[media] pwc: Replace private buffer management code with videobuf2

Looking at the pwc buffer management code has made it clear to me it needed
some serious fixing. Not only was there a ton of code duplication even
internally to pwc (read and mmap wait for frame code was duplicated), the
code also was outright buggy. With the worst offender being dqbuf, which
just round robin returned all the mmap buffers, without paying any attention
to them being queued by the app with qbuf or not. And qbuf itself was a noop.

So I set out to fix this and already had some cleanups in place when
I read Jonathan Corbet's lwn article on videobuf2, this inspired me to just
rip out the buffer management code and replace it with videobuf2, greatly
reducing the amount of code, and fixing all bugs in one go:

Many thanks to Jonathan for the timely article on this !

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

1 files changed, 11 insertions, 114 deletions

diff --git a/drivers/media/video/pwc/pwc-v4l.c b/drivers/media/video/pwc/pwc-v4l.c
index 8e72e0f56550..cda38837adcd 100644
--- a/drivers/media/video/pwc/pwc-v4l.c
+++ b/drivers/media/video/pwc/pwc-v4l.c
@@ -309,7 +309,7 @@ static int pwc_vidioc_set_fmt(struct pwc_device *pdev, struct v4l2_format *f)
 	    pixelformat != V4L2_PIX_FMT_PWC2)
 		return -EINVAL;
 
-	if (pdev->iso_init)
+	if (vb2_is_streaming(&pdev->vb_queue))
 		return -EBUSY;
 
 	PWC_DEBUG_IOCTL("Trying to set format to: width=%d height=%d fps=%d "
@@ -673,150 +673,47 @@ static int pwc_s_fmt_vid_cap(struct file *file, void *fh, struct v4l2_format *f)
 	return pwc_vidioc_set_fmt(pdev, f);
 }
 
-static int pwc_reqbufs(struct file *file, void *fh, struct v4l2_requestbuffers *rb)
+static int pwc_reqbufs(struct file *file, void *fh,
+		       struct v4l2_requestbuffers *rb)
 {
-	int nbuffers;
-
-	PWC_DEBUG_IOCTL("ioctl(VIDIOC_REQBUFS) count=%d\n", rb->count);
-	if (rb->type != V4L2_BUF_TYPE_VIDEO_CAPTURE)
-		return -EINVAL;
-	if (rb->memory != V4L2_MEMORY_MMAP)
-		return -EINVAL;
+	struct pwc_device *pdev = video_drvdata(file);
 
-	nbuffers = rb->count;
-	if (nbuffers < 2)
-		nbuffers = 2;
-	else if (nbuffers > pwc_mbufs)
-		nbuffers = pwc_mbufs;
-	/* Force to use our # of buffers */
-	rb->count = pwc_mbufs;
-	return 0;
+	return vb2_reqbufs(&pdev->vb_queue, rb);
 }
 
 static int pwc_querybuf(struct file *file, void *fh, struct v4l2_buffer *buf)
 {
 	struct pwc_device *pdev = video_drvdata(file);
-	int index;
 
-	PWC_DEBUG_IOCTL("ioctl(VIDIOC_QUERYBUF) index=%d\n", buf->index);
-	if (buf->type != V4L2_BUF_TYPE_VIDEO_CAPTURE) {
-		PWC_DEBUG_IOCTL("ioctl(VIDIOC_QUERYBUF) Bad type\n");
-		return -EINVAL;
-	}
-	index = buf->index;
-	if (index < 0 || index >= pwc_mbufs) {
-		PWC_DEBUG_IOCTL("ioctl(VIDIOC_QUERYBUF) Bad index %d\n", buf->index);
-		return -EINVAL;
-	}
-
-	buf->m.offset = index * pdev->len_per_image;
-	if (pdev->pixfmt != V4L2_PIX_FMT_YUV420)
-		buf->bytesused = pdev->frame_size + sizeof(struct pwc_raw_frame);
-	else
-		buf->bytesused = pdev->view.size;
-	buf->field = V4L2_FIELD_NONE;
-	buf->memory = V4L2_MEMORY_MMAP;
-	/*buf->flags = V4L2_BUF_FLAG_MAPPED;*/
-	buf->length = pdev->len_per_image;
-
-	PWC_DEBUG_READ("VIDIOC_QUERYBUF: index=%d\n", buf->index);
-	PWC_DEBUG_READ("VIDIOC_QUERYBUF: m.offset=%d\n", buf->m.offset);
-	PWC_DEBUG_READ("VIDIOC_QUERYBUF: bytesused=%d\n", buf->bytesused);
-
-	return 0;
+	return vb2_querybuf(&pdev->vb_queue, buf);
 }
 
 static int pwc_qbuf(struct file *file, void *fh, struct v4l2_buffer *buf)
 {
-	PWC_DEBUG_IOCTL("ioctl(VIDIOC_QBUF) index=%d\n", buf->index);
-	if (buf->type != V4L2_BUF_TYPE_VIDEO_CAPTURE)
-		return -EINVAL;
-	if (buf->memory != V4L2_MEMORY_MMAP)
-		return -EINVAL;
-	if (buf->index >= pwc_mbufs)
-		return -EINVAL;
-
-	buf->flags |= V4L2_BUF_FLAG_QUEUED;
-	buf->flags &= ~V4L2_BUF_FLAG_DONE;
+	struct pwc_device *pdev = video_drvdata(file);
 
-	return 0;
+	return vb2_qbuf(&pdev->vb_queue, buf);
 }
 
 static int pwc_dqbuf(struct file *file, void *fh, struct v4l2_buffer *buf)
 {
-	DECLARE_WAITQUEUE(wait, current);
 	struct pwc_device *pdev = video_drvdata(file);
-	int ret;
-
-	PWC_DEBUG_IOCTL("ioctl(VIDIOC_DQBUF)\n");
-
-	if (buf->type != V4L2_BUF_TYPE_VIDEO_CAPTURE)
-		return -EINVAL;
-
-	add_wait_queue(&pdev->frameq, &wait);
-	while (pdev->full_frames == NULL) {
-		if (pdev->error_status) {
-			remove_wait_queue(&pdev->frameq, &wait);
-			set_current_state(TASK_RUNNING);
-			return -pdev->error_status;
-		}
-
-		if (signal_pending(current)) {
-			remove_wait_queue(&pdev->frameq, &wait);
-			set_current_state(TASK_RUNNING);
-			return -ERESTARTSYS;
-		}
-		mutex_unlock(&pdev->modlock);
-		schedule();
-		set_current_state(TASK_INTERRUPTIBLE);
-		mutex_lock(&pdev->modlock);
-	}
-	remove_wait_queue(&pdev->frameq, &wait);
-	set_current_state(TASK_RUNNING);
-
-	PWC_DEBUG_IOCTL("VIDIOC_DQBUF: frame ready.\n");
-	/* Decompress data in pdev->images[pdev->fill_image] */
-	ret = pwc_handle_frame(pdev);
-	if (ret)
-		return ret;
-	PWC_DEBUG_IOCTL("VIDIOC_DQBUF: after pwc_handle_frame\n");
-
-	buf->index = pdev->fill_image;
-	if (pdev->pixfmt != V4L2_PIX_FMT_YUV420)
-		buf->bytesused = pdev->frame_size + sizeof(struct pwc_raw_frame);
-	else
-		buf->bytesused = pdev->view.size;
-	buf->flags = V4L2_BUF_FLAG_MAPPED;
-	buf->field = V4L2_FIELD_NONE;
-	do_gettimeofday(&buf->timestamp);
-	buf->sequence = 0;
-	buf->memory = V4L2_MEMORY_MMAP;
-	buf->m.offset = pdev->fill_image * pdev->len_per_image;
-	buf->length = pdev->len_per_image;
-	pwc_next_image(pdev);
-
-	PWC_DEBUG_IOCTL("VIDIOC_DQBUF: buf->index=%d\n", buf->index);
-	PWC_DEBUG_IOCTL("VIDIOC_DQBUF: buf->length=%d\n", buf->length);
-	PWC_DEBUG_IOCTL("VIDIOC_DQBUF: m.offset=%d\n", buf->m.offset);
-	PWC_DEBUG_IOCTL("VIDIOC_DQBUF: bytesused=%d\n", buf->bytesused);
-	PWC_DEBUG_IOCTL("VIDIOC_DQBUF: leaving\n");
-	return 0;
 
+	return vb2_dqbuf(&pdev->vb_queue, buf, file->f_flags & O_NONBLOCK);
 }
 
 static int pwc_streamon(struct file *file, void *fh, enum v4l2_buf_type i)
 {
 	struct pwc_device *pdev = video_drvdata(file);
 
-	return pwc_isoc_init(pdev);
+	return vb2_streamon(&pdev->vb_queue, i);
 }
 
 static int pwc_streamoff(struct file *file, void *fh, enum v4l2_buf_type i)
 {
 	struct pwc_device *pdev = video_drvdata(file);
 
-	pwc_isoc_cleanup(pdev);
-	return 0;
+	return vb2_streamoff(&pdev->vb_queue, i);
 }
 
 static int pwc_enum_framesizes(struct file *file, void *fh,