Input: wacom_w8001 - ignore invalid pen data packets

ThinkPad X60 Tablet PC (pen only device) sometime posts
packets that are larger than W8001_PKTLEN_TPCPEN.

Reported-by: Chris J Arges <christopherarges@gmail.com>
Tested-by: Chris J Arges <christopherarges@gmail.com>
Signed-off-by: Ping Cheng <pingc@wacom.com>
Reviewed-by: Peter Hutterer <peter.hutterer@who-t.net>
Cc: stable@vger.kernel.org
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

diff --git a/drivers/input/touchscreen/wacom_w8001.c b/drivers/input/touchscreen/wacom_w8001.c
index b1b412766da84448acb892fd11c4b45917793316..0c9191cf324d491ab25117ab654c6f1bf91375de 100644 (file)
--- a/drivers/input/touchscreen/wacom_w8001.c
+++ b/drivers/input/touchscreen/wacom_w8001.c
@@ -339,6 +339,15 @@ static irqreturn_t w8001_interrupt(struct serio *serio,
                w8001->idx = 0;
                parse_multi_touch(w8001);
                break;
+
+       default:
+               /*
+                * ThinkPad X60 Tablet PC (pen only device) sometimes
+                * sends invalid data packets that are larger than
+                * W8001_PKTLEN_TPCPEN. Let's start over again.
+                */
+               if (!w8001->touch_dev && w8001->idx > W8001_PKTLEN_TPCPEN - 1)
+                       w8001->idx = 0;
        }
 
        return IRQ_HANDLED;