[PATCH 35/55] videobuf2: core: Add min_dma_buffers_needed field to vb2_queue

From: Benjamin Gaignard
Date: Mon Nov 27 2023 - 11:57:00 EST


'min_dma_buffers_needed' field is to clarify 'min_buffers_needed'
purpose versus 'min_reqbufs_allocation' usage.
'min_buffers_needed' is still used in few drivers so directly
rename it would be problematic.
The both will live together while fixing the drivers to use
'min_dma_buffers_needed' field instead.

Signed-off-by: Benjamin Gaignard <benjamin.gaignard@xxxxxxxxxxxxx>
---
.../media/common/videobuf2/videobuf2-core.c | 28 ++++++++++++++-----
include/media/videobuf2-core.h | 7 +++++
2 files changed, 28 insertions(+), 7 deletions(-)

diff --git a/drivers/media/common/videobuf2/videobuf2-core.c b/drivers/media/common/videobuf2/videobuf2-core.c
index c224d13b3105..a6ec55db8635 100644
--- a/drivers/media/common/videobuf2/videobuf2-core.c
+++ b/drivers/media/common/videobuf2/videobuf2-core.c
@@ -816,7 +816,7 @@ static bool verify_coherency_flags(struct vb2_queue *q, bool non_coherent_mem)
int vb2_core_reqbufs(struct vb2_queue *q, enum vb2_memory memory,
unsigned int flags, unsigned int *count)
{
- unsigned int num_buffers, allocated_buffers, num_planes = 0;
+ unsigned int num_buffers, allocated_buffers, min_reqbufs_needed, num_planes = 0;
unsigned int q_num_bufs = vb2_get_num_buffers(q);
unsigned plane_sizes[VB2_MAX_PLANES] = { };
bool non_coherent_mem = flags & V4L2_MEMORY_FLAG_NON_COHERENT;
@@ -866,7 +866,11 @@ int vb2_core_reqbufs(struct vb2_queue *q, enum vb2_memory memory,
* Make sure the requested values and current defaults are sane.
*/
num_buffers = max_t(unsigned int, *count, q->min_buffers_needed);
- num_buffers = max_t(unsigned int, num_buffers, q->min_reqbufs_allocation);
+ if (q->min_reqbufs_allocation)
+ num_buffers = max_t(unsigned int, num_buffers, q->min_reqbufs_allocation);
+ else
+ num_buffers = max_t(unsigned int, num_buffers, q->min_dma_buffers_needed + 1);
+ min_reqbufs_needed = num_buffers;
num_buffers = min_t(unsigned int, num_buffers, q->max_num_buffers);
memset(q->alloc_devs, 0, sizeof(q->alloc_devs));
/*
@@ -918,7 +922,7 @@ int vb2_core_reqbufs(struct vb2_queue *q, enum vb2_memory memory,
* There is no point in continuing if we can't allocate the minimum
* number of buffers needed by this vb2_queue.
*/
- if (allocated_buffers < q->min_buffers_needed)
+ if (allocated_buffers < min_reqbufs_needed)
ret = -ENOMEM;

/*
@@ -1654,7 +1658,7 @@ EXPORT_SYMBOL_GPL(vb2_core_prepare_buf);
* @q: videobuf2 queue
*
* Attempt to start streaming. When this function is called there must be
- * at least q->min_buffers_needed buffers queued up (i.e. the minimum
+ * at least q->min_dma_buffers_needed queued up (i.e. the minimum
* number of buffers required for the DMA engine to function). If the
* @start_streaming op fails it is supposed to return all the driver-owned
* buffers back to vb2 in state QUEUED. Check if that happened and if
@@ -1847,7 +1851,8 @@ int vb2_core_qbuf(struct vb2_queue *q, struct vb2_buffer *vb, void *pb,
* then we can finally call start_streaming().
*/
if (q->streaming && !q->start_streaming_called &&
- q->queued_count >= q->min_buffers_needed) {
+ ((q->queued_count >= q->min_buffers_needed) ||
+ (q->queued_count >= q->min_dma_buffers_needed))) {
ret = vb2_start_streaming(q);
if (ret) {
/*
@@ -2217,6 +2222,12 @@ int vb2_core_streamon(struct vb2_queue *q, unsigned int type)
return -EINVAL;
}

+ if (q_num_bufs < q->min_dma_buffers_needed) {
+ dprintk(q, 1, "need at least %u allocated buffers\n",
+ q->min_dma_buffers_needed);
+ return -EINVAL;
+ }
+
ret = call_qop(q, prepare_streaming, q);
if (ret)
return ret;
@@ -2225,7 +2236,8 @@ int vb2_core_streamon(struct vb2_queue *q, unsigned int type)
* Tell driver to start streaming provided sufficient buffers
* are available.
*/
- if (q->queued_count >= q->min_buffers_needed) {
+ if (q->queued_count >= q->min_buffers_needed &&
+ q->queued_count >= q->min_dma_buffers_needed) {
ret = vb2_start_streaming(q);
if (ret)
goto unprepare;
@@ -2505,6 +2517,7 @@ int vb2_core_queue_init(struct vb2_queue *q)
return -EINVAL;

if (WARN_ON(q->max_num_buffers > MAX_BUFFER_INDEX) ||
+ WARN_ON(q->min_dma_buffers_needed > q->max_num_buffers) ||
WARN_ON(q->min_buffers_needed > q->max_num_buffers))
return -EINVAL;

@@ -2519,7 +2532,8 @@ int vb2_core_queue_init(struct vb2_queue *q)
* in that request) will always succeed. There is no method of
* propagating an error back to userspace.
*/
- if (WARN_ON(q->supports_requests && q->min_buffers_needed))
+ if (WARN_ON(q->supports_requests &&
+ (q->min_buffers_needed || q->min_dma_buffers_needed)))
return -EINVAL;

INIT_LIST_HEAD(&q->queued_list);
diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h
index 17cacd696ab4..0bc97f28a7ea 100644
--- a/include/media/videobuf2-core.h
+++ b/include/media/videobuf2-core.h
@@ -549,10 +549,16 @@ struct vb2_buf_ops {
* @min_buffers_needed: the minimum number of buffers needed before
* @start_streaming can be called. Used when a DMA engine
* cannot be started unless at least this number of buffers
+ * have been queued into the driver. (Deprecated)
+ * @min_dma_buffers_needed: the minimum number of buffers needed before
+ * @start_streaming can be called. Used when a DMA engine
+ * cannot be started unless at least this number of buffers
* have been queued into the driver.
* @min_reqbufs_allocation: the minimum number of buffers allocated when
* calling VIDIOC_REQBUFS. Used when drivers need a to
* specify a minimum buffers allocation before setup a queue.
+ * If set to 0 then min_dma_buffers_needed + 1 value is used
+ * as minimum numbers of buffers value.
*/
/*
* Private elements (won't appear at the uAPI book):
@@ -618,6 +624,7 @@ struct vb2_queue {
u32 timestamp_flags;
gfp_t gfp_flags;
u32 min_buffers_needed;
+ u32 min_dma_buffers_needed;
u32 min_reqbufs_allocation;

struct device *alloc_devs[VB2_MAX_PLANES];
--
2.39.2