evdev: fix input lag when processing input from output repaint
When the compositor is in a repaint cycle, input is processed only once per frame. However, a call to evdev_input_device_data() would handle at most 8 events at time. When there was more than 8 events pending for a given frame, input lag would occur. This was most visible with multi touch input. This patch changes the evdev_input_device_data() so that it will handle all the events available in the fd. In order to do that, the fd is put in non-blocking mode, so that it is possible to loop on read and stop on EAGAIN instead of blocking.
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parent
afee221ccb
commit
29d955685f
63
src/evdev.c
63
src/evdev.c
@ -322,35 +322,18 @@ evdev_flush_motion(struct evdev_input_device *device, uint32_t time)
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device->type &= ~EVDEV_ABSOLUTE_MOTION;
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}
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}
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#define NUM_EVENTS 8
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static int
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evdev_input_device_data(int fd, uint32_t mask, void *data)
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static void
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evdev_process_events(struct evdev_input_device *device,
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struct input_event *ev, int count)
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{
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struct weston_compositor *ec;
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struct evdev_input_device *device = data;
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struct input_event ev[NUM_EVENTS], *e, *end;
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int len;
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struct input_event *e, *end;
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uint32_t time = 0;
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ec = device->master->base.compositor;
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if (!ec->focus)
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return 1;
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if (device->mtdev)
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len = mtdev_get(device->mtdev, fd, ev, NUM_EVENTS) *
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sizeof (struct input_event);
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else
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len = read(fd, &ev, sizeof ev);
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if (len < 0 || len % sizeof e[0] != 0) {
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/* FIXME: call device_removed when errno is ENODEV. */;
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return 1;
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}
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device->type = 0;
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e = ev;
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end = (void *) ev + len;
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end = e + count;
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for (e = ev; e < end; e++) {
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time = e->time.tv_sec * 1000 + e->time.tv_usec / 1000;
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@ -373,10 +356,42 @@ evdev_input_device_data(int fd, uint32_t mask, void *data)
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}
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evdev_flush_motion(device, time);
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}
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static int
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evdev_input_device_data(int fd, uint32_t mask, void *data)
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{
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struct weston_compositor *ec;
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struct evdev_input_device *device = data;
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struct input_event ev[32];
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int len;
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ec = device->master->base.compositor;
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if (!ec->focus)
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return 1;
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/* If the compositor is repainting, this function is called only once
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* per frame and we have to process all the events available on the
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* fd, otherwise there will be input lag. */
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do {
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if (device->mtdev)
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len = mtdev_get(device->mtdev, fd, ev,
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ARRAY_LENGTH(ev)) *
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sizeof (struct input_event);
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else
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len = read(fd, &ev, sizeof ev);
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if (len < 0 || len % sizeof ev[0] != 0) {
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/* FIXME: call device_removed when errno is ENODEV. */
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return 1;
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}
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evdev_process_events(device, ev, len / sizeof ev[0]);
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} while (len > 0);
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return 1;
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}
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/* copied from udev/extras/input_id/input_id.c */
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/* we must use this kernel-compatible implementation */
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@ -463,7 +478,9 @@ evdev_input_device_create(struct evdev_input *master,
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device->rel.dx = 0;
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device->rel.dy = 0;
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/* if O_NONBLOCK is not set, mtdev_get() blocks */
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/* Use non-blocking mode so that we can loop on read on
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* evdev_input_device_data() until all events on the fd are
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* read. mtdev_get() also expects this. */
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device->fd = open(path, O_RDONLY | O_NONBLOCK);
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if (device->fd < 0)
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goto err0;
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