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drm: Implement O_NONBLOCK support on /dev/dri/cardN 

The implmentation is simple in the extreme: we only want to wait for
events if the device was opened in blocking mode, otherwise we grab what
is available and report an error if there was none.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: dri-devel@lists.freedesktop.org
Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Testcase: igt/kms_flip/nonblocing_read
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
This commit is contained in:
Chris Wilson 2014-10-07 14:13:51 +01:00 committed by Daniel Vetter
parent 1bcecfacde
commit bd008e5b29
1 changed files with 7 additions and 5 deletions
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12
drivers/gpu/drm/drm_fops.c
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@ -515,10 +515,12 @@ ssize_t drm_read(struct file *filp, char __user *buffer,
size_t total;
ssize_t ret;
ret = wait_event_interruptible(file_priv->event_wait,
!list_empty(&file_priv->event_list));
if (ret < 0)
return ret;
if ((filp->f_flags & O_NONBLOCK) == 0) {
ret = wait_event_interruptible(file_priv->event_wait,
!list_empty(&file_priv->event_list));
if (ret < 0)
return ret;
}
total = 0;
while (drm_dequeue_event(file_priv, total, count, &e)) {
@ -532,7 +534,7 @@ ssize_t drm_read(struct file *filp, char __user *buffer,
e->destroy(e);
}
return total;
return total ?: -EAGAIN;
}
EXPORT_SYMBOL(drm_read);