From c34120aafab9094d4bdc1f9e6838a13c6ec54159 Mon Sep 17 00:00:00 2001 From: =?utf8?q?Pali=20Roh=C3=A1r?= Date: Sat, 8 Nov 2014 12:58:57 -0800 Subject: [PATCH] Input: alps - allow up to 2 invalid packets without resetting device MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit commit 9d720b34c0a432639252f63012e18b0507f5b432 upstream. On some Dell Latitude laptops ALPS device or Dell EC send one invalid byte in 6 bytes ALPS packet. In this case psmouse driver enter out of sync state. It looks like that all other bytes in packets are valid and also device working properly. So there is no need to do full device reset, just need to wait for byte which match condition for first byte (start of packet). Because ALPS packets are bigger (6 or 8 bytes) default limit is small. This patch increase number of invalid bytes to size of 2 ALPS packets which psmouse driver can drop before do full reset. Resetting ALPS devices take some time and when doing reset on some Dell laptops touchpad, trackstick and also keyboard do not respond. So it is better to do it only if really necessary. Signed-off-by: Pali Rohár Tested-by: Pali Rohár Reviewed-by: Hans de Goede Signed-off-by: Dmitry Torokhov Signed-off-by: Greg Kroah-Hartman --- drivers/input/mouse/alps.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/input/mouse/alps.c b/drivers/input/mouse/alps.c index 873c0e0..fdffac9 100644 --- a/drivers/input/mouse/alps.c +++ b/drivers/input/mouse/alps.c @@ -2154,6 +2154,9 @@ int alps_init(struct psmouse *psmouse) /* We are having trouble resyncing ALPS touchpads so disable it for now */ psmouse->resync_time = 0; + /* Allow 2 invalid packets without resetting device */ + psmouse->resetafter = psmouse->pktsize * 2; + return 0; init_fail: -- 2.7.4