linux-kernel - Re: [PATCH v2 1/2] dt-bindings: input: Add Nuvoton MA35D1 keypad

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Message-ID: <20241112182551.GA1394330-robh@kernel.org>
Date: Tue, 12 Nov 2024 12:25:51 -0600
From: Rob Herring <robh@...nel.org>
To: mjchen <mjchen0829@...il.com>
Cc: dmitry.torokhov@...il.com, krzk+dt@...nel.org, conor+dt@...nel.org,
	sudeep.holla@....com, peng.fan@....com, arnd@...db.de,
	linux-arm-kernel@...ts.infradead.org, linux-input@...r.kernel.org,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
	mjchen@...oton.com
Subject: Re: [PATCH v2 1/2] dt-bindings: input: Add Nuvoton MA35D1 keypad

On Tue, Nov 12, 2024 at 05:30:58AM +0000, mjchen wrote:
> Add YAML bindings for MA35D1 SoC keypad.
> 
> Signed-off-by: mjchen <mjchen0829@...il.com>
> ---
>  .../bindings/input/nuvoton,ma35d1-keypad.yaml | 89 +++++++++++++++++++
>  1 file changed, 89 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/input/nuvoton,ma35d1-keypad.yaml
> 
> diff --git a/Documentation/devicetree/bindings/input/nuvoton,ma35d1-keypad.yaml b/Documentation/devicetree/bindings/input/nuvoton,ma35d1-keypad.yaml
> new file mode 100644
> index 000000000000..71debafc3890
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/input/nuvoton,ma35d1-keypad.yaml
> @@ -0,0 +1,89 @@
> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/input/nuvoton,ma35d1-keypad.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Nuvoton MA35D1 Keypad
> +
> +maintainers:
> +  - Ming-jen Chen <mjchen0829@...il.com>
> +
> +allOf:
> +  - $ref: /schemas/input/matrix-keymap.yaml#
> +
> +properties:
> +  compatible:
> +    const: nuvoton,ma35d1-kpi
> +
> +  debounce-period:
> +    $ref: /schemas/types.yaml#/definitions/uint32
> +    enum: [0, 8, 16, 32, 64, 128, 256, 512, 1024, 2048, 4096, 8192]
> +    description: |
> +      Key debounce period select, specified in terms of keypad IP clock cycles.
> +      Valid values include 0 (no debounce) and specific clock cycle values:
> +      8, 16, 32, 64, 128, 256, 512, 1024, 2048, 4096, and 8192.

No need to list the values twice.

We already have a bunch of debounce time properties. Don't add more. If 
you have the clock frequency, then you can use the existing 
"debounce-delay-ms" and convert to register values.

> +
> +  nuvoton,key-scan-time:
> +    $ref: /schemas/types.yaml#/definitions/uint32
> +    description: |
> +      Set the time it takes to scan each key in the keypad, in clock cycles of the IP.
> +      This parameter controls how frequently the keypad is scanned, adjusting the response time.
> +      The valid range is from 1 to 256 clock cycles.
> +    minimum: 1
> +    maximum: 256
> +
> +  nuvoton,key-scan-time-div:
> +    $ref: /schemas/types.yaml#/definitions/uint32
> +    description: |
> +      Set a divider that adjusts the scan time for each key.
> +      This value scales the time it takes to scan each key
> +      by multiplying the key-scan-time by the specified factor.
> +      For example, if you set key-scan-time to 64 cycles and configure key-scan-time-div to 2,
> +      the scan time for each key will be increased to 128 cycles (64 cycles * 2). time.
> +    minimum: 1
> +    maximum: 256

Again, we have existing properties such as scan-interval, 
scan-interval-ms, and scan-delay. How is this different? 

With a single property in time units, you can solve for how many clock 
cycles.


> +
> +  reg:
> +    maxItems: 1
> +
> +  interrupts:
> +    maxItems: 1
> +
> +  clocks:
> +    maxItems: 1
> +
> +required:
> +  - compatible
> +  - reg
> +  - interrupts
> +  - clocks
> +  - linux,keymap
> +  - debounce-period
> +  - nuvoton,key-scan-time
> +  - nuvoton,key-scan-time-div
> +
> +unevaluatedProperties: false
> +
> +examples:
> +  - |
> +    #include <dt-bindings/input/input.h>
> +    keypad@...A0000 {
> +      compatible = "nuvoton,ma35d1-kpi";
> +      reg = <0x404A0000 0x10000>;
> +      interrupts = <79>;
> +      clocks = <&clk>;

> +      keypad,num-rows = <2>;
> +      keypad,num-columns = <2>;

Surely these should be required?

> +
> +      linux,keymap = <
> +         MATRIX_KEY(0, 0, KEY_ENTER)
> +         MATRIX_KEY(0, 1, KEY_ENTER)
> +         MATRIX_KEY(1, 0, KEY_SPACE)
> +         MATRIX_KEY(1, 1, KEY_Z)
> +      >;
> +
> +      debounce-period = <8>;
> +      nuvoton,key-scan-time = <1>;
> +      nuvoton,key-scan-time-div = <24>;
> +    };
> -- 
> 2.25.1
>