Re: [PATCH RFC 1/3] dt-bindings: input: touchscreen: edt-ft5x06: Add wakeup gestures

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] dt-bindings: input: edt-ft5x06: event-* nodes encode OS policy in DT
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commit 6f5aa6f1554c8cb1ae88e2ea6e589e4befad85e1
Author: David Heidelberg <david@ixit.cz>

dt-bindings: input: touchscreen: edt-ft5x06: Add wakeup gestures

This patch adds event child nodes to the edt-ft5x06 touchscreen binding
to describe firmware wakeup gestures and map them to Linux input keycodes.

> diff --git a/Documentation/devicetree/bindings/input/touchscreen/edt-ft5x06.yaml b/Documentation/devicetree/bindings/input/touchscreen/edt-ft5x06.yaml
> index 68b2f16016543..bfc540665a2d2 100644
> --- a/Documentation/devicetree/bindings/input/touchscreen/edt-ft5x06.yaml
> +++ b/Documentation/devicetree/bindings/input/touchscreen/edt-ft5x06.yaml
> @@ -111,6 +111,25 @@ properties:
>  
>    interrupt-controller: true
>  
> +patternProperties:
> +  "^event-(tap-double|swipe-(up|down|left|right))$":
> +    type: object
> +    $ref: ../input.yaml#
> +    description:
> +      A gesture the controller keeps detecting in its gesture mode, reported
> +      as a key on a separate input device. Gesture mode is entered when the
> +      touchscreen input device is closed or the system suspends, provided
> +      the device may wake up the system. Only controllers whose firmware
> +      implements the gesture registers support these nodes.
> +
> +    properties:
> +      linux,code: true
> +
> +    required:
> +      - linux,code
> +
> +    additionalProperties: false

[Severity: Medium]
Do these event-(tap-double|swipe-(up|down|left|right)) child nodes encode
OS/userspace policy and Linux driver details rather than describing the
hardware?

Unlike physical buttons, printed touch-overlay segments (touch-overlay in
touchscreen.yaml), or trackpad controllers with per-gesture hardware
sensing and timing tuning registers (such as azoteq,iqs7211.yaml, which
configures hardware duration, distance, angle, and threshold registers per
gesture), a touchscreen panel has no board-specific physical wiring or
markings that determine whether double-tap or directional swipe wakeup
gestures exist or what keycode they map to.

Whether the touchscreen interrupt can wake the system is already described
by the standard wakeup-source property, and whether the controller
supports gesture detection is determined by the controller compatible and
firmware. Choosing which wakeup gestures are enabled during screen-off or
system suspend and which Linux keycode (such as KEY_WAKEUP) they emit is
runtime OS/userspace policy rather than static hardware description.

Furthermore, the description documents Linux driver implementation details
(reporting the gesture on a separate input device and entering gesture
mode when the touchscreen input device is closed or the system suspends),
whereas Documentation/devicetree/bindings/writing-bindings.rst specifies
that bindings should describe hardware rather than OS or device driver
behavior.

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Sashiko AI review · https://sashiko.dev/#/patchset/20261104-ft5x06-double-tap-v1-0-5a1bd80449cc@ixit.cz?part=1