Tomasz,

I've encountered an issue with this patch when userspace does several
stream_on/stream_off cycles. When the user tries to qbuf a buffer
after doing stream_off, we trigger the "dmabuf already pinned" warning
since we didn't unmap the buffer as dqbuf was never called.

The below patch adds calls to unmap in queue_cancel, but my feeling is that we
probably should be calling detach too (i.e. put_dmabuf).

Thoughts?

--Dima

Subject: [PATCH] v4l: vb2: unmap dmabufs on STREAM_OFF event

Currently, if the user issues a STREAM_OFF request and then
tries to re-enqueue buffers, it will trigger a warning in
the vb2 allocators as the buffer would still be mapped
from before STREAM_OFF was called. The current expectation
is that buffers will be unmapped in dqbuf, but that will never
be called on the mapped buffers after a STREAM_OFF event.

Cc: Sumit Semwal <sumit.sem...@ti.com>
Cc: Tomasz Stanislawski <t.stanisl...@samsung.com>
Signed-off-by: Dima Zavin <d...@android.com>
---
 drivers/media/video/videobuf2-core.c |   22 ++++++++++++++++++++--
 1 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/drivers/media/video/videobuf2-core.c 
b/drivers/media/video/videobuf2-core.c
index b431dc6..e2a8f12 100644
--- a/drivers/media/video/videobuf2-core.c
+++ b/drivers/media/video/videobuf2-core.c
@@ -1592,8 +1592,26 @@ static void __vb2_queue_cancel(struct vb2_queue *q)
        /*
         * Reinitialize all buffers for next use.
         */
-       for (i = 0; i < q->num_buffers; ++i)
-               q->bufs[i]->state = VB2_BUF_STATE_DEQUEUED;
+       for (i = 0; i < q->num_buffers; ++i) {
+               struct vb2_buffer *vb = q->bufs[i];
+               int plane;
+
+               vb->state = VB2_BUF_STATE_DEQUEUED;
+
+               if (q->memory != V4L2_MEMORY_DMABUF)
+                       continue;
+
+               for (plane = 0; plane < vb->num_planes; ++plane) {
+                       struct vb2_plane *p = &vb->planes[plane];
+
+                       if (!p->mem_priv)
+                               continue;
+                       if (p->dbuf_mapped) {
+                               call_memop(q, unmap_dmabuf, p->mem_priv);
+                               p->dbuf_mapped = 0;
+                       }
+               }
+       }
 }
 
 /**
-- 
1.7.7.3

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