-
It is possible for a click to get reported before any related touch events get reported, here is the relevant part of an evemu-record session on a T440s: E: 3.985585 0000 0000 0000 # ------------ SYN_REPORT (0) ---------- E: 3.997419 0003 0039 -001 # EV_ABS / ABS_MT_TRACKING_ID -1 E: 3.997419 0001 014a 0000 # EV_KEY / BTN_TOUCH 0 E: 3.997419 0003 0018 0000 # EV_ABS / ABS_PRESSURE 0 E: 3.997419 0001 0145 0000 # EV_KEY / BTN_TOOL_FINGER 0 E: 3.997419 0000 0000 0000 # ------------ SYN_REPORT (0) ---------- E: 5.117881 0001 0110 0001 # EV_KEY / BTN_LEFT 1 E: 5.117881 0000 0000 0000 # ------------ SYN_REPORT (0) ---------- E: 5.133422 0003 0039 0187 # EV_ABS / ABS_MT_TRACKING_ID 187 E: 5.133422 0003 0035 3098 # EV_ABS / ABS_MT_POSITION_X 3098 E: 5.133422 0003 0036 3282 # EV_ABS / ABS_MT_POSITION_Y 3282 E: 5.133422 0003 003a 0046 # EV_ABS / ABS_MT_PRESSURE 46 E: 5.133422 0001 014a 0001 # EV_KEY / BTN_TOUCH 1 E: 5.133422 0003 0000 3102 # EV_ABS / ABS_X 3102 E: 5.133422 0003 0001 3282 # EV_ABS / ABS_Y 3282 E: 5.133422 0003 0018 0046 # EV_ABS / ABS_PRESSURE 46 E: 5.133422 0001 0145 0001 # EV_KEY / BTN_TOOL_FINGER 1 E: 5.133422 0000 0000 0000 # ------------ SYN_REPORT (0) ---------- Notice the BTN_LEFT event all by itself! If this happens, it may lead to the following problem scenario: -touch the touchpad in its right click area -let go of the touchpad -rapidly click in the middle area, so that BTN_LEFT gets reported before the new coordinates (such as seen in the trace above, this may require some practicing with evemu-record to reproduce) -the driver registers the click as a right click because it uses the old coordinates from the cumulative coordinates to determine the click location This commit fixes this by: 1) Resetting the cumulative coordinates not only when no button is pressed, but also when there is no finger touching the touchpad, so that when we do get a touch the cumulative coordinates start at the right place 2) Delaying processing the BTN_LEFT down transition if there is no finger touching the touchpad This approach has one downside, if we wrongly identify a touchpad as a clickpad, then the left button won't work unless the user touches the touchpad while clicking the left button. If we want we can fix this by doing something like this: 1) Making update_hw_button_state return a delay; and 2) Tracking that we've delayed BTN_LEFT down transition processing; and 3) When we've delayed BTN_LEFT down transition return a small delay value; and 4) If when we're called again we still don't have a finger down, just treat the click as a BTN_LEFT But this is not worth the trouble IMHO, the proper thing to do in this scenario is to fix the mis-identification of the touchpad as a clickpad. Signed-off-by:
Hans de Goede <hdegoede@redhat.com> Signed-off-by:
Peter Hutterer <peter.hutterer@who-t.net>
bbe4c56c
