[RFC][PATCH 04/15] videobuf2: add queue memory consistency parameter

[Sergey Senozhatsky]

Preparations for future V4L2_FLAG_MEMORY_NON_CONSISTENT support.

Extend vb2_core_reqbufs() with queue memory consistency flag.
API permits queue's consistency attribute adjustment only if
the queue has no allocated buffers, not busy, and does not have
buffers waiting to be de-queued.

If user-space attempts to allocate a buffer with consistency
requirements which don't match queue's consistency model such
allocation requests will be failed.

Signed-off-by: Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx>
---
 drivers/media/common/videobuf2/videobuf2-core.c | 17 +++++++++++++----
 drivers/media/common/videobuf2/videobuf2-v4l2.c |  4 ++--
 drivers/media/dvb-core/dvb_vb2.c                |  2 +-
 include/media/videobuf2-core.h                  |  3 ++-
 4 files changed, 18 insertions(+), 8 deletions(-)

diff --git a/drivers/media/common/videobuf2/videobuf2-core.c b/drivers/media/common/videobuf2/videobuf2-core.c
index 4489744fbbd9..668c56df13f6 100644
--- a/drivers/media/common/videobuf2/videobuf2-core.c
+++ b/drivers/media/common/videobuf2/videobuf2-core.c
@@ -664,8 +664,16 @@ int vb2_verify_memory_type(struct vb2_queue *q,
 }
 EXPORT_SYMBOL(vb2_verify_memory_type);
 
+static void __set_queue_consistency(struct vb2_queue *q, bool consistent_mem)
+{
+	if (consistent_mem)
+		q->dma_attrs &= ~DMA_ATTR_NON_CONSISTENT;
+	else
+		q->dma_attrs |= DMA_ATTR_NON_CONSISTENT;
+}
+
 int vb2_core_reqbufs(struct vb2_queue *q, enum vb2_memory memory,
-		unsigned int *count)
+		bool consistent_mem, unsigned int *count)
 {
 	unsigned int num_buffers, allocated_buffers, num_planes = 0;
 	unsigned plane_sizes[VB2_MAX_PLANES] = { };
@@ -720,6 +728,7 @@ int vb2_core_reqbufs(struct vb2_queue *q, enum vb2_memory memory,
 	num_buffers = min_t(unsigned int, num_buffers, VB2_MAX_FRAME);
 	memset(q->alloc_devs, 0, sizeof(q->alloc_devs));
 	q->memory = memory;
+	__set_queue_consistency(q, consistent_mem);
 
 	/*
 	 * Ask the driver how many buffers and planes per buffer it requires.
@@ -2498,7 +2507,7 @@ static int __vb2_init_fileio(struct vb2_queue *q, int read)
 	fileio->memory = VB2_MEMORY_MMAP;
 	fileio->type = q->type;
 	q->fileio = fileio;
-	ret = vb2_core_reqbufs(q, fileio->memory, &fileio->count);
+	ret = vb2_core_reqbufs(q, fileio->memory, true, &fileio->count);
 	if (ret)
 		goto err_kfree;
 
@@ -2555,7 +2564,7 @@ static int __vb2_init_fileio(struct vb2_queue *q, int read)
 
 err_reqbufs:
 	fileio->count = 0;
-	vb2_core_reqbufs(q, fileio->memory, &fileio->count);
+	vb2_core_reqbufs(q, fileio->memory, true, &fileio->count);
 
 err_kfree:
 	q->fileio = NULL;
@@ -2575,7 +2584,7 @@ static int __vb2_cleanup_fileio(struct vb2_queue *q)
 		vb2_core_streamoff(q, q->type);
 		q->fileio = NULL;
 		fileio->count = 0;
-		vb2_core_reqbufs(q, fileio->memory, &fileio->count);
+		vb2_core_reqbufs(q, fileio->memory, true, &fileio->count);
 		kfree(fileio);
 		dprintk(3, "file io emulator closed\n");
 	}
diff --git a/drivers/media/common/videobuf2/videobuf2-v4l2.c b/drivers/media/common/videobuf2/videobuf2-v4l2.c
index 2fccfe2a57f8..f1e88c9398c7 100644
--- a/drivers/media/common/videobuf2/videobuf2-v4l2.c
+++ b/drivers/media/common/videobuf2/videobuf2-v4l2.c
@@ -695,7 +695,7 @@ int vb2_reqbufs(struct vb2_queue *q, struct v4l2_requestbuffers *req)
 	int ret = vb2_verify_memory_type(q, req->memory, req->type);
 
 	fill_buf_caps(q, &req->capabilities);
-	return ret ? ret : vb2_core_reqbufs(q, req->memory, &req->count);
+	return ret ? ret : vb2_core_reqbufs(q, req->memory, true, &req->count);
 }
 EXPORT_SYMBOL_GPL(vb2_reqbufs);
 
@@ -945,7 +945,7 @@ int vb2_ioctl_reqbufs(struct file *file, void *priv,
 		return res;
 	if (vb2_queue_is_busy(vdev, file))
 		return -EBUSY;
-	res = vb2_core_reqbufs(vdev->queue, p->memory, &p->count);
+	res = vb2_core_reqbufs(vdev->queue, p->memory, true, &p->count);
 	/* If count == 0, then the owner has released all buffers and he
 	   is no longer owner of the queue. Otherwise we have a new owner. */
 	if (res == 0)
diff --git a/drivers/media/dvb-core/dvb_vb2.c b/drivers/media/dvb-core/dvb_vb2.c
index 6974f1731529..e60063652164 100644
--- a/drivers/media/dvb-core/dvb_vb2.c
+++ b/drivers/media/dvb-core/dvb_vb2.c
@@ -342,7 +342,7 @@ int dvb_vb2_reqbufs(struct dvb_vb2_ctx *ctx, struct dmx_requestbuffers *req)
 
 	ctx->buf_siz = req->size;
 	ctx->buf_cnt = req->count;
-	ret = vb2_core_reqbufs(&ctx->vb_q, VB2_MEMORY_MMAP, &req->count);
+	ret = vb2_core_reqbufs(&ctx->vb_q, VB2_MEMORY_MMAP, true, &req->count);
 	if (ret) {
 		ctx->state = DVB_VB2_STATE_NONE;
 		dprintk(1, "[%s] count=%d size=%d errno=%d\n", ctx->name,
diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h
index 026004180440..810af5cf5742 100644
--- a/include/media/videobuf2-core.h
+++ b/include/media/videobuf2-core.h
@@ -726,6 +726,7 @@ void vb2_core_querybuf(struct vb2_queue *q, unsigned int index, void *pb);
  * vb2_core_reqbufs() - Initiate streaming.
  * @q:		pointer to &struct vb2_queue with videobuf2 queue.
  * @memory:	memory type, as defined by &enum vb2_memory.
+ * @consistent_mem:	memory consistency model.
  * @count:	requested buffer count.
  *
  * Videobuf2 core helper to implement VIDIOC_REQBUF() operation. It is called
@@ -750,7 +751,7 @@ void vb2_core_querybuf(struct vb2_queue *q, unsigned int index, void *pb);
  * Return: returns zero on success; an error code otherwise.
  */
 int vb2_core_reqbufs(struct vb2_queue *q, enum vb2_memory memory,
-		unsigned int *count);
+		bool consistent_mem, unsigned int *count);
 
 /**
  * vb2_core_create_bufs() - Allocate buffers and any required auxiliary structs
-- 
2.24.1.735.g03f4e72817-goog