linux-kernel - Re: [PATCH] HID: hid-multitouch: change for touch height/width

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Date:   Mon, 6 Mar 2017 09:24:50 +0100
From:   Benjamin Tissoires <benjamin.tissoires@...hat.com>
To:     hn.chen@...dahitech.com
Cc:     linux-input@...r.kernel.org, linux-kernel@...r.kernel.org,
        dmitry.torokhov@...il.com, jonathan.a.clarke@...il.com,
        jikos@...nel.org
Subject: Re: [PATCH] HID: hid-multitouch: change for touch height/width

On Mar 06 2017 or thereabouts, hn.chen@...dahitech.com wrote:
> From: HungNien Chen <hn.chen@...dahitech.com>
> 
> Just quote from Jonathan Clarke in previous thread(2017/01/24):
> "This division by 2 was added along with the touch width/height
> fields 6 years ago so that those fields 'match the visual scale
> of the touch' for a specific device (3M PCT)"
> "The scaling is also discarding information about touch size
> (1 bit for each of width/height) which is useful for any
> application that wants to know about it."
> 
> Jonathan mentioned just what I thought in a new project recently.
> It dosen't make sense to discard 1 bit width/height in general
> case according to the spec in multi-touch-protocol.txt so
> I would like to make a slight change here.
> 
> A quirk MT_QUIRK_TOUCH_SIZE_SCALING was added to service
> devices like 3M PCT with a special visual scale and
> the division by 2 only take effect with devices like that.
> 
> Signed-off-by: HungNien Chen <hn.chen@...dahitech.com>
> ---

Looks good to me:

Reviewed-by: Benjamin Tissoires <benjamin.tissoires@...hat.com>

Thanks for the respin.

Cheers,
Benjamin

>  drivers/hid/hid-multitouch.c | 18 ++++++++++++++----
>  1 file changed, 14 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/hid/hid-multitouch.c b/drivers/hid/hid-multitouch.c
> index 6926474..24d5b6d 100644
> --- a/drivers/hid/hid-multitouch.c
> +++ b/drivers/hid/hid-multitouch.c
> @@ -69,6 +69,7 @@
>  #define MT_QUIRK_CONTACT_CNT_ACCURATE	(1 << 12)
>  #define MT_QUIRK_FORCE_GET_FEATURE	(1 << 13)
>  #define MT_QUIRK_FIX_CONST_CONTACT_ID	(1 << 14)
> +#define MT_QUIRK_TOUCH_SIZE_SCALING	(1 << 15)
>  
>  #define MT_INPUTMODE_TOUCHSCREEN	0x02
>  #define MT_INPUTMODE_TOUCHPAD		0x03
> @@ -222,7 +223,8 @@ static int cypress_compute_slot(struct mt_device *td)
>  	 */
>  	{ .name = MT_CLS_3M,
>  		.quirks = MT_QUIRK_VALID_IS_CONFIDENCE |
> -			MT_QUIRK_SLOT_IS_CONTACTID,
> +			MT_QUIRK_SLOT_IS_CONTACTID |
> +			MT_QUIRK_TOUCH_SIZE_SCALING,
>  		.sn_move = 2048,
>  		.sn_width = 128,
>  		.sn_height = 128,
> @@ -658,9 +660,17 @@ static void mt_complete_slot(struct mt_device *td, struct input_dev *input)
>  		if (active) {
>  			/* this finger is in proximity of the sensor */
>  			int wide = (s->w > s->h);
> -			/* divided by two to match visual scale of touch */
> -			int major = max(s->w, s->h) >> 1;
> -			int minor = min(s->w, s->h) >> 1;
> +			int major = max(s->w, s->h);
> +			int minor = min(s->w, s->h);
> +
> +			/*
> +			 * divided by two to match visual scale of touch
> +			 * for devices with this quirk
> +			 */
> +			if (td->mtclass.quirks & MT_QUIRK_TOUCH_SIZE_SCALING) {
> +				major = major >> 1;
> +				minor = minor >> 1;
> +			}
>  
>  			input_event(input, EV_ABS, ABS_MT_POSITION_X, s->x);
>  			input_event(input, EV_ABS, ABS_MT_POSITION_Y, s->y);
> -- 
> 1.9.1
>