media: videobuf2: handle V4L2 buffer cache flags

Set video buffer cache management flags corresponding to V4L2 cache
flags.

Both ->prepare() and ->finish() cache management hints should be
passed during this stage (buffer preparation), because there is
no other way for user-space to tell V4L2 to avoid ->finish() cache
flush.

Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

diff --git a/drivers/media/common/videobuf2/videobuf2-v4l2.c b/drivers/media/common/videobuf2/videobuf2-v4l2.c
index eb5d5db..f138512 100644 (file)
--- a/drivers/media/common/videobuf2/videobuf2-v4l2.c
+++ b/drivers/media/common/videobuf2/videobuf2-v4l2.c
@@ -337,6 +337,53 @@ static int vb2_fill_vb2_v4l2_buffer(struct vb2_buffer *vb, struct v4l2_buffer *b
        return 0;
 }
 
+static void set_buffer_cache_hints(struct vb2_queue *q,
+                                  struct vb2_buffer *vb,
+                                  struct v4l2_buffer *b)
+{
+       /*
+        * DMA exporter should take care of cache syncs, so we can avoid
+        * explicit ->prepare()/->finish() syncs. For other ->memory types
+        * we always need ->prepare() or/and ->finish() cache sync.
+        */
+       if (q->memory == VB2_MEMORY_DMABUF) {
+               vb->need_cache_sync_on_finish = 0;
+               vb->need_cache_sync_on_prepare = 0;
+               return;
+       }
+
+       /*
+        * Cache sync/invalidation flags are set by default in order to
+        * preserve existing behaviour for old apps/drivers.
+        */
+       vb->need_cache_sync_on_prepare = 1;
+       vb->need_cache_sync_on_finish = 1;
+
+       if (!vb2_queue_allows_cache_hints(q)) {
+               /*
+                * Clear buffer cache flags if queue does not support user
+                * space hints. That's to indicate to userspace that these
+                * flags won't work.
+                */
+               b->flags &= ~V4L2_BUF_FLAG_NO_CACHE_INVALIDATE;
+               b->flags &= ~V4L2_BUF_FLAG_NO_CACHE_CLEAN;
+               return;
+       }
+
+       /*
+        * ->finish() cache sync can be avoided when queue direction is
+        * TO_DEVICE.
+        */
+       if (q->dma_dir == DMA_TO_DEVICE)
+               vb->need_cache_sync_on_finish = 0;
+
+       if (b->flags & V4L2_BUF_FLAG_NO_CACHE_INVALIDATE)
+               vb->need_cache_sync_on_finish = 0;
+
+       if (b->flags & V4L2_BUF_FLAG_NO_CACHE_CLEAN)
+               vb->need_cache_sync_on_prepare = 0;
+}
+
 static int vb2_queue_or_prepare_buf(struct vb2_queue *q, struct media_device *mdev,
                                    struct v4l2_buffer *b, bool is_prepare,
                                    struct media_request **p_req)
@@ -381,6 +428,7 @@ static int vb2_queue_or_prepare_buf(struct vb2_queue *q, struct media_device *md
        }
 
        if (!vb->prepared) {
+               set_buffer_cache_hints(q, vb, b);
                /* Copy relevant information provided by the userspace */
                memset(vbuf->planes, 0,
                       sizeof(vbuf->planes[0]) * vb->num_planes);

diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h
index 7f39d9f..ccc5c49 100644 (file)
--- a/include/media/videobuf2-core.h
+++ b/include/media/videobuf2-core.h
@@ -636,6 +636,17 @@ struct vb2_queue {
 };
 
 /**
+ * vb2_queue_allows_cache_hints() - Return true if the queue allows cache
+ * and memory consistency hints.
+ *
+ * @q:         pointer to &struct vb2_queue with videobuf2 queue
+ */
+static inline bool vb2_queue_allows_cache_hints(struct vb2_queue *q)
+{
+       return q->allow_cache_hints && q->memory == VB2_MEMORY_MMAP;
+}
+
+/**
  * vb2_plane_vaddr() - Return a kernel virtual address of a given plane.
  * @vb:                pointer to &struct vb2_buffer to which the plane in
  *             question belongs to.