30.04.2020 01:00, Sowjanya Komatineni пишет:
> +static int chan_capture_kthread_start(void *data)
> +{
> + struct tegra_vi_channel *chan = data;
> + struct tegra_channel_buffer *buf;
> + int err = 0;
> +
> + set_freezable();
> +
> + while (1) {
> + try_to_freeze();
> +
> + /*
> + * Source is not streaming if error is non-zero.
> + * So, do not dequeue buffers on error and let the thread sleep
> + * till kthread stop signal is received.
> + */
> + wait_event_interruptible(chan->start_wait,
> + kthread_should_stop() ||
> + (!list_empty(&chan->capture) &&
> + !err));
...
> +static void tegra_channel_buffer_queue(struct vb2_buffer *vb)
> +{
> + struct tegra_vi_channel *chan = vb2_get_drv_priv(vb->vb2_queue);
> + struct vb2_v4l2_buffer *vbuf = to_vb2_v4l2_buffer(vb);
> + struct tegra_channel_buffer *buf = to_tegra_channel_buffer(vbuf);
> +
> + /* put buffer into the capture queue */
> + spin_lock(&chan->start_lock);
> + list_add_tail(&buf->queue, &chan->capture);
> + spin_unlock(&chan->start_lock);
> +
> + /* wait up kthread for capture */
> + wake_up_interruptible(&chan->start_wait);
> +}
The V4L doc says that buffers could be enqueued before streaming is
started. I guess it should be a trouble here, shouldn't it?
https://elixir.bootlin.com/linux/v5.7-rc3/source/include/media/videobuf2-core.h#L379
