[PATCH] pwc: do not block in VIDIOC_DQBUF

[PATCH] pwc: do not block in VIDIOC_DQBUF

[audetto]

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I think the ioctl VIDIOC_DQBUF in pwc does not follow the API spec.
It should not block if there are no buffers and the device has been 
opened with O_NONBLOCK.

I am not sure the patch is 100% correct, since I do not understand it 
completely.

Andrea



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diff -r 87aa6048e718 linux/drivers/media/video/pwc/pwc-v4l.c
--- a/linux/drivers/media/video/pwc/pwc-v4l.c	Wed Jul 02 08:59:38 2008 -0300
+++ b/linux/drivers/media/video/pwc/pwc-v4l.c	Sat Jul 05 14:14:03 2008 +0100
@@ -1134,6 +1134,13 @@
 				     frameq is safe now.
 			 */
 			add_wait_queue(&pdev->frameq, &wait);
+
+			if ((pdev->full_frames == NULL) && (file->f_flags & O_NONBLOCK)) {
+				remove_wait_queue(&pdev->frameq, &wait);
+				set_current_state(TASK_RUNNING);
+				return -EAGAIN;
+			}
+
 			while (pdev->full_frames == NULL) {
 				if (pdev->error_status) {
 					remove_wait_queue(&pdev->frameq, &wait);

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Re: [PATCH] pwc: do not block in VIDIOC_DQBUF

[Andrea]

audetto@tiscali.it wrote:
> I think the ioctl VIDIOC_DQBUF in pwc does not follow the API spec.
> It should not block if there are no buffers and the device has been 
> opened with O_NONBLOCK.
> 
> I am not sure the patch is 100% correct, since I do not understand it 
> completely.
> 
> Andrea

Anybody to review this patch?

The documentation of VIDIOC_DQBUF is at

http://www.linuxtv.org/downloads/video4linux/API/V4L2_API/spec/r8849.htm

diff -r 87aa6048e718 linux/drivers/media/video/pwc/pwc-v4l.c
--- a/linux/drivers/media/video/pwc/pwc-v4l.c   Wed Jul 02 08:59:38 2008 -0300
+++ b/linux/drivers/media/video/pwc/pwc-v4l.c   Mon Jul 07 21:17:49 2008 +0100
@@ -1134,6 +1136,13 @@
                                      frameq is safe now.
                          */
                         add_wait_queue(&pdev->frameq, &wait);
+
+                       if ((pdev->full_frames == NULL) && (file->f_flags & O_NONBLOCK)) {
+                               remove_wait_queue(&pdev->frameq, &wait);
+                               set_current_state(TASK_RUNNING);
+                               return -EAGAIN;
+                       }
+
                         while (pdev->full_frames == NULL) {
                                 if (pdev->error_status) {
                                         remove_wait_queue(&pdev->frameq, &wait);


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