Re: Thinkpad E420s (E220s and X220) trackpoint detection

On 06.11.2012 20:31, Casey Harkins wrote:

I am still experiencing the trackpoint detection issue raised in
kernel.org bug #33292:

https://bugzilla.kernel.org/show_bug.cgi?id=33292

The bug was closed as OBSOLETE, with a request to re-open and post a
summary to this list if anyone is still experiencing the bug. While a
few people have responded that they are still experiencing the bug, I
was unable to locate any summary posted to this list as requested.

On at least these three Thinkpad models (E420s, E220s and X220), the
trackpoint (and the physical mouse buttons) operate as a passthrough
device through the Synaptics touchpad. On boot or waking from sleep,
the trackpoint device frequently is not detected, rendering the
trackpoint (and physical buttons) useless. Based on previous
discussions on this list, it appears that this is accompanied by a
failure to get a proper id (PSMOUSE_CMD_GETID):

http://www.spinics.net/lists/linux-input/msg14846.html

At a seemingly random interval, the touchpad will freeze for a few
seconds, then both the touchpad and trackpoint become usable. When
this occurs, it is accompanied by a "lost synchronization" message
from the synaptics driver. Moving the trackpoint repeatedly sometimes
appears to shorten this random interval.

On the X220, the bios allows for the touchpad to be disabled, which
apparently causes the trackpoint to be consistently detected. The
E420s and E220s do not have this bios option. Specifying
psmouse.proto=bare will also consistently allow the trackpoint to be
detected, but disables any advanced touchpad features (such as two
finger scrolling).

In addition to the kernel.org bug report, this issue was reported as
launchpad bug #787738:

https://bugs.launchpad.net/ubuntu/+source/linux/+bug/787738

The issue has also been discussed in at least two threads on this 
list:

X220: http://www.spinics.net/lists/linux-input/msg14828.html
E220s: http://www.spinics.net/lists/linux-input/msg17550.html

What is needed to try and track the cause down and either fix the bug
(if the problem is on the kernel side), or work-around the issue if 
it
is a hardware issue (can we force the resynchronization)?

I'm having this exact same issue on a Lenovo L430 but logged it against 
bug #48161[1] thinking it was something to do with the elantech 
touchpad. Now that I've read this bug #33292 it looks like I logged my 
data against the wrong bug.

This is also the issue my recent message[2] to the mailing list was 
about. I'm happy to test and debug but it's way beyond my kernel hacking 
skills to provide a patch.

1: https://bugzilla.kernel.org/show_bug.cgi?id=48161
2: http://www.spinics.net/lists/linux-input/msg23374.html

Thanks,

-casey
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