psmouse.c: First check for a Synaptics touchpad, other probes confuse

it enough to disable the trackpoint.

drivers/input/mouse/psmouse.c

@@ -311,6 +311,26 @@ static int psmouse_extensions(struct psmouse *psmouse)
 	if (psmouse_noext)
 		return PSMOUSE_PS2;
 
+/*
+ * Try Synaptics TouchPad magic ID
+ */
+
+       param[0] = 0;
+       psmouse_command(psmouse, param, PSMOUSE_CMD_SETRES);
+       psmouse_command(psmouse, param, PSMOUSE_CMD_SETRES);
+       psmouse_command(psmouse, param, PSMOUSE_CMD_SETRES);
+       psmouse_command(psmouse, param, PSMOUSE_CMD_SETRES);
+       psmouse_command(psmouse, param, PSMOUSE_CMD_GETINFO);
+
+       if (param[1] == 0x47) {
+               /* We could do more here. But it's sufficient just
+                  to stop the subsequent probes from screwing the
+                  thing up. */
+               psmouse->vendor = "Synaptics";
+               psmouse->name = "TouchPad";
+               return PSMOUSE_PS2;
+       }
+
 /*
  * Try Genius NetMouse magic init.
  */