[v3,2/4] input: alps: Allow 2 invalid packets without resetting device
diff mbox

Message ID 1414884310-19842-3-git-send-email-pali.rohar@gmail.com
State New, archived
Headers show

Commit Message

Pali Rohár Nov. 1, 2014, 11:25 p.m. UTC
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 <pali.rohar@gmail.com>
Tested-by: Pali Rohár <pali.rohar@gmail.com>
Cc: stable@vger.kernel.org
---
 drivers/input/mouse/alps.c |    3 +++
 1 file changed, 3 insertions(+)

Comments

Dmitry Torokhov Nov. 8, 2014, 9 p.m. UTC | #1
On Sun, Nov 02, 2014 at 12:25:08AM +0100, Pali Rohár wrote:
> 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 <pali.rohar@gmail.com>
> Tested-by: Pali Rohár <pali.rohar@gmail.com>
> Cc: stable@vger.kernel.org

Applied, thank you.

> ---
>  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 a772745..7c47e97 100644
> --- a/drivers/input/mouse/alps.c
> +++ b/drivers/input/mouse/alps.c
> @@ -2391,6 +2391,9 @@ 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:
> -- 
> 1.7.9.5
>

Patch
diff mbox

diff --git a/drivers/input/mouse/alps.c b/drivers/input/mouse/alps.c
index a772745..7c47e97 100644
--- a/drivers/input/mouse/alps.c
+++ b/drivers/input/mouse/alps.c
@@ -2391,6 +2391,9 @@  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: