Em Fri, 16 Jun 2017 16:39:06 +0900
Gustavo Padovan <gustavo@xxxxxxxxxxx> escreveu:
> From: Gustavo Padovan <gustavo.padovan@xxxxxxxxxxxxx>
>
> Receive in-fence from userspace and add support for waiting on them
> before queueing the buffer to the driver. Buffers are only queued
> to the driver once they are ready. A buffer is ready when its
> in-fence signals.
>
> v2:
> - fix vb2_queue_or_prepare_buf() ret check
> - remove check for VB2_MEMORY_DMABUF only (Javier)
> - check num of ready buffers to start streaming
> - when queueing, start from the first ready buffer
> - handle queue cancel
>
> Signed-off-by: Gustavo Padovan <gustavo.padovan@xxxxxxxxxxxxx>
> ---
> drivers/media/Kconfig | 1 +
> drivers/media/v4l2-core/videobuf2-core.c | 97 +++++++++++++++++++++++++-------
> drivers/media/v4l2-core/videobuf2-v4l2.c | 15 ++++-
> include/media/videobuf2-core.h | 7 ++-
> 4 files changed, 99 insertions(+), 21 deletions(-)
>
> diff --git a/drivers/media/Kconfig b/drivers/media/Kconfig
> index 55d9c2b..3cd1d3d 100644
> --- a/drivers/media/Kconfig
> +++ b/drivers/media/Kconfig
> @@ -11,6 +11,7 @@ config CEC_NOTIFIER
> menuconfig MEDIA_SUPPORT
> tristate "Multimedia support"
> depends on HAS_IOMEM
> + select SYNC_FILE
> help
> If you want to use Webcams, Video grabber devices and/or TV devices
> enable this option and other options below.
> diff --git a/drivers/media/v4l2-core/videobuf2-core.c b/drivers/media/v4l2-core/videobuf2-core.c
> index ea83126..29aa9d4 100644
> --- a/drivers/media/v4l2-core/videobuf2-core.c
> +++ b/drivers/media/v4l2-core/videobuf2-core.c
> @@ -1279,6 +1279,22 @@ static int __buf_prepare(struct vb2_buffer *vb, const void *pb)
> return 0;
> }
>
> +static int __get_num_ready_buffers(struct vb2_queue *q)
> +{
> + struct vb2_buffer *vb;
> + int ready_count = 0;
> +
> + /* count num of buffers ready in front of the queued_list */
> + list_for_each_entry(vb, &q->queued_list, queued_entry) {
> + if (vb->in_fence && !dma_fence_is_signaled(vb->in_fence))
> + break;
> +
> + ready_count++;
Hmm... maybe that's one of the reasons why out of order explicit fences is not
working. With the current logic, if explicit fences is enabled, this function
will always return 0 or 1, even if more buffers are ready.
IMHO, the correct logic here should be, instead:
if (!vb->in_fence || dma_fence_is_signaled(vb->in_fence))
ready_count++;
> + }
> +
> + return ready_count;
> +}
> +
> int vb2_core_prepare_buf(struct vb2_queue *q, unsigned int index, void *pb)
> {
> struct vb2_buffer *vb;
> @@ -1324,8 +1340,15 @@ static int vb2_start_streaming(struct vb2_queue *q)
> * If any buffers were queued before streamon,
> * we can now pass them to driver for processing.
> */
> - list_for_each_entry(vb, &q->queued_list, queued_entry)
> + list_for_each_entry(vb, &q->queued_list, queued_entry) {
> + if (vb->state != VB2_BUF_STATE_QUEUED)
> + continue;
> +
> + if (vb->in_fence && !dma_fence_is_signaled(vb->in_fence))
> + break;
> +
> __enqueue_in_driver(vb);
Same as before, the correct logic here seems to be:
if (!vb->in_fence || dma_fence_is_signaled(vb->in_fence))
__enqueue_in_driver(vb);
> + }
>
> /* Tell the driver to start streaming */
> q->start_streaming_called = 1;
> @@ -1369,33 +1392,55 @@ static int vb2_start_streaming(struct vb2_queue *q)
>
> static int __vb2_core_qbuf(struct vb2_buffer *vb, struct vb2_queue *q)
> {
> + struct vb2_buffer *b;
> int ret;
>
> /*
> * If already streaming, give the buffer to driver for processing.
> * If not, the buffer will be given to driver on next streamon.
> */
> - if (q->start_streaming_called)
> - __enqueue_in_driver(vb);
>
> - /*
> - * If streamon has been called, and we haven't yet called
> - * start_streaming() since not enough buffers were queued, and
> - * we now have reached the minimum number of queued buffers,
> - * then we can finally call start_streaming().
> - */
> - if (q->streaming && !q->start_streaming_called &&
> - q->queued_count >= q->min_buffers_needed) {
> - ret = vb2_start_streaming(q);
> - if (ret)
> - return ret;
> + if (q->start_streaming_called) {
> + list_for_each_entry(b, &q->queued_list, queued_entry) {
> + if (b->state != VB2_BUF_STATE_QUEUED)
> + continue;
> +
> + if (b->in_fence && !dma_fence_is_signaled(b->in_fence))
> + break;
> +
> + __enqueue_in_driver(b);
Same here:
if (!vb->in_fence || dma_fence_is_signaled(vb->in_fence))
__enqueue_in_driver(vb);
There is, however, a behavior change here (even without the above
proposal.
Before this patch, if fences is not used (for example, for DVB or
for some other mechanism at V4L2), the driver would be doing:
if (q->start_streaming_called)
__enqueue_in_driver(vb);
So, __enqueue_in_driver() would be called just once. Now, after
the change, it will be doing, instead:
list_for_each_entry(vb, &q->queued_list, queued_entry)
__enqueue_in_driver(vb);
With can queue several buffers at once.
I've no idea how this will affect non-fences behavior for V4L2
and for DVB. More tests are required to check if this badly affect
drivers, or if it would bring some performance or latency change.
> + }
> + } else {
Why did you add an else here? I guess there was a very strong reason
to not have an else at the original code - just can't remember why, and
I' too lazy today to dig into VB2 changeset descriptions :-)
Please don't change the behavior together with a patch that add new
features as it can cause regressions, and it would be a way harder
to track if you fold different changes at the same patch.
If this behavior change is due to some bug, it should be submitted
in a separate, patch, provided with a very detailed description.
If otherwise, this is a requiement just for fences, you should first
test if fences is enabled before changing the behavior.
> + /*
> + * If streamon has been called, and we haven't yet called
> + * start_streaming() since not enough buffers were queued, and
> + * we now have reached the minimum number of queued buffers
> + * that are ready, then we can finally call start_streaming().
> + */
> + if (q->streaming &&
> + __get_num_ready_buffers(q) >= q->min_buffers_needed) {
> + ret = vb2_start_streaming(q);
> + if (ret)
> + return ret;
> + }
> }
>
> dprintk(1, "qbuf of buffer %d succeeded\n", vb->index);
> return 0;
> }
>
> -int vb2_core_qbuf(struct vb2_queue *q, unsigned int index, void *pb)
> +static void vb2_qbuf_fence_cb(struct dma_fence *f, struct dma_fence_cb *cb)
> +{
> + struct vb2_buffer *vb = container_of(cb, struct vb2_buffer, fence_cb);
> +
> + dma_fence_put(vb->in_fence);
> + vb->in_fence = NULL;
> +
> + __vb2_core_qbuf(vb, vb->vb2_queue);
> +}
> +
> +int vb2_core_qbuf(struct vb2_queue *q, unsigned int index, void *pb,
> + struct dma_fence *fence)
> {
> struct vb2_buffer *vb;
> int ret;
> @@ -1436,6 +1481,11 @@ int vb2_core_qbuf(struct vb2_queue *q, unsigned int index, void *pb)
> if (pb)
> call_void_bufop(q, fill_user_buffer, vb, pb);
>
> + vb->in_fence = fence;
> + if (fence && !dma_fence_add_callback(fence, &vb->fence_cb,
> + vb2_qbuf_fence_cb))
> + return 0;
Maybe we should provide some error or debug log here or a WARN_ON(), if
dma_fence_add_callback() fails instead of silently ignore any errors.
> +
> return __vb2_core_qbuf(vb, q);
> }
> EXPORT_SYMBOL_GPL(vb2_core_qbuf);
> @@ -1647,6 +1697,7 @@ EXPORT_SYMBOL_GPL(vb2_core_dqbuf);
> static void __vb2_queue_cancel(struct vb2_queue *q)
> {
> unsigned int i;
> + struct vb2_buffer *vb;
>
> /*
> * Tell driver to stop all transactions and release all queued
> @@ -1669,6 +1720,14 @@ static void __vb2_queue_cancel(struct vb2_queue *q)
> WARN_ON(atomic_read(&q->owned_by_drv_count));
> }
>
> + list_for_each_entry(vb, &q->queued_list, queued_entry) {
> + if (vb->in_fence) {
> + dma_fence_remove_callback(vb->in_fence, &vb->fence_cb);
> + dma_fence_put(vb->in_fence);
> + vb->in_fence = NULL;
> + }
> + }
> +
> q->streaming = 0;
> q->start_streaming_called = 0;
> q->queued_count = 0;
> @@ -1735,7 +1794,7 @@ int vb2_core_streamon(struct vb2_queue *q, unsigned int type)
> * Tell driver to start streaming provided sufficient buffers
> * are available.
> */
> - if (q->queued_count >= q->min_buffers_needed) {
> + if (__get_num_ready_buffers(q) >= q->min_buffers_needed) {
> ret = v4l_vb2q_enable_media_source(q);
> if (ret)
> return ret;
> @@ -2250,7 +2309,7 @@ static int __vb2_init_fileio(struct vb2_queue *q, int read)
> * Queue all buffers.
> */
> for (i = 0; i < q->num_buffers; i++) {
> - ret = vb2_core_qbuf(q, i, NULL);
> + ret = vb2_core_qbuf(q, i, NULL, NULL);
> if (ret)
> goto err_reqbufs;
> fileio->bufs[i].queued = 1;
> @@ -2429,7 +2488,7 @@ static size_t __vb2_perform_fileio(struct vb2_queue *q, char __user *data, size_
>
> if (copy_timestamp)
> b->timestamp = ktime_get_ns();
> - ret = vb2_core_qbuf(q, index, NULL);
> + ret = vb2_core_qbuf(q, index, NULL, NULL);
> dprintk(5, "vb2_dbuf result: %d\n", ret);
> if (ret)
> return ret;
> @@ -2532,7 +2591,7 @@ static int vb2_thread(void *data)
> if (copy_timestamp)
> vb->timestamp = ktime_get_ns();;
> if (!threadio->stop)
> - ret = vb2_core_qbuf(q, vb->index, NULL);
> + ret = vb2_core_qbuf(q, vb->index, NULL, NULL);
> call_void_qop(q, wait_prepare, q);
> if (ret || threadio->stop)
> break;
> diff --git a/drivers/media/v4l2-core/videobuf2-v4l2.c b/drivers/media/v4l2-core/videobuf2-v4l2.c
> index 110fb45..e6ad77f 100644
> --- a/drivers/media/v4l2-core/videobuf2-v4l2.c
> +++ b/drivers/media/v4l2-core/videobuf2-v4l2.c
> @@ -23,6 +23,7 @@
> #include <linux/sched.h>
> #include <linux/freezer.h>
> #include <linux/kthread.h>
> +#include <linux/sync_file.h>
>
> #include <media/v4l2-dev.h>
> #include <media/v4l2-fh.h>
> @@ -560,6 +561,7 @@ EXPORT_SYMBOL_GPL(vb2_create_bufs);
>
> int vb2_qbuf(struct vb2_queue *q, struct v4l2_buffer *b)
> {
> + struct dma_fence *fence = NULL;
> int ret;
>
> if (vb2_fileio_is_active(q)) {
> @@ -568,7 +570,18 @@ int vb2_qbuf(struct vb2_queue *q, struct v4l2_buffer *b)
> }
>
> ret = vb2_queue_or_prepare_buf(q, b, "qbuf");
> - return ret ? ret : vb2_core_qbuf(q, b->index, b);
> + if (ret)
> + return ret;
> +
> + if (b->flags & V4L2_BUF_FLAG_IN_FENCE) {
> + fence = sync_file_get_fence(b->fence_fd);
> + if (!fence) {
> + dprintk(1, "failed to get in-fence from fd\n");
> + return -EINVAL;
> + }
> + }
> +
> + return ret ? ret : vb2_core_qbuf(q, b->index, b, fence);
No need to check for ret again. You could just do:
return vb2_core_qbuf(q, b->index, b, fence);
> }
> EXPORT_SYMBOL_GPL(vb2_qbuf);
>
> diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h
> index cb97c22..aa43e43 100644
> --- a/include/media/videobuf2-core.h
> +++ b/include/media/videobuf2-core.h
> @@ -16,6 +16,7 @@
> #include <linux/mutex.h>
> #include <linux/poll.h>
> #include <linux/dma-buf.h>
> +#include <linux/dma-fence.h>
>
> #define VB2_MAX_FRAME (32)
> #define VB2_MAX_PLANES (8)
> @@ -259,6 +260,9 @@ struct vb2_buffer {
>
> struct list_head queued_entry;
> struct list_head done_entry;
> +
> + struct dma_fence *in_fence;
> + struct dma_fence_cb fence_cb;
> #ifdef CONFIG_VIDEO_ADV_DEBUG
> /*
> * Counters for how often these buffer-related ops are
> @@ -727,7 +731,8 @@ int vb2_core_prepare_buf(struct vb2_queue *q, unsigned int index, void *pb);
> * The return values from this function are intended to be directly returned
> * from vidioc_qbuf handler in driver.
> */
> -int vb2_core_qbuf(struct vb2_queue *q, unsigned int index, void *pb);
> +int vb2_core_qbuf(struct vb2_queue *q, unsigned int index, void *pb,
> + struct dma_fence *fence);
>
> /**
> * vb2_core_dqbuf() - Dequeue a buffer to the userspace
--
Thanks,
Mauro
