Input: ALPS - fix touchpad detection when buttons are pressed

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.

Cc: stable <stable@vger.kernel.org>
Signed-off-by: Akio Idehara <zbe64533@gmail.com>
Tested-by: Seth Forshee <seth.forshee@canonical.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

2 files changed, 7 insertions, 3 deletions

diff --git a/Documentation/input/alps.txt b/Documentation/input/alps.txt
index f274c28b5103..2f95308251d4 100644
--- a/Documentation/input/alps.txt
+++ b/Documentation/input/alps.txt
@@ -13,7 +13,8 @@ Detection
 
 All ALPS touchpads should respond to the "E6 report" command sequence:
 E8-E6-E6-E6-E9. An ALPS touchpad should respond with either 00-00-0A or
-00-00-64.
+00-00-64 if no buttons are pressed. The bits 0-2 of the first byte will be 1s
+if some buttons are pressed.
 
 If the E6 report is successful, the touchpad model is identified using the "E7
 report" sequence: E8-E7-E7-E7-E9. The response is the model signature and is
diff --git a/drivers/input/mouse/alps.c b/drivers/input/mouse/alps.c
index bd87380bd879..4c6a72d3d48c 100644
--- a/drivers/input/mouse/alps.c
+++ b/drivers/input/mouse/alps.c
@@ -952,7 +952,9 @@ 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) ||
@@ -968,7 +970,8 @@ 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;
 
         /*