Re: [PATCH 09/12] dt-bindings: input: Document hid-over-spi DT schema

[Dmitry Torokhov]

On Sat, Mar 07, 2026 at 04:25:44AM -0300, Val Packett wrote:
> 
> On 3/3/26 3:13 AM, 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.
> > […]
> > +properties:
> > +  compatible:
> > +    oneOf:
> > +      - items:
> > +          - enum:
> > +              - microsoft,g6-touch-digitizer
> > +          - const: hid-over-spi
> > +      - description: Just "hid-over-spi" alone is allowed, but not recommended.
> > […]
> > +required:
> > +  - compatible
> > +  - interrupts
> > +  - reset-gpios
> 
> Why is reset required? Is it so implausible on some device implementing the
> spec there wouldn't be a reset gpio?

No, because it is mandated by the spec:

"HID SPI peripheral must provide a dedicated reset line, driven by the
HOST, which, when toggled (pulled LOW for at least 10ms, normally HIGH),
will have the effect of resetting the device. If a HID SPI peripheral is
enumerated via ACPI, the device ASL configuration must expose an ACPI
FLDR (_RST) method to control this line."

The spec also states that the host must initiate reset during
initialization of the device.

> 
> > +  - vdd-supply
> Linux makes up a dummy regulator if DT doesn't provide one, so can
> regulators even be required?

There is still a supply line to the chip even if it is not exposed to
the OS control. So as far as chip is concerned the supply is required.

Thanks.

-- 
Dmitry