linux-kernel - [RFC PATCH 2/2] [media] vb2: move dma-buf unmap from __vb2_dqbuf() to vb2_done

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Date:	Wed, 17 Aug 2016 14:28:57 -0400
From:	Javier Martinez Canillas <javier@....samsung.com>
To:	linux-kernel@...r.kernel.org
Cc:	Hans Verkuil <hverkuil@...all.nl>,
	Sakari Ailus <sakari.ailus@...ux.intel.com>,
	Javier Martinez Canillas <javier@....samsung.com>,
	Mauro Carvalho Chehab <mchehab@...nel.org>,
	Marek Szyprowski <m.szyprowski@...sung.com>,
	Kyungmin Park <kyungmin.park@...sung.com>,
	Pawel Osciak <pawel@...iak.com>, linux-media@...r.kernel.org
Subject: [RFC PATCH 2/2] [media] vb2: move dma-buf unmap from __vb2_dqbuf() to vb2_done_work()

Currently the dma-buf is unmapped when the buffer is dequeued by userspace
but it's not used anymore after the driver finished processing the buffer.

So instead of doing the dma-buf unmapping in __vb2_dqbuf(), it can be made
in vb2_done_work() after the driver notified that has finished processing.

Signed-off-by: Javier Martinez Canillas <javier@....samsung.com>

---

 drivers/media/v4l2-core/videobuf2-core.c | 33 ++++++++++++++++++++------------
 1 file changed, 21 insertions(+), 12 deletions(-)

diff --git a/drivers/media/v4l2-core/videobuf2-core.c b/drivers/media/v4l2-core/videobuf2-core.c
index 14bed8acf3cf..5f930dbedfa4 100644
--- a/drivers/media/v4l2-core/videobuf2-core.c
+++ b/drivers/media/v4l2-core/videobuf2-core.c
@@ -315,6 +315,21 @@ static void __setup_offsets(struct vb2_buffer *vb)
 	}
 }
 
+ /**
+ * __vb2_unmap_dmabuf() - unmap dma-buf attached to buffer planes
+ */
+static void __vb2_unmap_dmabuf(struct vb2_buffer *vb)
+{
+	int i;
+
+	for (i = 0; i < vb->num_planes; ++i) {
+		if (!vb->planes[i].dbuf_mapped)
+			continue;
+		call_void_memop(vb, unmap_dmabuf, vb->planes[i].mem_priv);
+		vb->planes[i].dbuf_mapped = 0;
+	}
+}
+
 static void vb2_done_work(struct work_struct *work)
 {
 	struct vb2_buffer *vb = container_of(work, struct vb2_buffer,
@@ -348,6 +363,9 @@ static void vb2_done_work(struct work_struct *work)
 			__enqueue_in_driver(vb);
 		break;
 	default:
+		if (q->memory == VB2_MEMORY_DMABUF)
+			__vb2_unmap_dmabuf(vb);
+
 		/* Inform any processes that may be waiting for buffers */
 		wake_up(&q->done_wq);
 		break;
@@ -1725,23 +1743,11 @@ EXPORT_SYMBOL_GPL(vb2_wait_for_all_buffers);
  */
 static void __vb2_dqbuf(struct vb2_buffer *vb)
 {
-	struct vb2_queue *q = vb->vb2_queue;
-	unsigned int i;
-
 	/* nothing to do if the buffer is already dequeued */
 	if (vb->state == VB2_BUF_STATE_DEQUEUED)
 		return;
 
 	vb->state = VB2_BUF_STATE_DEQUEUED;
-
-	/* unmap DMABUF buffer */
-	if (q->memory == VB2_MEMORY_DMABUF)
-		for (i = 0; i < vb->num_planes; ++i) {
-			if (!vb->planes[i].dbuf_mapped)
-				continue;
-			call_void_memop(vb, unmap_dmabuf, vb->planes[i].mem_priv);
-			vb->planes[i].dbuf_mapped = 0;
-		}
 }
 
 /**
@@ -1885,6 +1891,9 @@ static void __vb2_queue_cancel(struct vb2_queue *q)
 			call_void_vb_qop(vb, buf_finish, vb);
 		}
 		__vb2_dqbuf(vb);
+
+		if (q->memory == VB2_MEMORY_DMABUF)
+			__vb2_unmap_dmabuf(vb);
 	}
 }
 
-- 
2.5.5