Re: [PATCH v3 09/11] dt-bindings: input: Document hid-over-spi DT schema

[Conor Dooley <conor@kernel.org>]

[-- Attachment #1: Type: text/plain, Size: 5441 bytes --]

On Thu, Apr 02, 2026 at 01:59:46AM +0000, Jingyuan Liang wrote:
> Documentation describes the required and optional properties for
> implementing Device Tree for a Microsoft G6 Touch Digitizer that
> supports HID over SPI Protocol 1.0 specification.
> 
> The properties are common to HID over SPI.
> 
> Signed-off-by: Dmitry Antipov <dmanti@microsoft.com>
> Signed-off-by: Jarrett Schultz <jaschultz@microsoft.com>
> Signed-off-by: Jingyuan Liang <jingyliang@chromium.org>
> ---
>  .../devicetree/bindings/input/hid-over-spi.yaml    | 126 +++++++++++++++++++++
>  1 file changed, 126 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/input/hid-over-spi.yaml b/Documentation/devicetree/bindings/input/hid-over-spi.yaml
> new file mode 100644
> index 000000000000..d1b0a2e26c32
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/input/hid-over-spi.yaml
> @@ -0,0 +1,126 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/input/hid-over-spi.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: HID over SPI Devices
> +
> +maintainers:
> +  - Benjamin Tissoires <benjamin.tissoires@redhat.com>
> +  - Jiri Kosina <jkosina@suse.cz>

Why them and not you, the developers of the series?

> +
> +description: |+
> +  HID over SPI provides support for various Human Interface Devices over the
> +  SPI bus. These devices can be for example touchpads, keyboards, touch screens
> +  or sensors.
> +
> +  The specification has been written by Microsoft and is currently available
> +  here: https://www.microsoft.com/en-us/download/details.aspx?id=103325
> +
> +  If this binding is used, the kernel module spi-hid will handle the
> +  communication with the device and the generic hid core layer will handle the
> +  protocol.

This is not relevant to the binding, please remove it.

> +
> +allOf:
> +  - $ref: /schemas/input/touchscreen/touchscreen.yaml#
> +
> +properties:
> +  compatible:
> +    oneOf:
> +      - items:
> +          - enum:
> +              - microsoft,g6-touch-digitizer
> +          - const: hid-over-spi
> +      - description: Just "hid-over-spi" alone is allowed, but not recommended.
> +        const: hid-over-spi

Why is it allowed but not recommended? Seems to me like we should
require device-specific compatibles.

> +
> +  reg:
> +    maxItems: 1
> +
> +  interrupts:
> +    maxItems: 1
> +
> +  reset-gpios:
> +    maxItems: 1
> +    description:
> +      GPIO specifier for the digitizer's reset pin (active low). The line must
> +      be flagged with GPIO_ACTIVE_LOW.
> +
> +  vdd-supply:
> +    description:
> +      Regulator for the VDD supply voltage.
> +
> +  input-report-header-address:
> +    $ref: /schemas/types.yaml#/definitions/uint32
> +    minimum: 0
> +    maximum: 0xffffff
> +    description:
> +      A value to be included in the Read Approval packet, listing an address of
> +      the input report header to be put on the SPI bus. This address has 24
> +      bits.
> +
> +  input-report-body-address:
> +    $ref: /schemas/types.yaml#/definitions/uint32
> +    minimum: 0
> +    maximum: 0xffffff
> +    description:
> +      A value to be included in the Read Approval packet, listing an address of
> +      the input report body to be put on the SPI bus. This address has 24 bits.
> +
> +  output-report-address:
> +    $ref: /schemas/types.yaml#/definitions/uint32
> +    minimum: 0
> +    maximum: 0xffffff
> +    description:
> +      A value to be included in the Output Report sent by the host, listing an
> +      address where the output report on the SPI bus is to be written to. This
> +      address has 24 bits.
> +
> +  read-opcode:
> +    $ref: /schemas/types.yaml#/definitions/uint8
> +    description:
> +      Value to be used in Read Approval packets. 1 byte.
> +
> +  write-opcode:
> +    $ref: /schemas/types.yaml#/definitions/uint8
> +    description:
> +      Value to be used in Write Approval packets. 1 byte.

Why can none of these things be determined from the device's compatible?
On the surface, they like the kinds of things that could/should be.

Cheers,
Conor.

> +
> +required:
> +  - compatible
> +  - interrupts
> +  - reset-gpios
> +  - vdd-supply
> +  - input-report-header-address
> +  - input-report-body-address
> +  - output-report-address
> +  - read-opcode
> +  - write-opcode
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    #include <dt-bindings/interrupt-controller/irq.h>
> +    #include <dt-bindings/gpio/gpio.h>
> +
> +    spi {
> +      #address-cells = <1>;
> +      #size-cells = <0>;
> +
> +      hid@0 {
> +        compatible = "microsoft,g6-touch-digitizer", "hid-over-spi";
> +        reg = <0x0>;
> +        interrupts-extended = <&gpio 42 IRQ_TYPE_EDGE_FALLING>;
> +        reset-gpios = <&gpio 27 GPIO_ACTIVE_LOW>;
> +        vdd-supply = <&pm8350c_l3>;
> +        pinctrl-names = "default";
> +        pinctrl-0 = <&ts_d6_int_bias>;
> +        input-report-header-address = <0x1000>;
> +        input-report-body-address = <0x1004>;
> +        output-report-address = <0x2000>;
> +        read-opcode = /bits/ 8 <0x0b>;
> +        write-opcode = /bits/ 8 <0x02>;
> +      };
> +    };
> 
> -- 
> 2.53.0.1185.g05d4b7b318-goog
> 

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 228 bytes --]