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| author | Peter Hutterer <peter.hutterer@who-t.net> | 2014-03-05 13:15:20 +1000 |
|---|---|---|
| committer | Peter Hutterer <peter.hutterer@who-t.net> | 2014-03-06 14:30:03 +1000 |
| commit | 12ff51b8710aca9640caacf02a941ec8ff234348 (patch) | |
| tree | 981c4b4cdf7e8ea505eb117165b9eff2bb6f2975 /libevdev/libevdev.h | |
| parent | 68a297577aed60bb81afc5e8bcfe0e3d2e95185f (diff) | |
| download | libevdev-12ff51b8710aca9640caacf02a941ec8ff234348.tar.gz | |
Don't sync the MT state for fake MT devices
Devices with ABS_MT_SLOT-1 are fake MT devices, they merely overlap the
axis range but don't actually provide slots. The EVIOCGABS ioctl won't work to
retrieve the current value - the kernel does not store values for those axes
and the return value is always 0.
Thus, simply ignore those axes for fake MT devices and instead rely on the
next event to update the caller with the correct state for each axis.
Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Reviewed-by: Benjamin Tissoires <benjamin.tissoires@gmail.com>
Diffstat (limited to 'libevdev/libevdev.h')
| -rw-r--r-- | libevdev/libevdev.h | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/libevdev/libevdev.h b/libevdev/libevdev.h index 1855cd3..6920a76 100644 --- a/libevdev/libevdev.h +++ b/libevdev/libevdev.h @@ -377,6 +377,12 @@ extern "C" { * device is not treated as multitouch device. No slot information is * available and the ABS_MT axis range for these devices is treated as all * other EV_ABS axes. + * + * Note that because of limitations in the kernel API, such fake multitouch + * devices can not be reliably synched after a SYN_DROPPED event. libevdev + * ignores all ABS_MT axis values during the sync process and instead + * relies on the device to send the current axis value with the first event + * after SYN_DROPPED. */ /** |