[PATCH libinput] fallback: send key events out immediately upon receiving them

[Peter Hutterer]

On Mon, Dec 11, 2017 at 02:39:01PM +0000, Eric Engestrom wrote:
> On Friday, 2017-12-08 10:17:17 +1000, Peter Hutterer wrote:
> > Commit db3b6fe5f7f8 "fallback: change to handle the state at EV_SYN time"
> > introduced regressions for two types of event sequences.
> > 
> > One is a kernel bug - some devices/drivers like the asus-wireless send a key
> > press + release within the same event frame which now cancels out and
> > disappears into the ether. This should be fixed in the kernel drivers but
> > there appear to be enough of them that we can't just pretend it's an outlier.
> > 
> > The second issue is a libinput bug. If we get two key events in the same frame
> > (e.g. shift + A) we update the state correctly but the events are sent in the
> > order of the event codes. KEY_A sorts before KEY_LEFTSHIFT and our shift + A
> > becomes A + shift.
> > 
> > Fix this by treating key events as before db3b6fe5f7f8 - by sending them out
> > as we get them.
> > 
> > https://bugs.freedesktop.org/show_bug.cgi?id=104030
> > 
> > Signed-off-by: Peter Hutterer <peter.hutterer at who-t.net>
> > ---
> >  src/evdev-fallback.c | 35 ++++++++++++++++----------------
> >  test/test-keyboard.c | 56 ++++++++++++++++++++++++++++++++++++++++++++++++++++
> >  2 files changed, 73 insertions(+), 18 deletions(-)
> > 
> > diff --git a/src/evdev-fallback.c b/src/evdev-fallback.c
> > index 52a3bde1..0cd2497e 100644
> > --- a/src/evdev-fallback.c
> > +++ b/src/evdev-fallback.c
> > @@ -501,6 +501,22 @@ fallback_process_key(struct fallback_dispatch *dispatch,
> >  	}
> >  
> >  	hw_set_key_down(dispatch, e->code, e->value);
> > +
> > +	switch (type) {
> > +	case KEY_TYPE_NONE:
> > +		break;
> > +	case KEY_TYPE_KEY:
> > +		fallback_keyboard_notify_key(
> > +			     dispatch,
> > +			     device,
> > +			     time,
> > +			     e->code,
> > +			     e->value ? LIBINPUT_KEY_STATE_PRESSED :
> > +					LIBINPUT_KEY_STATE_RELEASED);
> > +		break;
> > +	case KEY_TYPE_BUTTON:
> > +		break;
> > +	}
> >  }
> >  
> >  static void
> > @@ -834,27 +850,10 @@ fallback_handle_state(struct fallback_dispatch *dispatch,
> >  	if (dispatch->pending_event & EVDEV_KEY) {
> >  		bool want_debounce = false;
> >  		for (unsigned int code = 0; code <= KEY_MAX; code++) {
> > -			bool new_state;
> > -
> >  			if (!hw_key_has_changed(dispatch, code))
> >  				continue;
> >  
> > -			new_state = hw_is_key_down(dispatch, code);
> > -
> > -			switch (get_key_type(code)) {
> > -			case KEY_TYPE_NONE:
> > -				break;
> > -			case KEY_TYPE_KEY:
> > -				fallback_keyboard_notify_key(
> > -						     dispatch,
> > -						     device,
> > -						     time,
> > -						     code,
> > -						     new_state ?
> > -							     LIBINPUT_KEY_STATE_PRESSED :
> > -							     LIBINPUT_KEY_STATE_RELEASED);
> > -				break;
> > -			case KEY_TYPE_BUTTON:
> > +			if (get_key_type(code) == KEY_TYPE_BUTTON) {
> >  				want_debounce = true;
> >  				break;
> 
> This will break out of the `for()` now :)

yep, good catch. that's intentional though. Previously, the loop did two
things: send out key events and check for want_debounce.  Now it doesn't
send key events anymore so as soon as we know that we want to debounce, we
can exit the loop.

Cheers,
   Peter

> 
> >  			}
> > diff --git a/test/test-keyboard.c b/test/test-keyboard.c
> > index dc2e630e..db836381 100644
> > --- a/test/test-keyboard.c
> > +++ b/test/test-keyboard.c
> > @@ -365,6 +365,61 @@ START_TEST(keyboard_no_buttons)
> >  }
> >  END_TEST
> >  
> > +START_TEST(keyboard_frame_order)
> > +{
> > +	struct litest_device *dev = litest_current_device();
> > +	struct libinput *li = dev->libinput;
> > +
> > +	if (!libevdev_has_event_code(dev->evdev, EV_KEY, KEY_A) ||
> > +	    !libevdev_has_event_code(dev->evdev, EV_KEY, KEY_LEFTSHIFT))
> > +		return;
> > +
> > +	litest_drain_events(li);
> > +
> > +	litest_event(dev, EV_KEY, KEY_LEFTSHIFT, 1);
> > +	litest_event(dev, EV_KEY, KEY_A, 1);
> > +	litest_event(dev, EV_SYN, SYN_REPORT, 0);
> > +	libinput_dispatch(li);
> > +
> > +	litest_assert_key_event(li,
> > +				KEY_LEFTSHIFT,
> > +				LIBINPUT_KEY_STATE_PRESSED);
> > +	litest_assert_key_event(li, KEY_A, LIBINPUT_KEY_STATE_PRESSED);
> > +
> > +	litest_event(dev, EV_KEY, KEY_LEFTSHIFT, 0);
> > +	litest_event(dev, EV_KEY, KEY_A, 0);
> > +	litest_event(dev, EV_SYN, SYN_REPORT, 0);
> > +	libinput_dispatch(li);
> > +
> > +	litest_assert_key_event(li,
> > +				KEY_LEFTSHIFT,
> > +				LIBINPUT_KEY_STATE_RELEASED);
> > +	litest_assert_key_event(li, KEY_A, LIBINPUT_KEY_STATE_RELEASED);
> > +
> > +	litest_event(dev, EV_KEY, KEY_A, 1);
> > +	litest_event(dev, EV_KEY, KEY_LEFTSHIFT, 1);
> > +	litest_event(dev, EV_SYN, SYN_REPORT, 0);
> > +	libinput_dispatch(li);
> > +
> > +	litest_assert_key_event(li, KEY_A, LIBINPUT_KEY_STATE_PRESSED);
> > +	litest_assert_key_event(li,
> > +				KEY_LEFTSHIFT,
> > +				LIBINPUT_KEY_STATE_PRESSED);
> > +
> > +	litest_event(dev, EV_KEY, KEY_A, 0);
> > +	litest_event(dev, EV_KEY, KEY_LEFTSHIFT, 0);
> > +	litest_event(dev, EV_SYN, SYN_REPORT, 0);
> > +	libinput_dispatch(li);
> > +
> > +	litest_assert_key_event(li, KEY_A, LIBINPUT_KEY_STATE_RELEASED);
> > +	litest_assert_key_event(li,
> > +				KEY_LEFTSHIFT,
> > +				LIBINPUT_KEY_STATE_RELEASED);
> > +
> > +	libinput_dispatch(li);
> > +}
> > +END_TEST
> > +
> >  START_TEST(keyboard_leds)
> >  {
> >  	struct litest_device *dev = litest_current_device();
> > @@ -432,6 +487,7 @@ litest_setup_tests_keyboard(void)
> >  	litest_add("keyboard:time", keyboard_time_usec, LITEST_KEYS, LITEST_ANY);
> >  
> >  	litest_add("keyboard:events", keyboard_no_buttons, LITEST_KEYS, LITEST_ANY);
> > +	litest_add("keyboard:events", keyboard_frame_order, LITEST_KEYS, LITEST_ANY);
> >  
> >  	litest_add("keyboard:leds", keyboard_leds, LITEST_ANY, LITEST_ANY);
> >  
> > -- 
> > 2.13.6
> >