[PATCH 3.2 026/164] Input: elantech - fix absolute mode setting on some ASUS laptops

[Ben Hutchings]

3.2.70-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Ulrik De Bie <ulrik.debie-os@xxxxxxxxx>

commit bd884149aca61de269fd9bad83fe2a4232ffab21 upstream.

On ASUS TP500LN and X750JN, the touchpad absolute mode is reset each
time set_rate is done.

In order to fix this, we will verify the firmware version, and if it
matches the one in those laptops, the set_rate function is overloaded
with a function elantech_set_rate_restore_reg_07 that performs the
set_rate with the original function, followed by a restore of reg_07
(the register that sets the absolute mode on elantech v4 hardware).

Also the ASUS TP500LN and X750JN firmware version, capabilities, and
button constellation is added to elantech.c

Reported-and-tested-by: George Moutsopoulos <gmoutso@xxxxxxxxxxx>
Signed-off-by: Ulrik De Bie <ulrik.debie-os@xxxxxxxxx>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx>
[bwh: Backported to 3.2:
 - Adjust context
 - Drop the insertion into a comment we don't have]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
--- a/drivers/input/mouse/elantech.c
+++ b/drivers/input/mouse/elantech.c
@@ -766,6 +766,21 @@ static psmouse_ret_t elantech_process_by
 }
 
 /*
+ * This writes the reg_07 value again to the hardware at the end of every
+ * set_rate call because the register loses its value. reg_07 allows setting
+ * absolute mode on v4 hardware
+ */
+static void elantech_set_rate_restore_reg_07(struct psmouse *psmouse,
+		unsigned int rate)
+{
+	struct elantech_data *etd = psmouse->private;
+
+	etd->original_set_rate(psmouse, rate);
+	if (elantech_write_reg(psmouse, 0x07, etd->reg_07))
+		psmouse_err(psmouse, "restoring reg_07 failed\n");
+}
+
+/*
  * Put the touchpad into absolute mode
  */
 static int elantech_set_absolute_mode(struct psmouse *psmouse)
@@ -1353,6 +1368,11 @@ int elantech_init(struct psmouse *psmous
 		goto init_fail;
 	}
 
+	if (etd->fw_version == 0x381f17) {
+		etd->original_set_rate = psmouse->set_rate;
+		psmouse->set_rate = elantech_set_rate_restore_reg_07;
+	}
+
 	if (elantech_set_input_params(psmouse)) {
 		psmouse_err(psmouse, "failed to query touchpad range.\n");
 		goto init_fail;
--- a/drivers/input/mouse/elantech.h
+++ b/drivers/input/mouse/elantech.h
@@ -136,6 +136,7 @@ struct elantech_data {
 	unsigned int width;
 	struct finger_pos mt[ETP_MAX_FINGERS];
 	unsigned char parity[256];
+	void (*original_set_rate)(struct psmouse *psmouse, unsigned int rate);
 };
 
 #ifdef CONFIG_MOUSE_PS2_ELANTECH

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