linux-kernel - Re: [PATCH v4] hid-multitouch: migrate 3M PCT touch screens to hid-multitouch

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Date:	Tue, 22 Mar 2011 17:58:15 +0100
From:	"Henrik Rydberg" <rydberg@...omail.se>
To:	Benjamin Tissoires <benjamin.tissoires@...c.fr>
Cc:	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	Jiri Kosina <jkosina@...e.cz>,
	Stephane Chatty <chatty@...-enac.fr>,
	linux-input@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4] hid-multitouch: migrate 3M PCT touch screens to
 hid-multitouch

On Tue, Mar 22, 2011 at 05:34:01PM +0100, Benjamin Tissoires wrote:
> This patch merges the hid-3m-pct driver into hid-multitouch.
> To keep devices working the same way they used to with hid-3m-pct,
> we need to add two signal/noise ratios for width and height.
> We also need to work on width/height to send proper
> ABS_MT_ORIENTATION flag.
> 
> Importing 3M into hid-multitouch also solved the bug in which
> devices handling width and height in their report descriptors
> did not show ABS_MT_TOUCH_MAJOR and ABS_MT_TOUCH_MINOR.
> 
> Signed-off-by: Benjamin Tissoires <benjamin.tissoires@...c.fr>
> Reviewed-by: Stéphane Chatty <chatty@...c.fr>
> ---
[...]
> Henrik, do I still have your Reviewed-and-tested-by ?

Yep, looks good. One more thing, though:

> @@ -332,11 +351,18 @@ static void mt_emit_event(struct mt_device *td, struct input_dev *input)
>  		input_mt_report_slot_state(input, MT_TOOL_FINGER,
>  			s->touch_state);
>  		if (s->touch_state) {
> +			/* this finger is on the screen */
> +			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;

This scaling is most likely not correct for all devices. I went
through a set of devices some time ago, running mtview on all of them,
visually inspecting the touch size. Some were low by a factor of two,
some were high by a factor of two. A confirmation that the other
devices supported by this driver seem right would be good. If not, a
quirk should probably be added here.

> +
>  			input_event(input, EV_ABS, ABS_MT_POSITION_X, s->x);
>  			input_event(input, EV_ABS, ABS_MT_POSITION_Y, s->y);
> +			input_event(input, EV_ABS, ABS_MT_ORIENTATION, wide);
>  			input_event(input, EV_ABS, ABS_MT_PRESSURE, s->p);
> -			input_event(input, EV_ABS, ABS_MT_TOUCH_MAJOR, s->w);
> -			input_event(input, EV_ABS, ABS_MT_TOUCH_MINOR, s->h);
> +			input_event(input, EV_ABS, ABS_MT_TOUCH_MAJOR, major);
> +			input_event(input, EV_ABS, ABS_MT_TOUCH_MINOR, minor);
>  		}
>  		s->seen_in_this_frame = false;

Thanks,
Henrik
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