Re: [PATCH v2 2/3] input: alps: For protocol V3, do not process data when last packet's bit7 is set

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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.

-- 
Dmitry
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