Hi Seth,

On Thu, 18 Aug 2011 12:39:59 -0500, Seth Forshee [off-list ref] wrote:

On Thu, Aug 18, 2011 at 09:57:09AM +0800, JJ Ding wrote:

quoted

@@ -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.

Thank you for reporting this bug.
As for now, the following should fix this issue.
I will correct this in v2.
---

diff --git a/drivers/input/mouse/elantech.c b/drivers/input/mouse/elantech.c
index e13a719..fa842f7 100644
--- a/drivers/input/mouse/elantech.c
+++ b/drivers/input/mouse/elantech.c

@@ -410,11 +410,12 @@ static void elantech_report_absolute_v3(struct psmouse *psmouse,
                 * 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]);
+               y1 = ((packet[4] & 0x0f) << 8) | packet[5];
 
                if (fingers == 3 && debounce(x1, y1))
                        return;
 
+               y1 = etd->y_max - y1;
                break;
 
        case 2:
---

quoted

+
+/*
+ * 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.

AFAIK, though v2 and v3 differ in packet format, they really report the
same data to the userspace. In this version of v3 support, I even try to
make v2 and v3 report all the data in the same sequnce. If you're seeing
this issue, maybe we should do the same with v2?