On Sun, 3 Apr 2011, Pawel Osciak wrote:
> Drivers are now required to implement the stop_streaming() callback
> to ensure that all ongoing hardware operations are finished and their
> ownership of buffers is ceded.
> Drivers do not have to call vb2_buffer_done() for each buffer they own
> anymore.
> Also remove the return value from the callback.
>
> Signed-off-by: Pawel Osciak <pawel@xxxxxxxxxx>
> ---
> drivers/media/video/videobuf2-core.c | 16 ++++++++++++++--
> include/media/videobuf2-core.h | 16 +++++++---------
> 2 files changed, 21 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/media/video/videobuf2-core.c b/drivers/media/video/videobuf2-core.c
> index 6e69584..59d5e8b 100644
> --- a/drivers/media/video/videobuf2-core.c
> +++ b/drivers/media/video/videobuf2-core.c
> @@ -640,6 +640,9 @@ void vb2_buffer_done(struct vb2_buffer *vb, enum vb2_buffer_state state)
> struct vb2_queue *q = vb->vb2_queue;
> unsigned long flags;
>
> + if (atomic_read(&q->queued_count) == 0)
> + return;
> +
> if (vb->state != VB2_BUF_STATE_ACTIVE)
> return;
>
> @@ -1178,12 +1181,20 @@ static void __vb2_queue_cancel(struct vb2_queue *q)
> unsigned int i;
>
> /*
> - * Tell driver to stop all transactions and release all queued
> + * Tell the driver to stop all transactions and release all queued
> * buffers.
> */
> if (q->streaming)
> call_qop(q, stop_streaming, q);
> +
> + /*
> + * All buffers should now not be in use by the driver anymore, but we
> + * have to manually set queued_count to 0, as the driver was not
> + * required to call vb2_buffer_done() from stop_streaming() for all
> + * buffers it had queued.
> + */
> q->streaming = 0;
> + atomic_set(&q->queued_count, 0);
>
> /*
> * Remove all buffers from videobuf's list...
> @@ -1197,7 +1208,7 @@ static void __vb2_queue_cancel(struct vb2_queue *q)
> wake_up_all(&q->done_wq);
>
> /*
> - * Reinitialize all buffers for next use.
> + * Reinitialize all buffers for future use.
> */
> for (i = 0; i < q->num_buffers; ++i)
> q->bufs[i]->state = VB2_BUF_STATE_DEQUEUED;
> @@ -1440,6 +1451,7 @@ int vb2_queue_init(struct vb2_queue *q)
>
> BUG_ON(!q->ops->queue_setup);
> BUG_ON(!q->ops->buf_queue);
> + BUG_ON(!q->ops->stop_streaming);
>
> INIT_LIST_HEAD(&q->queued_list);
> INIT_LIST_HEAD(&q->done_list);
> diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h
> index f3bdbb2..8115fe9 100644
> --- a/include/media/videobuf2-core.h
> +++ b/include/media/videobuf2-core.h
> @@ -184,7 +184,7 @@ struct vb2_buffer {
>
> /**
> * struct vb2_ops - driver-specific callbacks to be implemented by the driver
> - * Required: queue_setup, buf_queue. The rest is optional.
> + * Required: queue_setup, buf_queue, stop_streaming. The rest is optional.
> *
> * @queue_setup: used to negotiate queue parameters between the userspace
> * and the driver; called before memory allocation;
> @@ -231,13 +231,11 @@ struct vb2_buffer {
> * the driver before streaming begins (such as enabling
> * the device);
> * @stop_streaming: called when the 'streaming' state must be disabled;
> - * drivers should stop any DMA transactions here (or wait
> - * until they are finished) and give back all the buffers
> - * received via buf_queue() by calling vb2_buffer_done()
> - * for each of them;
> - * drivers can use the vb2_wait_for_all_buffers() function
> - * here to wait for asynchronous completion events that
> - * call vb2_buffer_done(), such as ISRs;
> + * drivers should stop any DMA transactions here (or wait
> + * until they are finished) before returning;
> + * drivers can use the vb2_wait_for_all_buffers() function
> + * here to wait for asynchronous completion events, such
> + * as ISRs;
> * @buf_queue: passes a buffer to the driver; the driver may start
> * a hardware operation on that buffer; this callback
> * MUST return immediately, i.e. it may NOT wait for
> @@ -259,7 +257,7 @@ struct vb2_ops {
> void (*buf_cleanup)(struct vb2_buffer *vb);
>
> int (*start_streaming)(struct vb2_queue *q);
> - int (*stop_streaming)(struct vb2_queue *q);
> + void (*stop_streaming)(struct vb2_queue *q);
Won't compilation break after this patch with "assignment from
incompatible pointer type?" I know, it's only until it is fixed by the
follow-up patches, but normally we're trying to avoid such bisection
breakages.
Thanks
Guennadi
>
> void (*buf_queue)(struct vb2_buffer *vb);
> };
> --
> 1.7.4.2
>
---
Guennadi Liakhovetski, Ph.D.
Freelance Open-Source Software Developer
http://www.open-technology.de/
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