Re: [PATCH 6/6] Input: elantech - add v3 hardware support

[JJ Ding <jj_ding@emc.com.tw>]

Hi Éric,

Thanks for your comments, a few lines below:

On Fri, 19 Aug 2011 15:03:04 +0200, Éric Piel <E.A.B.Piel@tudelft.nl> wrote:
> Op 18-08-11 03:57, JJ Ding schreef:
> > v3 hardware's packet format is almost identical to v2 (one/three finger touch),
> > except when sensing two finger touch, the hardware sends 12 bytes of data.
> >
> > Signed-off-by: JJ Ding<jj_ding@emc.com.tw>
> Hi,
> A couple of comments, in line.
> 
> :
> :
> > diff --git a/drivers/input/mouse/elantech.c b/drivers/input/mouse/elantech.c
> > index ddd40eb..e13a719 100644
> > --- a/drivers/input/mouse/elantech.c
> > +++ b/drivers/input/mouse/elantech.c
> :
> > +/*
> > + * Interpret complete data packets and report absolute mode input events for
> > + * hardware version 3. (12 byte packets for two fingers)
> > + */
> > +static void elantech_report_absolute_v3(struct psmouse *psmouse,
> > +					int packet_type)
> > +{
> > +	struct input_dev *dev = psmouse->dev;
> > +	struct elantech_data *etd = psmouse->private;
> > +	unsigned char *packet = psmouse->packet;
> > +	unsigned int fingers = 0, x1 = 0, y1 = 0, x2 = 0, y2 = 0;
> > +	unsigned int width = 0, pres = 0;
> > +
> > +	/* byte 0: n1  n0   .   .   .   .   R   L */
> > +	fingers = (packet[0]&  0xc0)>>  6;
> > +
> > +	switch (fingers) {
> > +	case 3:
> > +	case 1:
> > +		/*
> > +		 * byte 1:  .   .   .   .  x11 x10 x9  x8
> > +		 * byte 2: x7  x6  x5  x4  x4  x2  x1  x0
> > +		 */
> > +		x1 = ((packet[1]&  0x0f)<<  8) | packet[2];
> > +		/*
> > +		 * byte 4:  .   .   .   .  y11 y10 y9  y8
> > +		 * byte 5: y7  y6  y5  y4  y3  y2  y1  y0
> > +		 */
> > +		y1 = etd->y_max - (((packet[4]&  0x0f)<<  8) | packet[5]);
> > +
> > +		if (fingers == 3&&  debounce(x1, y1))
> > +			return;
> > +
> > +		break;
> > +
> > +	case 2:
> > +		if (packet_type == PACKET_V3_HEAD) {
> > +			/*
> > +			 * byte 1:   .    .    .    .  ax11 ax10 ax9  ax8
> > +			 * byte 2: ax7  ax6  ax5  ax4  ax3  ax2  ax1  ax0
> > +			 */
> > +			etd->prev_x = ((packet[1]&  0x0f)<<  8) | packet[2];
> > +			/*
> > +			 * byte 4:   .    .    .    .  ay11 ay10 ay9  ay8
> > +			 * byte 5: ay7  ay6  ay5  ay4  ay3  ay2  ay1  ay0
> > +			 */
> > +			etd->prev_y = etd->y_max -
> > +				(((packet[4]&  0x0f)<<  8) | packet[5]);
> > +			/*
> > +			 * wait for next packet
> > +			 */
> > +			return;
> > +		}
> > +
> > +		/* packet_type == PACKET_V3_TAIL */
> > +		x1 = etd->prev_x;
> > +		y1 = etd->prev_y;
> > +		x2 = ((packet[1]&  0x0f)<<  8) | packet[2];
> > +		y2 = etd->y_max - (((packet[4]&  0x0f)<<  8) | packet[5]);
> > +		break;
> > +	}
> You actually have three times the same formula, so you could simplify it:
> 
> if (fingers !=0 ) {
> 	/*
> 	 * byte 1:  .   .   .   .  x11 x10 x9  x8
> 	 * byte 2: x7  x6  x5  x4  x4  x2  x1  x0
> 	 */
> 	x1 = ((packet[1]&  0x0f)<<  8) | packet[2];
> 	/*
> 	 * byte 4:  .   .   .   .  y11 y10 y9  y8
> 	 * byte 5: y7  y6  y5  y4  y3  y2  y1  y0
> 	 */
> 	y1 = ((packet[4]&  0x0f)<<  8) | packet[5];
> }
> 
> if ((fingers == 3) && debounce(x1, y1))
> 	return;
we need one more line here, for fingers != 2 :
y1 = etd->y_max - y1;
> if (fingers == 2) {
> 	if (packet_type == PACKET_V3_HEAD)) {
> 		/* wait for next packet */
> 		etd->prev_x = x1;
> 		etd->prev_y = etd->y_max - y1;
                etd->prev_y = y1;
> 		return;
> 	} else {
> 		/* packet_type == PACKET_V3_TAIL */
> 		x2 = etd->prev_x;
> 		y2 = etd->prev_y;
> 	}
> }
I like this compact version, but it seems to me this is not as straight
forward as the original switch case. I am OK with either. Is there
anyone who has more to say about this?
> 
> > +
> > +	pres = (packet[1]&  0xf0) | ((packet[4]&  0xf0)>>  4);
> > +	width = ((packet[0]&  0x30)>>  2) | ((packet[3]&  0x30)>>  4);
> What about the case of two fingers? Are pressure and width correct for 
> both fingers? In that case, maybe it should also be saved from 
> PACKET_V3_HEAD.
I am told (by our firmware guy) that pres and width are sent the same
value for two finger touch.
> 
> > +
> > +	input_report_key(dev, BTN_TOUCH, fingers != 0);
> > +	input_report_abs(dev, ABS_X, x1);
> > +	input_report_abs(dev, ABS_Y, y1);
> > +	elantech_report_semi_mt_data(dev, fingers, x1, y1, x2, y2);
> > +	input_report_key(dev, BTN_TOOL_FINGER, fingers == 1);
> > +	input_report_key(dev, BTN_TOOL_DOUBLETAP, fingers == 2);
> > +	input_report_key(dev, BTN_TOOL_TRIPLETAP, fingers == 3);
> > +	input_report_key(dev, BTN_LEFT, packet[0]&  0x01);
> > +	input_report_key(dev, BTN_RIGHT, packet[0]&  0x02);
> > +	input_report_abs(dev, ABS_PRESSURE, pres);
> > +	input_report_abs(dev, ABS_TOOL_WIDTH, width);
> > +
> > +	input_sync(dev);
> > +}
> > +
> :
> >
> >   /*
> >    * Set the appropriate event bits for the input subsystem
> >    */
> > -static void elantech_set_input_params(struct psmouse *psmouse)
> > +static int elantech_set_input_params(struct psmouse *psmouse)
> >   {
> >   	struct input_dev *dev = psmouse->dev;
> >   	struct elantech_data *etd = psmouse->private;
> >   	unsigned int x_min = 0, y_min = 0, x_max = 0, y_max = 0, y_2ft_max = 0;
> >
> > -	set_range(psmouse,&x_min,&y_min,&x_max,&y_max,&y_2ft_max);
> > +	if (set_range(psmouse,&x_min,&y_min,&x_max,&y_max,&y_2ft_max))
> > +		return -1;
> >
> >   	__set_bit(EV_KEY, dev->evbit);
> >   	__set_bit(EV_ABS, dev->evbit);
> > @@ -582,10 +739,26 @@ static void elantech_set_input_params(struct psmouse *psmouse)
> >   		input_set_abs_params(dev, ABS_MT_POSITION_X, x_min, x_max, 0, 0);
> >   		input_set_abs_params(dev, ABS_MT_POSITION_Y, y_min, y_max, 0, 0);
> >   		break;
> > +
> > +	case 3:
> > +		input_set_abs_params(dev, ABS_X, x_min, x_max, 0, 0);
> > +		input_set_abs_params(dev, ABS_Y, y_min, y_max, 0, 0);
> > +		/* range of pressure and width is the same as v2 */
> > +		input_set_abs_params(dev, ABS_PRESSURE, ETP_PMIN_V2,
> > +				     ETP_PMAX_V2, 0, 0);
> > +		input_set_abs_params(dev, ABS_TOOL_WIDTH, ETP_WMIN_V2,
> > +				     ETP_WMAX_V2, 0, 0);
> > +		__set_bit(INPUT_PROP_SEMI_MT, dev->propbit);
> Does v3 have the same limitation in MT about only reporting the edges of 
> the bounding box? Or are the two fingers always reported independently? 
> If that is so, you can drop this line :-)
I suppose it's the same as v2, but I have to comfirm with our firmware team.
I will ckeck this.
> 
> > +		input_mt_init_slots(dev, 2);
> > +		input_set_abs_params(dev, ABS_MT_POSITION_X, x_min, x_max, 0, 0);
> > +		input_set_abs_params(dev, ABS_MT_POSITION_Y, y_min, y_max, 0, 0);
> > +		break;
> >   	}
> >
> 
> Cheers,
> Éric
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