On Sat, 2018-06-02 at 14:14 +1000, Peter Hutterer wrote:
On 1/6/18 22:50 , Timur Kristóf wrote:
On Thu, 2018-05-31 at 13:44 -0700, Laura Abbott wrote:
On 05/24/2018 04:13 PM, Timur Kristóf wrote:
Hi,
On the XPS 13 9360 and 9370 xinput sees two touchpads instead of one: ⎡ Virtual core pointer id=2 [master pointer (3)] ⎜ ↳ Virtual core XTEST pointer id=4 [slave pointer (2)] ⎜ ↳ DELL07E6:00 06CB:76AF Touchpad id=12 [slave pointer (2)] ⎜ ↳ SynPS/2 Synaptics TouchPad id=17 [slave pointer (2)]
dmesg also gives me the following:
[ 1.429811] psmouse serio1: synaptics: Your touchpad (PNP: DLL07e6 PNP0f13) says it can support a different bus. If i2c-hid and hid- rmi are not used, you might want to try setting psmouse.synaptics_intertouch to 1 and report this to linux-input@vger.kernel.org.
The Dell one is the real touchpad, the other one is an artifact of the psmouse driver. Weird touchpad freezes and jittering issues can be observed when both of these devices are there. The general advice on the web is to blacklist the psmouse driver. (This is also published by Dell as a .deb package which contains a config file doing just this.)
However, on Fedora I cannot blacklist the psmouse driver because it is compiled built-in instead of as a module. Could you guys change the Fedora kernel config to compile it as a module instead?
Thanks & best regards, Timur
So assuming nobody else has objections, I think it's okay to at least try this on rawhide and see if it uncovers any other problems.
Thanks, Laura
Looking into this a bit more, the root cause of this issue is that the touchpad is wired up in such a way that it is accessible on both PS/2 and I2C. I2C is preferred and used by i2c-hid but at the same time the PS/2 interface is also picked up by psmouse. Thus, Xorg sees the two interfaces as two different devices.
That is fairly standard and doesn't matter. This was also the case for earlier SMBus implementation but the common thing was that the PS/2 device never actually sent events. So it was only an issue for some tools that expected only one touchpad to exist (e.g. synclient). Check with evemu-record whether the device sends events. if not, then Xorg is definitely not confused by it. If it does and both event nodes send events then yes, we have a kernel bug there.
I've talked to Mario, a developer at Dell, and he pointed me to this freedesktop bug report: https://bugs.freedesktop.org/show_bug.cgi?id=101470
According to his description, there is actually no input coming from PS/2 but it is still (wrongly) picked up by syndaemon. To be honest, I'm not sure if Fedora uses syndaemon (I assume libinput is used for everything now?), but I can tell that the touchpad does jitter when the PS/2 device is there.
I can also confirm that evemu-record doesn't see any input coming from the PS/2 device.
Solution would be to somehow remove the psmouse-detected device node from the system when i2c-hid detects the same device. Is this possible?
This is more an upstream discussion, CC-ing benjamin for details.
I do recommend filing a bug with an evemu recording of a freezing/jittering interaction. Lots of touchpad processing happens in userspace and this could be the cause of pressure thresholds set too high. CC me on that bug and I can have a look. sudo libinput debug-events --verbose will also show extra information including things when a touch ended based on its pressure information.
I can try to reproduce the problem and see if I can make an evemu recording. What should I file the bug against (and where)? Unfortunately I'm not familiar with the components involved.
Searching for libinput in the journal reveals a bunch of touch jump messages, which seem to be related to the problem: https://paste.fedoraproject.org/paste/MoZGqf25VpHjCLSYzTxdfw
Best regards, Tim