Re: [PATCH v2 1/2] dt-bindings: input: hid-over-i2c: Add reset-gpios property

[Hans de Goede]

Hi,

On 22-May-26 21:55, Pradyot Kumar Nayak wrote:
> Document reset-gpios property for devices that explicitly require
> the reset line to be de-asserted during power up.
> 
> Signed-off-by: Pradyot Kumar Nayak <pradyot.nayak@xxxxxxxxxxxxxxxx>
> ---
>  Documentation/devicetree/bindings/input/hid-over-i2c.yaml | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/input/hid-over-i2c.yaml b/Documentation/devicetree/bindings/input/hid-over-i2c.yaml
> index 138caad96a29..fe0ec4fce673 100644
> --- a/Documentation/devicetree/bindings/input/hid-over-i2c.yaml
> +++ b/Documentation/devicetree/bindings/input/hid-over-i2c.yaml
> @@ -50,6 +50,10 @@ properties:
>      description: Time required by the device after enabling its regulators
>        or powering it on, before it is ready for communication.
>  
> +  reset-gpios:
> +    maxItems: 1
> +    description: GPIO line used to reset the device.
> +

For I2C HID devices which need a reset, we typically also
need reset timings, trying to do I2C transfers to the device directly
after the reset has been de-asserted typically will not work and
some touchscreen-model specific delay is necessary.

So far in the DT world this has been handled by touchscreen
vendor specific bindings:

Documentation/devicetree/bindings/input/elan,ekth6915.yaml
Documentation/devicetree/bindings/input/focaltech,ft8112.yaml
Documentation/devicetree/bindings/input/ilitek,ili9882t.yaml

Which are all 3 handled by:

drivers/hid/i2c-hid/i2c-hid-of-elan.c

Which has per compatible match-data with the reset timings.

You should probably extend drivers/hid/i2c-hid/i2c-hid-of-elan.c
with support for the CRD touchscreen and either add a new
compatible to one of the existing 3 bindings; or if the touchscreen
controller IC is from a vendor without a binding yet maybe add
a new bindings file?

There also is:

Documentation/devicetree/bindings/input/goodix,gt7375p.yaml

which is handled by:

drivers/hid/i2c-hid/i2c-hid-of-goodix.c

and is special in its own way.

Regards,

Hans