# Re: \[PATCH 02/18\] Input: add FF\_HID effect type

- From: Harry Cutts \<hidden\>
- Date: 2021-12-30 16:42:01 
- List: linux-input
- Page: https://ratatoskr.run/linux-input/2021/12/8933744
- Thread: https://ratatoskr.run/linux-input/2021/12/8933714/t.md

```text
Hi Angela,

On Tue, 21 Dec 2021 at 11:17, Angela Czubak [ref] wrote:
>
> FF_HID effect type can be used to trigger haptic feedback with HID simple
> haptic usages.
>
> Signed-off-by: Angela Czubak <redacted>
> ---
>  include/uapi/linux/input.h | 22 +++++++++++++++++++++-
>  1 file changed, 21 insertions(+), 1 deletion(-)
>
> diff --git a/include/uapi/linux/input.h b/include/uapi/linux/input.h
> index ee3127461ee0..0d4d426cf75a 100644
> --- a/include/uapi/linux/input.h
> +++ b/include/uapi/linux/input.h
> @@ -424,6 +424,24 @@ struct ff_rumble_effect {
>         __u16 weak_magnitude;
>  };
>
> +/**
> + * struct ff_hid_effect
> + * @hid_usage: hid_usage according to Haptics page (WAVEFORM_CLICK, etc.)
> + * @vendor_id: the waveform vendor ID if hid_usage is in the vendor-defined range
> + * @vendor_id: the vendor waveform page if hid_usage is in the vendor-defined range

Looks like you forgot to change vendor_id to vendor_waveform_page on
the line above.

> + * @intensity: strength of the effect as percentage
> + * @repeat_count: number of times to retrigger effect
> + * @retrigger_period: time before effect is retriggered (in ms)
> + */
> +struct ff_hid_effect {
> +       __u16 hid_usage;
> +       __u16 vendor_id;
> +       __u8  vendor_waveform_page;
> +       __u16 intensity;
> +       __u16 repeat_count;
> +       __u16 retrigger_period;
> +};
> +
>  /**
>   * struct ff_effect - defines force feedback effect
>   * @type: type of the effect (FF_CONSTANT, FF_PERIODIC, FF_RAMP, FF_SPRING,
> @@ -460,6 +478,7 @@ struct ff_effect {
>                 struct ff_periodic_effect periodic;
>                 struct ff_condition_effect condition[2]; /* One for each axis */
>                 struct ff_rumble_effect rumble;
> +               struct ff_hid_effect hid;
>         } u;
>  };
>
> @@ -467,6 +486,7 @@ struct ff_effect {
>   * Force feedback effect types
>   */
>
> +#define FF_HID         0x4f
>  #define FF_RUMBLE      0x50
>  #define FF_PERIODIC    0x51
>  #define FF_CONSTANT    0x52
> @@ -476,7 +496,7 @@ struct ff_effect {
>  #define FF_INERTIA     0x56
>  #define FF_RAMP                0x57
>
> -#define FF_EFFECT_MIN  FF_RUMBLE
> +#define FF_EFFECT_MIN  FF_HID
>  #define FF_EFFECT_MAX  FF_RAMP
>
>  /*
> --
> 2.34.1.307.g9b7440fafd-goog
>

Harry Cutts
Chrome OS Touch/Input team
```