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evdev: fix input lag when processing input from output repaint

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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.
This commit is contained in:
Ander Conselvan de Oliveira 2012-03-20 19:52:57 -04:00 committed by Kristian Høgsberg
parent afee221ccb
commit 29d955685f
1 changed files with 41 additions and 24 deletions
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65
src/evdev.c
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@ -322,35 +322,18 @@ evdev_flush_motion(struct evdev_input_device *device, uint32_t time)
device->type &= ~EVDEV_ABSOLUTE_MOTION;
}
}
#define NUM_EVENTS 8
static int
evdev_input_device_data(int fd, uint32_t mask, void *data)
static void
evdev_process_events(struct evdev_input_device *device,
struct input_event *ev, int count)
{
struct weston_compositor *ec;
struct evdev_input_device *device = data;
struct input_event ev[NUM_EVENTS], *e, *end;
int len;
struct input_event *e, *end;
uint32_t time = 0;
ec = device->master->base.compositor;
if (!ec->focus)
return 1;
if (device->mtdev)
len = mtdev_get(device->mtdev, fd, ev, NUM_EVENTS) *
sizeof (struct input_event);
else
len = read(fd, &ev, sizeof ev);
if (len < 0 || len % sizeof e[0] != 0) {
/* FIXME: call device_removed when errno is ENODEV. */;
return 1;
}
device->type = 0;
e = ev;
end = (void *) ev + len;
end = e + count;
for (e = ev; e < end; e++) {
time = e->time.tv_sec * 1000 + e->time.tv_usec / 1000;
@ -373,11 +356,43 @@ evdev_input_device_data(int fd, uint32_t mask, void *data)
}
evdev_flush_motion(device, time);
}
static int
evdev_input_device_data(int fd, uint32_t mask, void *data)
{
struct weston_compositor *ec;
struct evdev_input_device *device = data;
struct input_event ev[32];
int len;
ec = device->master->base.compositor;
if (!ec->focus)
return 1;
/* If the compositor is repainting, this function is called only once
* per frame and we have to process all the events available on the
* fd, otherwise there will be input lag. */
do {
if (device->mtdev)
len = mtdev_get(device->mtdev, fd, ev,
ARRAY_LENGTH(ev)) *
sizeof (struct input_event);
else
len = read(fd, &ev, sizeof ev);
if (len < 0 || len % sizeof ev[0] != 0) {
/* FIXME: call device_removed when errno is ENODEV. */
return 1;
}
evdev_process_events(device, ev, len / sizeof ev[0]);
} while (len > 0);
return 1;
}
/* copied from udev/extras/input_id/input_id.c */
/* we must use this kernel-compatible implementation */
#define BITS_PER_LONG (sizeof(unsigned long) * 8)
@ -463,7 +478,9 @@ evdev_input_device_create(struct evdev_input *master,
device->rel.dx = 0;
device->rel.dy = 0;
/* if O_NONBLOCK is not set, mtdev_get() blocks */
/* Use non-blocking mode so that we can loop on read on
* evdev_input_device_data() until all events on the fd are
* read. mtdev_get() also expects this. */
device->fd = open(path, O_RDONLY | O_NONBLOCK);
if (device->fd < 0)
goto err0;