Re: [PATCH v2 08/11] HID: hid-multitouch: fix Win 8 protocol

["Henrik Rydberg" <rydberg@euromail.se>]

On Fri, Oct 26, 2012 at 10:44:24AM +0200, Benjamin Tissoires wrote:
> Win 8 specification is much more precise than the Win 7 one.
> Moreover devices that need to take certification must be submitted
> to Microsoft.
> 
> The result is a better protocol support and we can rely on that to
> skip all the messy tests we used to do.
> 
> The protocol specify the fact that each valid touch must be reported
> within a frame, and that the release touch coordinate must be the
> same than the last known touch.
> So we can use the always_valid quirk and dismiss reports when we
> touch coordiante do not follow this rule.
> 
> Signed-off-by: Benjamin Tissoires <benjamin.tissoires@gmail.com>
> ---
>  drivers/hid/hid-multitouch.c | 16 ++++++++++++++--
>  1 file changed, 14 insertions(+), 2 deletions(-)

Why do we need this patch?

> diff --git a/drivers/hid/hid-multitouch.c b/drivers/hid/hid-multitouch.c
> index 43bd8e8..bd23f19 100644
> --- a/drivers/hid/hid-multitouch.c
> +++ b/drivers/hid/hid-multitouch.c
> @@ -510,6 +510,18 @@ static void mt_complete_slot(struct mt_device *td, struct input_dev *input)
>  		int slotnum = mt_compute_slot(td, input);
>  		struct mt_slot *s = &td->curdata;
>  
> +		if (td->mtclass.quirks & MT_QUIRK_WIN_8_CERTIFIED &&
> +		    !s->touch_state) {
> +			struct input_mt_slot *slot = &input->mt->slots[slotnum];
> +			int prv_x = input_mt_get_value(slot, ABS_MT_POSITION_X);
> +			int prv_y = input_mt_get_value(slot, ABS_MT_POSITION_Y);
> +			/* valid releases occurs when the last x and y positions
> +			 * are the same as the last known touch. */
> +			if (!input_mt_is_active(slot) ||
> +			    prv_x != s->x || prv_y != s->y)
> +				return;
> +		}
> +
>  		if (slotnum < 0 || slotnum >= td->maxcontacts)
>  			return;
>  
> @@ -681,8 +693,8 @@ static void mt_post_parse_default_settings(struct mt_device *td)
>  {
>  	__s32 quirks = td->mtclass.quirks;
>  
> -	/* unknown serial device needs special quirks */
> -	if (td->touches_by_report == 1) {
> +	/* unknown serial devices or win8 ones need special quirks */
> +	if (td->touches_by_report == 1 || quirks & MT_QUIRK_WIN_8_CERTIFIED) {
>  		quirks |= MT_QUIRK_ALWAYS_VALID;
>  		quirks &= ~MT_QUIRK_NOT_SEEN_MEANS_UP;
>  		quirks &= ~MT_QUIRK_VALID_IS_INRANGE;
> -- 
> 1.7.11.7
> 

Henrik