linux-kernel - Re: [git pull] Input updates for 3.18-rc4

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Message-ID: <20141127204139.GA18953@lantern>
Date:	Thu, 27 Nov 2014 21:41:39 +0100
From:	ulrik.debie-os@...ig.org
To:	Benjamin Tissoires <benjamin.tissoires@...il.com>
Cc:	Marcus Overhagen <marcus.overhagen@...il.com>,
	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	Hans de Goede <hdegoede@...hat.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	linux-input <linux-input@...r.kernel.org>,
	Jiri Kosina <jkosina@...e.cz>
Subject: Re: [git pull] Input updates for 3.18-rc4

Hi Benjamin,

On Wed, Nov 26, 2014 at 09:33:26AM -0500, Benjamin Tissoires wrote:
> 
> Hi Ulrik,
> 
> On Tue, Nov 25, 2014 at 4:23 PM,  <ulrik.debie-os@...ig.org> wrote:
> > Hi,
> >
> > On Wed, Nov 19, 2014 at 11:21:31PM +0100, Marcus Overhagen wrote:
> >> Hi,
> >>
> >> when moving a single finger [3] seems to be one of 0x21, 0x25, 0x31, 0x35
> >> moving two fingers [3] seems to be mostly 0x22, 0x26, 0x32, 0x36  but
> >> also sometimes it's 0x42, 0x46, 0x52, 0x56.
> >> It seems to occationally seems to switch between these two groups
> >> after touching the pad with three or more fingers, but not every time.
> >>
> >> Moving three fingers I see[3] beeing  0x26, 0x36, 0x76, 0x66 (probably more)
> >>
> >> regards
> >> Marcus
> >
> >
> > Ok, after some digging through the packet dump kindly provided by Marcus,
> > it is clear that Documentation/input/elantech.txt is not correctly
> > representing anymore the packets of the v4 hardware. There should be some
> > 0 and 1's replaced by x because they are currently "don't know" and definitely
> > not always 0 or 1.
> >
> > Example:
> > He has 0x26,0x36,0x46,0x56,0x66,0x76 in packet[3], and the documentation had
> > the bits as:
> > id2 id1 id0   1   0   0   1   0
> >               X       X
> > The bits marked with X can thus be different. But when those are changed to
> > X==don't care then it is not trivial to differentiate them from the trackpoint
> > that has the following signature for that byte:
> > 0   0   ~sy  ~sx  0   1   1   0
> >
> >
> >
> > I'm considering the following change:
> > The test
> >
> >         t = get_unaligned_le32(&packet[0]);
> >
> >         switch (t & ~7U) {
> >         case 0x06000030U:
> >         case 0x16008020U:
> >         case 0x26800010U:
> >         case 0x36808000U:
> >
> > could be moved to elantech_packet_check_v3/4() instead of the
> > simpler test on the lowest nibble of packet[3] (and keep the etd->tp_dev check):
> >        if ((packet[3] & 0x0f) == 0x06 && etd->tp_dev)
> >                 return PACKET_TRACKPOINT;
> >
> > I'll think a little bit more on it. Based on the packet dump I have this
> > seems to allow a perfect discrimation between trackpoint and touchpad packets.
> >
> 
> Thanks for the progress on these. Do you think you will be able to get
> something in shape before the final 3.18?
> 
> Dmitry, can we either revert the current patches and reschedule them
> for 3.19 or at least apply one quick fix? I am starting to see a lot
> of people complaining about it, and I am wondering if adding this
> functionality in a -rc5 release was not a good idea :-/.

Dmitry has already requested Linus to pull the quick fix 
b54783f2de0c216115333eca1a8d3d5c3e75b 

I expect this fix from Dmitry to also help the person that you reported,
could you confirm that ? Basically when the hardware reports no trackpoint
present, it will then behave like before the trackpoint as enabled on v4.

I expect some responses from people soon in order to find out if there
is even a better way to fix it.

Thanks,
Kind regards,
Ulrik



> Cheers,
> Benjamin
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