Bug 101670

Summary: Pressure sensitivity calibrated value for ALPS touchpad on Dell Latitude E6220
Product: Wayland Reporter: Chris Koresko <ckoresko>
Component: libinputAssignee: Wayland bug list <wayland-bugs>
Status: RESOLVED FIXED QA Contact:
Severity: normal    
Priority: medium CC: peter.hutterer
Version: unspecified   
Hardware: x86-64 (AMD64)   
OS: Linux (All)   
Whiteboard:
i915 platform: i915 features:

Description Chris Koresko 2017-07-01 18:53:55 UTC 
After testing with libinput 1.7.3 (from Fedora 26 beta) on Fedora 25, I have determined the following touch pressure values to work well with the ALPS touchpad on the Latitude E6220.

The contents of /etc/udev/hwdb.d/71-touchpad-local.hwdb are:
  libinput:name:*AlpsPS/2 ALPS GlidePoint:dmi:*
   LIBINPUT_ATTR_PRESSURE_RANGE=103:100

Without this entry in /etc/udev/hwdb.d/71-touchpad-local.hwdb the touchpad is almost unusable due to excessive sensitivity (it responds with mouse movements even when the finger is held above the surface, so the mouse moves as the finger approaches and departs the sruface).  With this setting the behavior is as expected.

The dimensions of the exposed surface of this touchpad are approximately 80x40 mm.

The output from udevadm info --query=all is:

  /dev/input/event5
  P: /devices/platform/i8042/serio1/input/input6/event5
  N: input/event5
  E: DEVNAME=/dev/input/event5
  E: DEVPATH=/devices/platform/i8042/serio1/input/input6/event5
  E: ID_BUS=i8042
  E: ID_INPUT=1
  E: ID_INPUT_TOUCHPAD=1
  E: ID_INPUT_TOUCHPAD_INTEGRATION=internal
  E: LIBINPUT_ATTR_PRESSURE_RANGE=103:100
  E: LIBINPUT_DEVICE_GROUP=11/2/8/300:isa0060/serio1
  E: LIBINPUT_MODEL_ALPS_TOUCHPAD=1
  E: LIBINPUT_MODEL_FIRMWARE_VERSION=300
  E: MAJOR=13
  E: MINOR=69
  E: SUBSYSTEM=input
  E: USEC_INITIALIZED=4392877
Comment 1 Peter Hutterer 2017-07-03 06:02:38 UTC 
wow, that is a high threshold. I'll need the /sys/class/dmi/id/modalias please, your current dmi match would apply to all ALPS touchpads, I don't think that's something we want here :)
Comment 2 Chris Koresko 2017-07-03 12:18:42 UTC 
Sorry, forgot to include the DMI info.  Here it is:

cat /sys/class/dmi/id/modalias

dmi:bvnDellInc.:bvrA14:bd05/12/2017:svnDellInc.:pnLatitudeE6220:pvr01:rvnDellInc.:rn0R97MN:rvrA00:cvnDellInc.:ct9:cvr:
Comment 3 Peter Hutterer 2017-07-04 03:12:10 UTC 
commit 7c983d6088fe5098f3236b1400d98dbbf92712df (HEAD -> master, tmp-today/master, origin/master, github/master)
Author: Peter Hutterer <peter.hutterer@who-t.net>
Date:   Tue Jul 4 12:39:09 2017 +1000

    udev: add custom pressure range for Dell Latitude E6620
Comment 4 Chris Koresko 2017-07-04 03:59:49 UTC 
E6220, please.
Comment 5 Peter Hutterer 2017-07-04 04:03:51 UTC 
oh, whoops. typoed that one. the patch itself is correct, just the commit message is wrong, sorry about that.
Comment 6 Chris Koresko 2017-08-20 19:55:38 UTC 
After some more experimentation I have found that a better pressure range is 

LIBINPUT_ATTR_PRESSURE_RANGE=100:90

This gives some more sensitivity to the fingers without introducing spurious touches and movements.
Comment 7 Peter Hutterer 2017-08-21 01:59:32 UTC 
rightyo, updated to 100:90 and pushed as 64fcd7bd024124acdaa3dd1e544775dc906f7c45. Thanks

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