Re: [PATCH 11/18] HID: input: calculate resolution for pressure

[Dmitry Torokhov <dmitry.torokhov@gmail.com>]

On Tue, Dec 21, 2021 at 07:17:36PM +0000, Angela Czubak wrote:
> Assume that if the pressure is given in newtons it should be normalized
> to grams. If the pressure has no unit do not calculate resolution.
> 
> Signed-off-by: Angela Czubak <acz@semihalf.com>
> ---
>  drivers/hid/hid-input.c | 13 +++++++++++++
>  1 file changed, 13 insertions(+)
> 
> diff --git a/drivers/hid/hid-input.c b/drivers/hid/hid-input.c
> index 81eb277dee91..b680641a30c0 100644
> --- a/drivers/hid/hid-input.c
> +++ b/drivers/hid/hid-input.c
> @@ -257,6 +257,19 @@ __s32 hidinput_calc_abs_res(const struct hid_field *field, __u16 code)
>  		}
>  		break;
>  
> +	case ABS_PRESSURE:
> +	case ABS_MT_PRESSURE:
> +		if (field->unit == 0xe111) {		/* If newtons */

Using a named constant would be great.

> +			/* Convert to grams */

If you could add to the comment that 1 newton is 101.97 grams that would
be great.

> +			prev = physical_extents;
> +			physical_extents *= 10197;
> +			if (physical_extents < prev)
> +				return 0;
> +			unit_exponent -= 2;
> +		} else if (field->unit != 0x101) {	/* If not grams */
> +			return 0;
> +		}
> +		break;
>  	default:
>  		return 0;
>  	}
> -- 
> 2.34.1.307.g9b7440fafd-goog
> 

Thanks.

-- 
Dmitry