Input: synaptics - fix device info appearing different on reconnect

User-modified input settings no longer survive a suspend/resume cycle.
Starting with 4.12, the touchpad is reinitialized on every reconnect
because the hardware appears to be different. This can be reproduced
by running the following as root:

    echo -n reconnect >/sys/devices/platform/i8042/serio1/drvctl

A line like the following will show up in dmesg:

    [30378.295794] psmouse serio1: synaptics: hardware appears to be
                   different: id(149271-149271), model(114865-114865),
                   caps(d047b3-d047b1), ext(b40000-b40000).

Note the single bit difference in caps: bit 1 (SYN_CAP_MULTIFINGER).

This happens because we modify our stored copy of the device info
capabilities when we enable advanced gesture mode but this change is
not reflected in the actual hardware capabilities.

It worked in the past because synaptics_query_hardware used to modify
the stored synaptics_device_info struct instead of filling in a new
one, as it does now.

Fix it by no longer faking the SYN_CAP_MULTIFINGER bit when setting
advanced gesture mode. This necessitated a small refactoring.

Fixes: 6c53694f ("Input: synaptics - split device info into a separate structure")
Signed-off-by: Anthony Martin <ality@pbrane.org>
Cc: stable@vger.kernel.org
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/mouse/synaptics.c

@@ -535,16 +535,17 @@ static void synaptics_apply_quirks(struct psmouse *psmouse,
 	}
 }
 
+static bool synaptics_has_agm(struct synaptics_data *priv)
+{
+	return (SYN_CAP_ADV_GESTURE(priv->info.ext_cap_0c) ||
+		SYN_CAP_IMAGE_SENSOR(priv->info.ext_cap_0c));
+}
+
 static int synaptics_set_advanced_gesture_mode(struct psmouse *psmouse)
 {
 	static u8 param = 0xc8;
-	struct synaptics_data *priv = psmouse->private;
 	int error;
 
-	if (!(SYN_CAP_ADV_GESTURE(priv->info.ext_cap_0c) ||
-	      SYN_CAP_IMAGE_SENSOR(priv->info.ext_cap_0c)))
-		return 0;
-
 	error = psmouse_sliced_command(psmouse, SYN_QUE_MODEL);
 	if (error)
 		return error;
@@ -553,9 +554,6 @@ static int synaptics_set_advanced_gesture_mode(struct psmouse *psmouse)
 	if (error)
 		return error;
 
-	/* Advanced gesture mode also sends multi finger data */
-	priv->info.capabilities |= BIT(1);
-
 	return 0;
 }
 
@@ -578,7 +576,7 @@ static int synaptics_set_mode(struct psmouse *psmouse)
 	if (error)
 		return error;
 
-	if (priv->absolute_mode) {
+	if (priv->absolute_mode && synaptics_has_agm(priv)) {
 		error = synaptics_set_advanced_gesture_mode(psmouse);
 		if (error) {
 			psmouse_err(psmouse,
@@ -766,9 +764,7 @@ static int synaptics_parse_hw_state(const u8 buf[],
 			 ((buf[0] & 0x04) >> 1) |
 			 ((buf[3] & 0x04) >> 2));
 
-		if ((SYN_CAP_ADV_GESTURE(priv->info.ext_cap_0c) ||
-			SYN_CAP_IMAGE_SENSOR(priv->info.ext_cap_0c)) &&
-		    hw->w == 2) {
+		if (synaptics_has_agm(priv) && hw->w == 2) {
 			synaptics_parse_agm(buf, priv, hw);
 			return 1;
 		}
@@ -1033,6 +1029,15 @@ static void synaptics_image_sensor_process(struct psmouse *psmouse,
 	synaptics_report_mt_data(psmouse, sgm, num_fingers);
 }
 
+static bool synaptics_has_multifinger(struct synaptics_data *priv)
+{
+	if (SYN_CAP_MULTIFINGER(priv->info.capabilities))
+		return true;
+
+	/* Advanced gesture mode also sends multi finger data */
+	return synaptics_has_agm(priv);
+}
+
 /*
  *  called for each full received packet from the touchpad
  */
@@ -1079,7 +1084,7 @@ static void synaptics_process_packet(struct psmouse *psmouse)
 		if (SYN_CAP_EXTENDED(info->capabilities)) {
 			switch (hw.w) {
 			case 0 ... 1:
-				if (SYN_CAP_MULTIFINGER(info->capabilities))
+				if (synaptics_has_multifinger(priv))
 					num_fingers = hw.w + 2;
 				break;
 			case 2:
@@ -1123,7 +1128,7 @@ static void synaptics_process_packet(struct psmouse *psmouse)
 		input_report_abs(dev, ABS_TOOL_WIDTH, finger_width);
 
 	input_report_key(dev, BTN_TOOL_FINGER, num_fingers == 1);
-	if (SYN_CAP_MULTIFINGER(info->capabilities)) {
+	if (synaptics_has_multifinger(priv)) {
 		input_report_key(dev, BTN_TOOL_DOUBLETAP, num_fingers == 2);
 		input_report_key(dev, BTN_TOOL_TRIPLETAP, num_fingers == 3);
 	}
@@ -1283,7 +1288,7 @@ static void set_input_params(struct psmouse *psmouse,
 	__set_bit(BTN_TOUCH, dev->keybit);
 	__set_bit(BTN_TOOL_FINGER, dev->keybit);
 
-	if (SYN_CAP_MULTIFINGER(info->capabilities)) {
+	if (synaptics_has_multifinger(priv)) {
 		__set_bit(BTN_TOOL_DOUBLETAP, dev->keybit);
 		__set_bit(BTN_TOOL_TRIPLETAP, dev->keybit);
 	}