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    SubjectRe: [PATCH v3 2/4] input: alps: Allow 2 invalid packets without resetting device
    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
    >

    --
    Dmitry
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