[PATCH] alps: Only Dell laptops have separate button bits for v2 dualpoint sticks

[PATCH] alps: Only Dell laptops have separate button bits for v2 dualpoint sticks

[Hans de Goede]

It turns out that only Dell laptops have the separate button bits for
v2 dualpoint sticks and that commit 92bac83dd79e ("Input: alps - non
interleaved V2 dualpoint has separate stick button bits") causes
regressions on Toshiba laptops.

This commit adds a check for Dell laptops to the code for handling these
extra button bits, fixing this regression.

This patch has been tested on a Dell Latitude D620 to make sure that it
does not reintroduce the original problem.

Reported-and-tested-by: Douglas Christman <douglaschristman@gmail.com>
Cc: Douglas Christman <douglaschristman@gmail.com>
Cc: stable@vger.kernel.org
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
 Documentation/input/alps.txt | 6 ++++--
 drivers/input/mouse/alps.c   | 8 ++++++--
 2 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/Documentation/input/alps.txt b/Documentation/input/alps.txt
index c86f2f1..1fec113 100644
--- a/Documentation/input/alps.txt
+++ b/Documentation/input/alps.txt
@@ -119,8 +119,10 @@ ALPS Absolute Mode - Protocol Version 2
  byte 5:  0   z6   z5   z4   z3   z2   z1   z0
 
 Protocol Version 2 DualPoint devices send standard PS/2 mouse packets for
-the DualPoint Stick. For non interleaved dualpoint devices the pointingstick
-buttons get reported separately in the PSM, PSR and PSL bits.
+the DualPoint Stick. The M, R and L bits signal the combined status of both
+the pointingstick and touchpad buttons, except for Dell dualpoint devices
+where the pointingstick buttons get reported separately in the PSM, PSR
+and PSL bits.
 
 Dualpoint device -- interleaved packet format
 ---------------------------------------------
diff --git a/drivers/input/mouse/alps.c b/drivers/input/mouse/alps.c
index 113d6f1..4d24686 100644
--- a/drivers/input/mouse/alps.c
+++ b/drivers/input/mouse/alps.c
@@ -20,6 +20,7 @@
 #include <linux/input/mt.h>
 #include <linux/serio.h>
 #include <linux/libps2.h>
+#include <linux/dmi.h>
 
 #include "psmouse.h"
 #include "alps.h"
@@ -99,6 +100,7 @@ static const struct alps_nibble_commands alps_v6_nibble_commands[] = {
 #define ALPS_FOUR_BUTTONS	0x40	/* 4 direction button present */
 #define ALPS_PS2_INTERLEAVED	0x80	/* 3-byte PS/2 packet interleaved with
 					   6-byte ALPS packet */
+#define ALPS_DELL		0x100	/* device is a Dell laptop */
 #define ALPS_BUTTONPAD		0x200	/* device is a clickpad */
 
 static const struct alps_model_info alps_model_data[] = {
@@ -251,9 +253,9 @@ static void alps_process_packet_v1_v2(struct psmouse *psmouse)
 		return;
 	}
 
-	/* Non interleaved V2 dualpoint has separate stick button bits */
+	/* Dell non interleaved V2 dualpoint has separate stick button bits */
 	if (priv->proto_version == ALPS_PROTO_V2 &&
-	    priv->flags == (ALPS_PASS | ALPS_DUALPOINT)) {
+	    priv->flags == (ALPS_DELL | ALPS_PASS | ALPS_DUALPOINT)) {
 		left |= packet[0] & 1;
 		right |= packet[0] & 2;
 		middle |= packet[0] & 4;
@@ -2550,6 +2552,8 @@ static int alps_set_protocol(struct psmouse *psmouse,
 	priv->byte0 = protocol->byte0;
 	priv->mask0 = protocol->mask0;
 	priv->flags = protocol->flags;
+	if (dmi_name_in_vendors("Dell"))
+		priv->flags |= ALPS_DELL;
 
 	priv->x_max = 2000;
 	priv->y_max = 1400;
-- 
2.4.3