On Friday 03 October 2014 11:51:22 Hans de Goede wrote:
> Hi,
>
> On 10/03/2014 11:43 AM, Pali Rohár wrote:
> > Sometimes laptops with closed lid receive invalid ALPS
> > protocol V3 packets with last bit7 set.
> >
> > This happens on Dell Latitude laptops and it looks like it
> > is BIOS bug. Probably EC does not correctly split keyboard
> > and touchpad PS/2 data and when laptop lid is closed it
> > adds 0xFF packet into touchpad PS/2 data.
> >
> > When last packet's bit7 is set it is invalid ALPS packet. So
> > Do not process it and drop it with PSMOUSE_FULL_PACKET.
> >
> > After testing it looks like this patch fixed problem with
> > reseting mouse (after series of invalid packets) when
> > laptop lid is closed on Dell Latitude machines.
> >
> > Signed-off-by: Pali Rohár <pali.rohar@xxxxxxxxx>
> > Tested-by: Pali Rohár <pali.rohar@xxxxxxxxx>
> > ---
> >
> > drivers/input/mouse/alps.c | 10 ++++++++++
> > 1 file changed, 10 insertions(+)
> >
> > diff --git a/drivers/input/mouse/alps.c
> > b/drivers/input/mouse/alps.c index 1bd5aa1..b1f44d4 100644
> > --- a/drivers/input/mouse/alps.c
> > +++ b/drivers/input/mouse/alps.c
> > @@ -1179,6 +1179,16 @@ static psmouse_ret_t
> > alps_process_byte(struct psmouse *psmouse)
> >
> > return PSMOUSE_BAD_DATA;
> >
> > }
> >
> > + if (priv->proto_version == ALPS_PROTO_V3 &&
> > psmouse->pktcnt == psmouse->pktsize) { + // For protocol
> > V3, do not process data when last packet's bit7 is set
> > + if (psmouse->packet[psmouse->pktcnt - 1] & 0x80) {
> > + psmouse_dbg(psmouse, "v3 discard packet[%i] =
%x\n",
> > + psmouse->pktcnt - 1,
> > + psmouse->packet[psmouse->pktcnt - 1]);
> > + return PSMOUSE_FULL_PACKET;
> > + }
> > + }
> > +
>
> I wonder if this should not be PSMOUSE_BAD_DATA as a return
> value ? I realize that with the 3th patch in place, that will
> cause an immediate reset, but if your theory is right that
> this ff gets inserted from the keyboard ps/2 stream, then we
> actually want a full reset as otherwise we will be out of
> sync then.
>
We really do not know what is root cause of this problem.
Probably it is BIOS/EC/firmware/... but it could be something
other too.
On my laptop - Dell Latitude E6440 - I'm getting these invalid
packets when I close LID. And they are generated too many (lot of
per second). When PSMOUSE_FULL_PACKET is returned then no driver
does not reset touchpad. With PSMOUSE_BAD_DATA psmouse decide
that it needs reset and with 3rd patch psmouse could try to reset
device too many times... So I think PSMOUSE_FULL_PACKET is better
here. And having dmesg log full of device resets is probably not
good too when laptop lid is closed.
> > /* Bytes 2 - pktsize should have 0 in the highest bit */
> > if ((priv->proto_version < ALPS_PROTO_V5) &&
> >
> > psmouse->pktcnt >= 2 && psmouse->pktcnt <=
> > psmouse->pktsize &&
>
> Regards,
>
> Hans
--
Pali Rohár
pali.rohar@xxxxxxxxx
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