On Wednesday 15 October 2014 20:17:40 Dmitry Torokhov wrote:
> On Wed, Oct 15, 2014 at 08:06:45PM +0200, Pali Rohár wrote:
> > On Wednesday 15 October 2014 19:55:24 Dmitry Torokhov wrote:
> > > Hi Pali,
> > >
> > > On Fri, Oct 03, 2014 at 03:51:12PM +0200, 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.
> > >
> > > Is it always 0xff or do you see different values with the
> > > 7th bit set? Also, the "bad data" - does is always stop
> > > on the 6th byte of the data stream or the "real" 6th byte
> > > comes after the bad one?
> > >
> > > Thanks.
> >
> > In this case stream is:
> >
> > 0 1 2 3 4 5 0 1 2 3 4 5 0 1 2 3 4 5 ...
> > V V V V V X V V V V V X V V V V V X ...
> >
> > number packet position in buffer, V means that packet at
> > specified position in buffer is valid (and also all previous
> > packets in buffer are valid), X means packet at position is
> > invalid.
> >
> > It means that alps driver receive 5 valid packets and after
> > that one is invalid. And again it receive 5 valid and last
> > invalid...
> >
> > I looked into my logs and X was always 0xFF.
>
> OK, then I think we should change the test to explicitly look
> for 0xff when returning PSMOUSE_PACKET_FULL.
>
> Thanks.
Tommy, this patch was originally written by you. (here is)
+ 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;
+ }
+ }
+
Should be condition packet[last] & 0x80 or should be == 0xFF?
--
Pali Rohár
pali.rohar@xxxxxxxxx
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