Hi Tomasz,
I like the direction in which you are going with the userspace
handling. This is almost exactly as I envisioned it. I have one
comment though:
On Thu, Jan 26, 2012 at 01:48, Tomasz Stanislawski
<t.stanislaws@xxxxxxxxxxx> wrote:
[snip]
> /* setup polling */
> struct pollfd fds[2] = {
> { .fd = f_in, .events = POLLIN },
> { .fd = f_out, .events = POLLOUT },
> };
>
> while ((ret = poll(fds, 2, 5000)) > 0) {
> struct v4l2_buffer buf;
> struct v4l2_plane plane;
>
> memset(&buf, 0, sizeof buf);
> memset(&plane, 0, sizeof plane);
> buf.m.planes = &plane;
> buf.length = 1;
>
> if (fds[0].revents & POLLIN) {
> /* dequeue buffer */
> buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE;
> buf.memory = V4L2_MEMORY_MMAP;
> ret = ioctl(f_in, VIDIOC_DQBUF, &buf);
> BYE_ON(ret, "VIDIOC_DQBUF failed: %s\n", ERRSTR);
>
> /* enqueue buffer */
> buf.type = V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE;
> buf.memory = V4L2_MEMORY_DMABUF;
> plane.m.fd = fd[buf.index];
> ret = ioctl(f_out, VIDIOC_QBUF, &buf);
> BYE_ON(ret, "VIDIOC_QBUF failed: %s\n", ERRSTR);
> }
This passes fd, so the OUTPUT driver will get the correct buffer from dmabuf.
> if (fds[1].revents & POLLOUT) {
> /* dequeue buffer */
> buf.type = V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE;
> buf.memory = V4L2_MEMORY_DMABUF;
> ret = ioctl(f_out, VIDIOC_DQBUF, &buf);
> BYE_ON(ret, "VIDIOC_DQBUF failed: %s\n", ERRSTR);
>
> /* enqueue buffer */
> buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE;
> buf.memory = V4L2_MEMORY_MMAP;
> ret = ioctl(f_in, VIDIOC_QBUF, &buf);
> BYE_ON(ret, "VIDIOC_QBUF failed: %s\n", ERRSTR);
> }
This, however, relies on the indexes to be equal for the same
buffers/planes in both drivers. I don't see why we should restrict
ourselves to that. In fact, we must not. You should have a reverse
mapping of fd->index for the INPUT device and use the fd returned in
buf by DQBUF from OUTPUT device to look-up the correct index to be
passed to the INPUT device.
> }
>
> BYE_ON(ret == 0, "polling timeout\n");
> BYE_ON(1, "polling stopped: %s\n", ERRSTR);
>
> return 0;
> }
--
Best regards,
Pawel Osciak
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