linux-kernel - Re: [PATCH v2 06/11] HID: hid-multitouch: support T and C for win8 devices

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Date:	Mon, 29 Oct 2012 23:00:58 +0100
From:	"Henrik Rydberg" <rydberg@...omail.se>
To:	Benjamin Tissoires <benjamin.tissoires@...il.com>
Cc:	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	Jiri Kosina <jkosina@...e.cz>,
	Stephane Chatty <chatty@...c.fr>, linux-input@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 06/11] HID: hid-multitouch: support T and C for win8
 devices

Hi Benjamin,

> Win8 input specification clarifies the X and Y sent by devices.
> It distincts the position where the user wants to Touch (T) from
> the center of the ellipsoide (C). This patch enable supports for this
> distinction in hid-multitouch.
> 
> We recognize Win8 certified devices from their vendor feature 0xff0000c5
> where Microsoft put a signed blob in the report to check if the device
> passed the certification.
> 
> Signed-off-by: Benjamin Tissoires <benjamin.tissoires@...il.com>
> ---
>  drivers/hid/hid-multitouch.c | 53 ++++++++++++++++++++++++++++++++++++--------
>  1 file changed, 44 insertions(+), 9 deletions(-)

This is great, just a few comments below.

> 
> diff --git a/drivers/hid/hid-multitouch.c b/drivers/hid/hid-multitouch.c
> index 41f2981..000c979 100644
> --- a/drivers/hid/hid-multitouch.c
> +++ b/drivers/hid/hid-multitouch.c
> @@ -52,9 +52,10 @@ MODULE_LICENSE("GPL");
>  #define MT_QUIRK_VALID_IS_CONFIDENCE	(1 << 6)
>  #define MT_QUIRK_SLOT_IS_CONTACTID_MINUS_ONE	(1 << 8)
>  #define MT_QUIRK_NO_AREA		(1 << 9)
> +#define MT_QUIRK_WIN_8_CERTIFIED	(1 << 10)
>  
>  struct mt_slot {
> -	__s32 x, y, p, w, h;
> +	__s32 x, y, cx, cy, p, w, h;
>  	__s32 contactid;	/* the device ContactID assigned to this slot */
>  	bool touch_state;	/* is the touch valid? */
>  };
> @@ -292,6 +293,10 @@ static void mt_feature_mapping(struct hid_device *hdev,
>  			td->maxcontacts = td->mtclass.maxcontacts;
>  
>  		break;
> +	case 0xff0000c5:
> +		if (field->report_count == 256 && field->report_size == 8)
> +			td->mtclass.quirks |= MT_QUIRK_WIN_8_CERTIFIED;
> +		break;
>  	}
>  }
>  
> @@ -350,18 +355,36 @@ static int mt_input_mapping(struct hid_device *hdev, struct hid_input *hi,
>  	case HID_UP_GENDESK:
>  		switch (usage->hid) {
>  		case HID_GD_X:
> -			hid_map_usage(hi, usage, bit, max,
> +			if (cls->quirks & MT_QUIRK_WIN_8_CERTIFIED &&

Parenthesis, please. Precedence is not always enough.

> +				usage_index) {
> +				hid_map_usage(hi, usage, bit, max,
> +					EV_ABS, ABS_MT_TOOL_X);
> +				set_abs(hi->input, ABS_MT_TOOL_X, field,
> +					cls->sn_move);
> +			} else {
> +				hid_map_usage(hi, usage, bit, max,
>  					EV_ABS, ABS_MT_POSITION_X);
> -			set_abs(hi->input, ABS_MT_POSITION_X, field,
> -				cls->sn_move);
> +				set_abs(hi->input, ABS_MT_POSITION_X, field,
> +					cls->sn_move);
> +			}
> +

Do we really want to do the latter several times, even if the device is not a win8 one?

>  			mt_store_field(usage, td, hi);
>  			td->last_field_index = field->index;
>  			return 1;
>  		case HID_GD_Y:
> -			hid_map_usage(hi, usage, bit, max,
> +			if (cls->quirks & MT_QUIRK_WIN_8_CERTIFIED &&

Ditto.

> +				usage_index) {
> +				hid_map_usage(hi, usage, bit, max,
> +					EV_ABS, ABS_MT_TOOL_Y);
> +				set_abs(hi->input, ABS_MT_TOOL_Y, field,
> +					cls->sn_move);
> +			} else {
> +				hid_map_usage(hi, usage, bit, max,
>  					EV_ABS, ABS_MT_POSITION_Y);
> -			set_abs(hi->input, ABS_MT_POSITION_Y, field,
> -				cls->sn_move);
> +				set_abs(hi->input, ABS_MT_POSITION_Y, field,
> +					cls->sn_move);
> +			}
> +

Ditto.

>  			mt_store_field(usage, td, hi);
>  			td->last_field_index = field->index;
>  			return 1;
> @@ -502,6 +525,12 @@ static void mt_complete_slot(struct mt_device *td, struct input_dev *input)
>  
>  			input_event(input, EV_ABS, ABS_MT_POSITION_X, s->x);
>  			input_event(input, EV_ABS, ABS_MT_POSITION_Y, s->y);
> +			if (td->mtclass.quirks & MT_QUIRK_WIN_8_CERTIFIED) {
> +				input_event(input, EV_ABS, ABS_MT_TOOL_X,
> +					s->cx);

Won't this fit on one line?

> +				input_event(input, EV_ABS, ABS_MT_TOOL_Y,
> +					s->cy);
> +			}
>  			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, major);
> @@ -553,10 +582,16 @@ static int mt_event(struct hid_device *hid, struct hid_field *field,
>  			td->curdata.p = value;
>  			break;
>  		case HID_GD_X:
> -			td->curdata.x = value;
> +			if (usage->code == ABS_MT_POSITION_X)
> +				td->curdata.x = value;
> +			else
> +				td->curdata.cx = value;

Since cx is the new value, reversing the logic would make sense here.

>  			break;
>  		case HID_GD_Y:
> -			td->curdata.y = value;
> +			if (usage->code == ABS_MT_POSITION_Y)
> +				td->curdata.y = value;
> +			else
> +				td->curdata.cy = value;
>  			break;
>  		case HID_DG_WIDTH:
>  			td->curdata.w = value;
> -- 
> 1.7.11.7
> 

Thanks,
Henrik
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