Weston always assumes touch devices are in a touch "up" state when it starts up. However, if a touch device is in touch "down" state at Weston start-up, then touch events get out of sync in Weston (due to num_tp mismatching) and touch doesn't work. The following warnings are printed to the Weston log, dependent on whether the device has single-touch capabilities or multi-touch capabilities, respectively: touch event received with 0 points down but no surface focused touch event received with -4 points down but no surface focused 1. Place finger on touch device 2. Launch Weston 3. Release finger from touch device 4. Randomly touch the device in various locations 5. Observe clients do not respond to touch and Weston logs (above) warnings. wayland (master) heads/master-0-gcd0dccd drm (master) libdrm-2.4.50-0-g4c5de72 mesa (master) heads/master-0-gd41f539 libva (master) libva-1.2.1-0-g88ed1eb intel-driver (master) 1.2.1-0-g8f306e3 weston (master) heads/master-0-g95fdc37 efl (efl-1.8) heads/efl-1.8-0-g3801c0d elementary (elementary-1.8) heads/elementary-1.8-0-gb357bb1 wayland-fits (master) heads/master-0-gcd75d94
commit a30e29af2e4d0ad6fc476ae7cc13c4cad5119217 Author: Kristian Høgsberg <krh@bitplanet.net> Date: Wed Jan 8 22:29:20 2014 -0800 input: Ignore touch up events if num_tp is 0 This can happen if we start out with one or more fingers on the touch screen, in which case we didn't get the corresponding down event. Closes: https://bugs.freedesktop.org/show_bug.cgi?id=73367
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