Input: ALPS - fix touchpad detection when buttons are pressed

commit 99c90ab3 upstream.

ALPS touchpad detection fails if some buttons of ALPS are pressed.
The reason is that the "E6" query response byte is different from
what is expected.

This was tested on a Toshiba Portege R500.
Signed-off-by: Akio Idehara <zbe64533@gmail.com>
Tested-by: Seth Forshee <seth.forshee@canonical.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/input/mouse/alps.c

@@ -421,7 +421,9 @@ static const struct alps_model_info *alps_get_model(struct psmouse *psmouse, int
 
 	/*
 	 * First try "E6 report".
-	 * ALPS should return 0,0,10 or 0,0,100
+	 * ALPS should return 0,0,10 or 0,0,100 if no buttons are pressed.
+	 * The bits 0-2 of the first byte will be 1s if some buttons are
+	 * pressed.
 	 */
 	param[0] = 0;
 	if (ps2_command(ps2dev, param, PSMOUSE_CMD_SETRES) ||
@@ -437,7 +439,8 @@ static const struct alps_model_info *alps_get_model(struct psmouse *psmouse, int
 	psmouse_dbg(psmouse, "E6 report: %2.2x %2.2x %2.2x",
 		    param[0], param[1], param[2]);
 
-	if (param[0] != 0 || param[1] != 0 || (param[2] != 10 && param[2] != 100))
+	if ((param[0] & 0xf8) != 0 || param[1] != 0 ||
+	    (param[2] != 10 && param[2] != 100))
 		return NULL;
 
 	/*