This looks like a libinput bug (well, it does say "libinput bug" on the package) but it hasn't been that for a long time. The cause is almost always insufficient motivation to call libinput_dispatch() by the caller, or at least not doing it with the celerity libinput demands (and deserves, if I may say so).
Up-, down- or side-grade it to a client bug, so the outrage can be directed elsewhere, preferably away from me. And add a section to the documentation, just in case someone actually reads this stuff. Signed-off-by: Peter Hutterer <peter.hutte...@who-t.net> --- doc/faqs.dox | 22 ++++++++++++++++++++++ src/timer.c | 8 ++++---- 2 files changed, 26 insertions(+), 4 deletions(-) diff --git a/doc/faqs.dox b/doc/faqs.dox index f0d85859..d5190926 100644 --- a/doc/faqs.dox +++ b/doc/faqs.dox @@ -198,4 +198,26 @@ href="https://www.freedesktop.org/software/systemd/man/hwdb.html";>udev hwdb</a> or patches that include a change to the hwdb. See @ref hwdb for details on the hwdb and how to modify it locally. +@section faq_timer_offset What causes the "timer offset negative" warning? + +libinput relies on the caller to call libinput_dispatch() whenever data is +available on the epoll-fd. Doing so will process the state of all devices +and can trigger some timers to be set (e.g. palm detection, tap-to-click, +disable-while-typing, etc.). Internally, libinput's time offsets are always +based on the event time of the triggering event. + +For example, a touch event with time T may trigger a timer for the time T + +180ms. When setting a timer, libinput checks the wall clock time to ensure +that this time T + offset is still in the future. If not, the warning is +logged. + +When this warning appears, it simply means that too much time has passed +between the event occuring (and the epoll-fd triggering) and the current +time. In almost all cases this is an indication of the caller being +overloaded and not handling events as speedily as required. + +The warning has no immediate effect on libinput's behavior but some of the +functionality that relies on the timer may be impeded (e.g. palms are not +detected as they should be). + */ diff --git a/src/timer.c b/src/timer.c index f8de6662..584673a0 100644 --- a/src/timer.c +++ b/src/timer.c @@ -86,10 +86,10 @@ libinput_timer_set_flags(struct libinput_timer *timer, uint64_t now = libinput_now(timer->libinput); if (expire < now) { if ((flags & TIMER_FLAG_ALLOW_NEGATIVE) == 0) - log_bug_libinput(timer->libinput, - "timer %s: offset negative (-%dms)\n", - timer->timer_name, - us2ms(now - expire)); + log_bug_client(timer->libinput, + "timer %s: offset negative (-%dms)\n", + timer->timer_name, + us2ms(now - expire)); } else if ((expire - now) > ms2us(5000)) { log_bug_libinput(timer->libinput, "timer %s: offset more than 5s, now %d expire %d\n", -- 2.14.3 _______________________________________________ wayland-devel mailing list wayland-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/wayland-devel
