evdev: Only track one pending event

Instead of having a mask of pending events there is now an enum with a
single value to represent the one pending event. The event gets
flushed explicitly as part of the handling code for each event type
rather than in the outer event reading loop. The pending event is used
so that we can combine multiple motion events into one and to make
sure that we have recieved the latest position before sending a touch
up or down event. This should fix the following problems with the old
approach:

• If you release a finger and press it down again quickly you could
  get the up and down events in the same batch. However the pending
  events were always processed in the order down then up so it would
  end up notifying two down events and then an up. The pending event
  is now always flushed when there is a new up or down event so they
  will always be in the right order.

• When it got a slot event it would immediately change the slot number
  and then set the pending event. Then when it flushed the events it
  would use the new slot number to flush the old pending event so the
  events could have the wrong finger. The pending event is now
  immediately flushed when a slot event is received so it will have
  the right finger.

• If you get more than 32 events in one read then it was resetting the
  pending events before processing the next batch in
  evdev_process_events. If four fingers were pressed down at once then
  it ended up with more than 32 events and the sync message would be
  in the second batch. The pending flag for the last finger was
  getting cleared so it never got emitted. In this patch the pending
  event is no longer reset after reading nor is it explicitly flushed.
  Instead it is flushed when we receive a EV_SYN event or a different
  pending event needs to replace it.

The touchpad handling code was trying to use the pending event
mechanism to notify the relative motion events. I'm not sure why it
was doing this because it looks the event would effectively get
emitted as soon as the touchpad_process function is finished anyway
and it wasn't accumulating the values. Instead I've just changed it to
emit the event directly.

https://bugs.freedesktop.org/show_bug.cgi?id=67563

3 files changed, 129 insertions, 143 deletions

diff --git a/src/evdev-touchpad.c b/src/evdev-touchpad.c
index aa9df62c..69f913ac 100644
--- a/src/evdev-touchpad.c
+++ b/src/evdev-touchpad.c
@@ -490,10 +490,9 @@ touchpad_update_state(struct touchpad_dispatch *touchpad, uint32_t time)
 		filter_motion(touchpad, &dx, &dy, time);
 
 		if (touchpad->finger_state == TOUCHPAD_FINGERS_ONE) {
-			touchpad->device->rel.dx = wl_fixed_from_double(dx);
-			touchpad->device->rel.dy = wl_fixed_from_double(dy);
-			touchpad->device->pending_events |=
-				EVDEV_RELATIVE_MOTION | EVDEV_SYN_OR_SLOT;
+			notify_motion(touchpad->device->seat, time,
+				      wl_fixed_from_double(dx),
+				      wl_fixed_from_double(dy));
 		} else if (touchpad->finger_state == TOUCHPAD_FINGERS_TWO) {
 			if (dx != 0.0)
 				notify_axis(touchpad->device->seat,
diff --git a/src/evdev.c b/src/evdev.c
index 3ccdd3ca..c1e11d38 100644
--- a/src/evdev.c
+++ b/src/evdev.c
@@ -28,6 +28,7 @@
 #include <unistd.h>
 #include <fcntl.h>
 #include <mtdev.h>
+#include <assert.h>
 
 #include "compositor.h"
 #include "evdev.h"
@@ -64,6 +65,85 @@ evdev_led_update(struct evdev_device *device, enum weston_led leds)
 	(void)i; /* no, we really don't care about the return value */
 }
 
+static void
+transform_absolute(struct evdev_device *device, int32_t *x, int32_t *y)
+{
+       if (!device->abs.apply_calibration) {
+               *x = device->abs.x;
+               *y = device->abs.y;
+               return;
+       } else {
+               *x = device->abs.x * device->abs.calibration[0] +
+                       device->abs.y * device->abs.calibration[1] +
+                       device->abs.calibration[2];
+
+               *y = device->abs.x * device->abs.calibration[3] +
+                       device->abs.y * device->abs.calibration[4] +
+                       device->abs.calibration[5];
+       }
+}
+
+static void
+evdev_flush_pending_event(struct evdev_device *device, uint32_t time)
+{
+	struct weston_seat *master = device->seat;
+	wl_fixed_t x, y;
+	int32_t cx, cy;
+	int slot;
+
+	slot = device->mt.slot;
+
+	switch (device->pending_event) {
+	case EVDEV_NONE:
+		return;
+	case EVDEV_RELATIVE_MOTION:
+		notify_motion(master, time, device->rel.dx, device->rel.dy);
+		device->rel.dx = 0;
+		device->rel.dy = 0;
+		goto handled;
+	case EVDEV_ABSOLUTE_MT_DOWN:
+		weston_output_transform_coordinate(device->output,
+						   device->mt.slots[slot].x,
+						   device->mt.slots[slot].y,
+						   &x, &y);
+		notify_touch(master, time,
+			     slot, x, y, WL_TOUCH_DOWN);
+		goto handled;
+	case EVDEV_ABSOLUTE_MT_MOTION:
+		weston_output_transform_coordinate(device->output,
+						   device->mt.slots[slot].x,
+						   device->mt.slots[slot].y,
+						   &x, &y);
+		notify_touch(master, time,
+			     slot, x, y, WL_TOUCH_MOTION);
+		goto handled;
+	case EVDEV_ABSOLUTE_MT_UP:
+		notify_touch(master, time, slot, 0, 0,
+			     WL_TOUCH_UP);
+		goto handled;
+	case EVDEV_ABSOLUTE_MOTION:
+		transform_absolute(device, &cx, &cy);
+		weston_output_transform_coordinate(device->output,
+						   cx, cy, &x, &y);
+
+		if (device->caps & EVDEV_TOUCH) {
+			if (master->num_tp == 0)
+				notify_touch(master, time, 0,
+					     x, y, WL_TOUCH_DOWN);
+			else
+				notify_touch(master, time, 0,
+					     x, y, WL_TOUCH_MOTION);
+		} else
+			notify_motion_absolute(master, time, x, y);
+		goto handled;
+	}
+
+	assert(0 && "Unknown pending event type");
+
+handled:
+	device->pending_event = EVDEV_NONE;
+}
+
 static inline void
 evdev_process_key(struct evdev_device *device, struct input_event *e, int time)
 {
@@ -71,6 +151,8 @@ evdev_process_key(struct evdev_device *device, struct input_event *e, int time)
 	if (e->value == 2)
 		return;
 
+	evdev_flush_pending_event(device, time);
+
 	switch (e->code) {
 	case BTN_LEFT:
 	case BTN_RIGHT:
@@ -102,33 +184,40 @@ evdev_process_key(struct evdev_device *device, struct input_event *e, int time)
 }
 
 static void
-evdev_process_touch(struct evdev_device *device, struct input_event *e)
+evdev_process_touch(struct evdev_device *device,
+		    struct input_event *e,
+		    uint32_t time)
 {
 	const int screen_width = device->output->current_mode->width;
 	const int screen_height = device->output->current_mode->height;
 
 	switch (e->code) {
 	case ABS_MT_SLOT:
+		evdev_flush_pending_event(device, time);
 		device->mt.slot = e->value;
-		device->pending_events |= EVDEV_SYN_OR_SLOT;
 		break;
 	case ABS_MT_TRACKING_ID:
+		if (device->pending_event != EVDEV_NONE &&
+		    device->pending_event != EVDEV_ABSOLUTE_MT_MOTION)
+			evdev_flush_pending_event(device, time);
 		if (e->value >= 0)
-			device->pending_events |= EVDEV_ABSOLUTE_MT_DOWN;
+			device->pending_event = EVDEV_ABSOLUTE_MT_DOWN;
 		else
-			device->pending_events |= EVDEV_ABSOLUTE_MT_UP;
+			device->pending_event = EVDEV_ABSOLUTE_MT_UP;
 		break;
 	case ABS_MT_POSITION_X:
-		device->mt.x[device->mt.slot] =
+		device->mt.slots[device->mt.slot].x =
 			(e->value - device->abs.min_x) * screen_width /
 			(device->abs.max_x - device->abs.min_x);
-		device->pending_events |= EVDEV_ABSOLUTE_MT_MOTION;
+		if (device->pending_event == EVDEV_NONE)
+			device->pending_event = EVDEV_ABSOLUTE_MT_MOTION;
 		break;
 	case ABS_MT_POSITION_Y:
-		device->mt.y[device->mt.slot] =
+		device->mt.slots[device->mt.slot].y =
 			(e->value - device->abs.min_y) * screen_height /
 			(device->abs.max_y - device->abs.min_y);
-		device->pending_events |= EVDEV_ABSOLUTE_MT_MOTION;
+		if (device->pending_event == EVDEV_NONE)
+			device->pending_event = EVDEV_ABSOLUTE_MT_MOTION;
 		break;
 	}
 }
@@ -145,13 +234,15 @@ evdev_process_absolute_motion(struct evdev_device *device,
 		device->abs.x =
 			(e->value - device->abs.min_x) * screen_width /
 			(device->abs.max_x - device->abs.min_x);
-		device->pending_events |= EVDEV_ABSOLUTE_MOTION;
+		if (device->pending_event == EVDEV_NONE)
+			device->pending_event = EVDEV_ABSOLUTE_MOTION;
 		break;
 	case ABS_Y:
 		device->abs.y =
 			(e->value - device->abs.min_y) * screen_height /
 			(device->abs.max_y - device->abs.min_y);
-		device->pending_events |= EVDEV_ABSOLUTE_MOTION;
+		if (device->pending_event == EVDEV_NONE)
+			device->pending_event = EVDEV_ABSOLUTE_MOTION;
 		break;
 	}
 }
@@ -162,14 +253,19 @@ evdev_process_relative(struct evdev_device *device,
 {
 	switch (e->code) {
 	case REL_X:
+		if (device->pending_event != EVDEV_RELATIVE_MOTION)
+			evdev_flush_pending_event(device, time);
 		device->rel.dx += wl_fixed_from_int(e->value);
-		device->pending_events |= EVDEV_RELATIVE_MOTION;
+		device->pending_event = EVDEV_RELATIVE_MOTION;
 		break;
 	case REL_Y:
+		if (device->pending_event != EVDEV_RELATIVE_MOTION)
+			evdev_flush_pending_event(device, time);
 		device->rel.dy += wl_fixed_from_int(e->value);
-		device->pending_events |= EVDEV_RELATIVE_MOTION;
+		device->pending_event = EVDEV_RELATIVE_MOTION;
 		break;
 	case REL_WHEEL:
+		evdev_flush_pending_event(device, time);
 		switch (e->value) {
 		case -1:
 			/* Scroll down */
@@ -185,6 +281,7 @@ evdev_process_relative(struct evdev_device *device,
 		}
 		break;
 	case REL_HWHEEL:
+		evdev_flush_pending_event(device, time);
 		switch (e->value) {
 		case -1:
 			/* Scroll left */
@@ -203,119 +300,17 @@ evdev_process_relative(struct evdev_device *device,
 }
 
 static inline void
-evdev_process_absolute(struct evdev_device *device, struct input_event *e)
+evdev_process_absolute(struct evdev_device *device,
+		       struct input_event *e,
+		       uint32_t time)
 {
 	if (device->is_mt) {
-		evdev_process_touch(device, e);
+		evdev_process_touch(device, e, time);
 	} else {
 		evdev_process_absolute_motion(device, e);
 	}
 }
 
-static int
-is_motion_event(struct input_event *e)
-{
-	switch (e->type) {
-	case EV_REL:
-		switch (e->code) {
-		case REL_X:
-		case REL_Y:
-			return 1;
-		}
-		break;
-	case EV_ABS:
-		switch (e->code) {
-		case ABS_X:
-		case ABS_Y:
-		case ABS_MT_POSITION_X:
-		case ABS_MT_POSITION_Y:
-			return 1;
-		}
-	}
-
-	return 0;
-}
-
-static void
-transform_absolute(struct evdev_device *device, int32_t *x, int32_t *y)
-{
-       if (!device->abs.apply_calibration) {
-               *x = device->abs.x;
-               *y = device->abs.y;
-               return;
-       } else {
-               *x = device->abs.x * device->abs.calibration[0] +
-                       device->abs.y * device->abs.calibration[1] +
-                       device->abs.calibration[2];
-
-               *y = device->abs.x * device->abs.calibration[3] +
-                       device->abs.y * device->abs.calibration[4] +
-                       device->abs.calibration[5];
-       }
-}
-
-static void
-evdev_flush_motion(struct evdev_device *device, uint32_t time)
-{
-       struct weston_seat *master = device->seat;
-       wl_fixed_t x, y;
-       int32_t cx, cy;
-       int slot;
-
-       if (!(device->pending_events & EVDEV_SYN_OR_SLOT))
-		return;
-
-	slot = device->mt.slot;
-	device->pending_events &= ~EVDEV_SYN_OR_SLOT;
-	if (device->pending_events & EVDEV_RELATIVE_MOTION) {
-		notify_motion(master, time, device->rel.dx, device->rel.dy);
-		device->pending_events &= ~EVDEV_RELATIVE_MOTION;
-		device->rel.dx = 0;
-		device->rel.dy = 0;
-	}
-	if (device->pending_events & EVDEV_ABSOLUTE_MT_DOWN) {
-		weston_output_transform_coordinate(device->output,
-						   device->mt.x[slot],
-						   device->mt.y[slot],
-						   &x, &y);
-		notify_touch(master, time,
-			     device->mt.slot, x, y, WL_TOUCH_DOWN);
-		device->pending_events &= ~EVDEV_ABSOLUTE_MT_DOWN;
-		device->pending_events &= ~EVDEV_ABSOLUTE_MT_MOTION;
-	}
-	if (device->pending_events & EVDEV_ABSOLUTE_MT_MOTION) {
-		weston_output_transform_coordinate(device->output,
-						   device->mt.x[slot],
-						   device->mt.y[slot],
-						   &x, &y);
-		notify_touch(master, time,
-			     device->mt.slot, x, y, WL_TOUCH_MOTION);
-		device->pending_events &= ~EVDEV_ABSOLUTE_MT_DOWN;
-		device->pending_events &= ~EVDEV_ABSOLUTE_MT_MOTION;
-	}
-	if (device->pending_events & EVDEV_ABSOLUTE_MT_UP) {
-		notify_touch(master, time, device->mt.slot, 0, 0,
-			     WL_TOUCH_UP);
-               device->pending_events &= ~EVDEV_ABSOLUTE_MT_UP;
-       }
-       if (device->pending_events & EVDEV_ABSOLUTE_MOTION) {
-               transform_absolute(device, &cx, &cy);
-               weston_output_transform_coordinate(device->output,
-                                                  cx, cy, &x, &y);
-
-               if (device->caps & EVDEV_TOUCH) {
-                       if (master->num_tp == 0)
-				notify_touch(master, time, 0,
-					     x, y, WL_TOUCH_DOWN);
-			else
-				notify_touch(master, time, 0,
-					     x, y, WL_TOUCH_MOTION);
-		} else
-			notify_motion_absolute(master, time, x, y);
-		device->pending_events &= ~EVDEV_ABSOLUTE_MOTION;
-	}
-}
-
 static void
 fallback_process(struct evdev_dispatch *dispatch,
 		 struct evdev_device *device,
@@ -327,13 +322,13 @@ fallback_process(struct evdev_dispatch *dispatch,
 		evdev_process_relative(device, event, time);
 		break;
 	case EV_ABS:
-		evdev_process_absolute(device, event);
+		evdev_process_absolute(device, event, time);
 		break;
 	case EV_KEY:
 		evdev_process_key(device, event, time);
 		break;
 	case EV_SYN:
-		device->pending_events |= EVDEV_SYN_OR_SLOT;
+		evdev_flush_pending_event(device, time);
 		break;
 	}
 }
@@ -369,23 +364,13 @@ evdev_process_events(struct evdev_device *device,
 	struct input_event *e, *end;
 	uint32_t time = 0;
 
-	device->pending_events = 0;
-
 	e = ev;
 	end = e + count;
 	for (e = ev; e < end; e++) {
 		time = e->time.tv_sec * 1000 + e->time.tv_usec / 1000;
 
-		/* we try to minimize the amount of notifications to be
-		 * forwarded to the compositor, so we accumulate motion
-		 * events and send as a bunch */
-		if (!is_motion_event(e))
-			evdev_flush_motion(device, time);
-
 		dispatch->interface->process(dispatch, device, e, time);
 	}
-
-	evdev_flush_motion(device, time);
 }
 
 static int
@@ -601,6 +586,7 @@ evdev_device_create(struct weston_seat *seat, const char *path, int device_fd)
 	device->rel.dy = 0;
 	device->dispatch = NULL;
 	device->fd = device_fd;
+	device->pending_event = EVDEV_NONE;
 	wl_list_init(&device->link);
 
 	ioctl(device->fd, EVIOCGNAME(sizeof(devname)), devname);
diff --git a/src/evdev.h b/src/evdev.h
index 7edcce6e..6d916202 100644
--- a/src/evdev.h
+++ b/src/evdev.h
@@ -31,12 +31,12 @@
 #define MAX_SLOTS 16
 
 enum evdev_event_type {
-	EVDEV_ABSOLUTE_MOTION = (1 << 0),
-	EVDEV_ABSOLUTE_MT_DOWN = (1 << 1),
-	EVDEV_ABSOLUTE_MT_MOTION = (1 << 2),
-	EVDEV_ABSOLUTE_MT_UP = (1 << 3),
-	EVDEV_RELATIVE_MOTION = (1 << 4),
-	EVDEV_SYN_OR_SLOT = (1 << 5),
+	EVDEV_NONE,
+	EVDEV_ABSOLUTE_MOTION,
+	EVDEV_ABSOLUTE_MT_DOWN,
+	EVDEV_ABSOLUTE_MT_MOTION,
+	EVDEV_ABSOLUTE_MT_UP,
+	EVDEV_RELATIVE_MOTION,
 };
 
 enum evdev_device_capability {
@@ -66,8 +66,9 @@ struct evdev_device {
 
 	struct {
 		int slot;
-		int32_t x[MAX_SLOTS];
-		int32_t y[MAX_SLOTS];
+		struct {
+			int32_t x, y;
+		} slots[MAX_SLOTS];
 	} mt;
 	struct mtdev *mtdev;
 
@@ -75,7 +76,7 @@ struct evdev_device {
 		wl_fixed_t dx, dy;
 	} rel;
 
-	enum evdev_event_type pending_events;
+	enum evdev_event_type pending_event;
 	enum evdev_device_capability caps;
 
 	int is_mt;