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FS#55030 - [linux] regression: elantech touchpad stopped working with linux 4.12

Attached to Project: Arch Linux
Opened by Ruben Kelevra (RubenKelevra) - Friday, 04 August 2017, 08:30 GMT
Last edited by Doug Newgard (Scimmia) - Thursday, 29 March 2018, 14:12 GMT
Task Type Bug Report
Category Packages: Core
Status Assigned   Reopened
Assigned To Tobias Powalowski (tpowa)
Architecture x86_64
Severity Medium
Priority Normal
Reported Version
Due in Version Undecided
Due Date Undecided
Percent Complete 0%
Votes 1
Private No


My elantech touchpad stopped working completely with the switch to linux 4.12, which worked previously fine. The messages in DMESG didn't changed, both kernels 4.11 and 4.12 output the same log on boot:

[ 6.850968] psmouse serio1: elantech: assuming hardware version 3 (with firmware version 0x450f01)
[ 6.914945] psmouse serio1: elantech: Synaptics capabilities query result 0x68, 0x15, 0x0a.
[ 6.980838] psmouse serio1: elantech: Elan sample query result 04, 0b, 00
[ 7.325798] mousedev: PS/2 mouse device common for all mice
This task depends upon

Comment by Ruben Kelevra (RubenKelevra) - Friday, 04 August 2017, 08:33 GMT Comment by Ruben Kelevra (RubenKelevra) - Friday, 04 August 2017, 09:52 GMT
I can confirm this bug also for linux 4.12.4 which was just released to core.
Comment by loqs (loqs) - Saturday, 05 August 2017, 22:39 GMT
Please bisect the kernel and report the offending commit upstream.
You might also want to check 4.13-rc3 to see if the issue has already been fixed.
Comment by Ruben Kelevra (RubenKelevra) - Sunday, 06 August 2017, 08:05 GMT
Hey Ioqs,

thanks for the fast response! I’ve used git bisect before, a great thing to find bugs, but the Linux Kernel is too huge to be build on my machine in an finite amount of time. So if I would know how exactly bisect between a patched branch of the linux 4.11.x branch and the 4.12.x branch, it would require way over a month worth of processing time on my machine to hunt the commit down with several dozends of reboots which renders the my daily driver completely useless.

I’m fine with testing the 4.13 rc Kernel, if there’s a binary somewhere.

Best regards

Comment by loqs (loqs) - Sunday, 06 August 2017, 18:22 GMT
I am not aware of anyone producing binary packages for arch for kernel release candidate.
$ git bisect start
$ git bisect good v4.11
$ git bisect bad v4.12
Bisecting: 7831 revisions left to test after this (roughly 13 steps)
So a minimum of 13 steps assuming you could allow six hours overnight to compile then ctrl^c and repeat the next two nights that would be 18 hours of build time.
Assuming you could test on the same day building is complete and 18 hours is enough for a build if the bisect went smoothly would take thirty nice days by that schedule.
The last few iterations should build much quicker but that can be balanced out by commits that need to be skipped.
Yes reboots for each test would be necessary as this is a hardware issue I can not even suggest using a virtual machine to avoid that.
I can not really offer an alternative solution as arch does not provide a public build service and unless the bug can be proven to be an arch issue ie integration or packaging
I would expect no action to be taken on it. Please see other assigned bugs for the linux package as proof of this.
Comment by Ruben Kelevra (RubenKelevra) - Monday, 07 August 2017, 08:51 GMT
I spent yesterday compiling the 4.13 kernel, it was done after ~9 hours on my machine...

I tried the 4.13 kernel, on my machine, and the touchpad does work. The version is:


> Yes reboots for each test would be necessary as this is a hardware issue I can not even suggest using a virtual machine to avoid that.

well, sadly it's a ps/2 touchpad, not an USB one, in this case, I would had used a VM...

Comment by Ruben Kelevra (RubenKelevra) - Monday, 07 August 2017, 08:53 GMT
After 4.13rc3 works the question is more, which commit fixed it on that branch instead of, which broke it, right? I guess I should bisect in the opposite direction, then we could backport the 4.13 fix on 4.12. :)
Comment by Ruben Kelevra (RubenKelevra) - Wednesday, 09 August 2017, 11:30 GMT
Sadly 4.13rc3 isn't consistently working for me, sometimes the touchpad work, sometimes it doesn't. So the fix - whatever they tried, doesn't work that good.

I going to build the kernel on a bigger machine, I think this might work in below 1 month ;)
Comment by Ruben Kelevra (RubenKelevra) - Saturday, 02 December 2017, 11:53 GMT
This bugs has been successfuly solved upstream, please close as it 'works for me' now again. :)
Comment by loqs (loqs) - Saturday, 02 December 2017, 12:05 GMT
Glad the issue is resolved. Could you please share the version number that works for you or the commit that fixed it?
You can also use the request closure button at the top of the page to request that the issue be closed as fixed.
Comment by Ruben Kelevra (RubenKelevra) - Saturday, 02 December 2017, 21:28 GMT
Well, I cannot provide a exact version which fixed it, I was ill and just started to use my computer some days ago again. Had no trouble for a week, so I wanted to share this information here. :)
Comment by Thomas Lübking (luebking) - Saturday, 02 December 2017, 21:45 GMT
Should be

Are since those patches are in the claimed broken kernel and there're only two (obvious) patches in the relevant area of the alleged regression¹, are we sure this is fixed and not only worked around by the synaptics_intertouch parameter?

Comment by Eli Schwartz (eschwartz) - Sunday, 03 December 2017, 02:21 GMT
That commit seems to have been in the initial 4.12 release as well, so I don't think that can be the one...
Comment by Ruben Kelevra (RubenKelevra) - Thursday, 29 March 2018, 14:12 GMT
  • Field changed: Percent Complete (100% → 0%)
Well, I was obviously wrong, the bug persistent up to the latest stable kernel currently in the repos (4.15.13-1-ARCH). I think I used the wrong machine while writing the latest comment. Sorry for that.
Comment by Ruben Kelevra (RubenKelevra) - Thursday, 29 March 2018, 15:42 GMT
It's a bit messy in this ticket, so I want to do an update from my side:

The latest kernel render my touchpad completely unusable, before it was sometimes working, sometimes don't - so it was "decided" on each boot - which sounds to me like a race condition in software or hardware initialization.

Since 4.11 was the latest version, which was working fine - I gonna try all RC versions of 4.12 on which this bug starts to occour and then bisect the commit which introduce this regression.
Comment by mattia (nTia89) - Sunday, 27 February 2022, 14:01 GMT
I cannot reproduce the issue. Is it still valid?