Buffers can be returned back to videobuf2 in driver's streamon handler. In
this case vb2_buffer_done() with buffer state VB2_BUF_STATE_QUEUED will
cause the driver's buf_queue vb2 operation to be called, queueing the same
buffer again only to be returned to videobuf2 using vb2_buffer_done() and so
on.

Add a new buffer state VB2_BUF_STATE_REQUEUEING which, when used as the
state argument to vb2_buffer_done(), will result in buffers queued to the
driver. Using VB2_BUF_STATE_QUEUED will leave the buffer to videobuf2, as it
was before "[media] vb2: allow requeuing buffers while streaming".

Fixes: ce0eff016f72 ("[media] vb2: allow requeuing buffers while streaming")
Signed-off-by: Sakari Ailus <sakari.ai...@linux.intel.com>
Acked-by: Hans Verkuil <hans.verk...@cisco.com>
Cc: sta...@vger.kernel.org # for v4.1
---
since v3:

- Added a break at the end of the default case in the switch in
  vb2_buffer_done().

 drivers/media/pci/cobalt/cobalt-irq.c    |  2 +-
 drivers/media/v4l2-core/videobuf2-core.c | 25 +++++++++++++++++--------
 include/media/videobuf2-core.h           |  2 ++
 3 files changed, 20 insertions(+), 9 deletions(-)

diff --git a/drivers/media/pci/cobalt/cobalt-irq.c 
b/drivers/media/pci/cobalt/cobalt-irq.c
index e18f49e..2687cb0 100644
--- a/drivers/media/pci/cobalt/cobalt-irq.c
+++ b/drivers/media/pci/cobalt/cobalt-irq.c
@@ -134,7 +134,7 @@ done:
           also know about dropped frames. */
        cb->vb.v4l2_buf.sequence = s->sequence++;
        vb2_buffer_done(&cb->vb, (skip || s->unstable_frame) ?
-                       VB2_BUF_STATE_QUEUED : VB2_BUF_STATE_DONE);
+                       VB2_BUF_STATE_REQUEUEING : VB2_BUF_STATE_DONE);
 }
 
 irqreturn_t cobalt_irq_handler(int irq, void *dev_id)
diff --git a/drivers/media/v4l2-core/videobuf2-core.c 
b/drivers/media/v4l2-core/videobuf2-core.c
index 1a096a6..45c571f 100644
--- a/drivers/media/v4l2-core/videobuf2-core.c
+++ b/drivers/media/v4l2-core/videobuf2-core.c
@@ -1182,7 +1182,8 @@ void vb2_buffer_done(struct vb2_buffer *vb, enum 
vb2_buffer_state state)
 
        if (WARN_ON(state != VB2_BUF_STATE_DONE &&
                    state != VB2_BUF_STATE_ERROR &&
-                   state != VB2_BUF_STATE_QUEUED))
+                   state != VB2_BUF_STATE_QUEUED &&
+                   state != VB2_BUF_STATE_REQUEUEING))
                state = VB2_BUF_STATE_ERROR;
 
 #ifdef CONFIG_VIDEO_ADV_DEBUG
@@ -1199,22 +1200,30 @@ void vb2_buffer_done(struct vb2_buffer *vb, enum 
vb2_buffer_state state)
        for (plane = 0; plane < vb->num_planes; ++plane)
                call_void_memop(vb, finish, vb->planes[plane].mem_priv);
 
-       /* Add the buffer to the done buffers list */
        spin_lock_irqsave(&q->done_lock, flags);
-       vb->state = state;
-       if (state != VB2_BUF_STATE_QUEUED)
+       if (state == VB2_BUF_STATE_QUEUED ||
+           state == VB2_BUF_STATE_REQUEUEING) {
+               vb->state = VB2_BUF_STATE_QUEUED;
+       } else {
+               /* Add the buffer to the done buffers list */
                list_add_tail(&vb->done_entry, &q->done_list);
+               vb->state = state;
+       }
        atomic_dec(&q->owned_by_drv_count);
        spin_unlock_irqrestore(&q->done_lock, flags);
 
-       if (state == VB2_BUF_STATE_QUEUED) {
+       switch (state) {
+       case VB2_BUF_STATE_QUEUED:
+               return;
+       case VB2_BUF_STATE_REQUEUEING:
                if (q->start_streaming_called)
                        __enqueue_in_driver(vb);
                return;
+       default:
+               /* Inform any processes that may be waiting for buffers */
+               wake_up(&q->done_wq);
+               break;
        }
-
-       /* Inform any processes that may be waiting for buffers */
-       wake_up(&q->done_wq);
 }
 EXPORT_SYMBOL_GPL(vb2_buffer_done);
 
diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h
index 22a44c2..c192e1b 100644
--- a/include/media/videobuf2-core.h
+++ b/include/media/videobuf2-core.h
@@ -139,6 +139,7 @@ enum vb2_io_modes {
  * @VB2_BUF_STATE_PREPARING:   buffer is being prepared in videobuf
  * @VB2_BUF_STATE_PREPARED:    buffer prepared in videobuf and by the driver
  * @VB2_BUF_STATE_QUEUED:      buffer queued in videobuf, but not in driver
+ * @VB2_BUF_STATE_REQUEUEING:  re-queue a buffer to the driver
  * @VB2_BUF_STATE_ACTIVE:      buffer queued in driver and possibly used
  *                             in a hardware operation
  * @VB2_BUF_STATE_DONE:                buffer returned from driver to 
videobuf, but
@@ -152,6 +153,7 @@ enum vb2_buffer_state {
        VB2_BUF_STATE_PREPARING,
        VB2_BUF_STATE_PREPARED,
        VB2_BUF_STATE_QUEUED,
+       VB2_BUF_STATE_REQUEUEING,
        VB2_BUF_STATE_ACTIVE,
        VB2_BUF_STATE_DONE,
        VB2_BUF_STATE_ERROR,
-- 
2.1.4

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