the resolution of the data presented. These settings will not affect
> +      touch detection or sensitivity.
> +
> +  microchip,signal-guard:
> +    minItems: 3
> +    maxItems: 8
> +    enum: [0, 1]
> +    default: 0

This was not really tested. Missing ref, mixing scalar and array
properties. You want items with enum. And drop default.


> +    description: |
> +      Optional parameter supported only for CAP129x.

Then disallow it for others (allOf:if:then: ...
microchip,signal-guard:false)
> +      The signal guard isolates the signal from virtual grounds.
> +      If enabled then the behavior of the channel is changed to signal guard.
> +      The number of entries must correspond to the number of channels.
> +
> +  microchip,input-treshold:
> +    minItems: 3
> +    maxItems: 8
> +    minimum: 0
> +    maximum: 127
> +    default: 64
> +    description: |
> +      Optional parameter. Specifies the delta threshold that is used to
> +      determine if a touch has been detected.
> +      The number of entries must correspond to the number of channels.
> +
> +  microchip,calib-sensitivity:
> +    minItems: 3
> +    maxItems: 8
> +    enum: [1, 2, 4]
> +    default: 1
> +    description: |
> +      Optional parameter supported only for CAP129x. Specifies an array of
> +      numeric values that controls the gain used by the calibration routine to
> +      enable sensor inputs to be more sensitive for proximity detection.
> +      The number of entries must correspond to the number of channels.

Most of these properties do not look like hardware properties. Policies
and runtime configuration should not be put into DT. Explain please why
these are board-specific thus suitable for DT.


Best regards,
Krzysztof