linux-kernel - Re: [PATCH 6/6] Input: elantech

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Date:	Thu, 18 Aug 2011 12:39:59 -0500
From:	Seth Forshee <seth.forshee@...onical.com>
To:	JJ Ding <jj_ding@....com.tw>
Cc:	linux-input@...r.kernel.org, linux-kernel@...r.kernel.org,
	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	Aaron Huang <aaron_huang@....com.tw>,
	Tom Lin <tom_lin@....com.tw>,
	Eric Piel <E.A.B.Piel@...elft.nl>,
	Daniel Kurtz <djkurtz@...omium.org>,
	Chase Douglas <chase.douglas@...onical.com>,
	Henrik Rydberg <rydberg@...omail.se>,
	Alessandro Rubini <rubini@...l.unipv.it>
Subject: Re: [PATCH 6/6] Input: elantech - add v3 hardware support

On Thu, Aug 18, 2011 at 09:57:09AM +0800, JJ Ding wrote:
> @@ -352,6 +374,94 @@ static void elantech_report_absolute_v2(struct psmouse *psmouse)
>  	input_sync(dev);
>  }
>  
> +/*
> + * firmware tells us there's noise.
> + */
> +static inline int debounce(unsigned int x, unsigned int y)
> +{
> +	return (x == 0xfff) && (y == 0xfff);
> +}

This is problematic in my testing, in two ways.

First, it never actually triggers, because the y values passed to it are
not the raw data from the packets and as such are not 0xfff anymore in
the cases you're trying to detect.

Second, I get these packets with 1 and 2 finger touches on the Samsung
NF310, but you only check it in the 3 finger case.

As a result, I'm getting some reports with negative values for the y
position.

> +
> +/*
> + * 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;
> +	}
> +
> +	pres = (packet[1] & 0xf0) | ((packet[4] & 0xf0) >> 4);
> +	width = ((packet[0] & 0x30) >> 2) | ((packet[3] & 0x30) >> 4);
> +
> +	input_report_key(dev, BTN_TOUCH, fingers != 0);
> +	input_report_abs(dev, ABS_X, x1);
> +	input_report_abs(dev, ABS_Y, y1);

You should only report the ABS_[XY] coordinates when fingers != 0. The
xorg synaptics module sees the values reported in that case as
legitimate. This is causing me to see strange behaviors when scrolling
with two-finger drags.
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