[RFC v5 09/11] [media] vb2: add infrastructure to support out-fences

From: Gustavo Padovan
Date: Wed Nov 15 2017 - 12:13:59 EST


From: Gustavo Padovan <gustavo.padovan@xxxxxxxxxxxxx>

Add vb2_setup_out_fence() and the needed members to struct vb2_buffer.

v3:
- Do not hold yet another ref to the out_fence (Brian Starkey)

v2: - change it to reflect fd_install at DQEVENT
- add fence context for out-fences

Signed-off-by: Gustavo Padovan <gustavo.padovan@xxxxxxxxxxxxx>
---
drivers/media/v4l2-core/videobuf2-core.c | 28 ++++++++++++++++++++++++++++
include/media/videobuf2-core.h | 20 ++++++++++++++++++++
2 files changed, 48 insertions(+)

diff --git a/drivers/media/v4l2-core/videobuf2-core.c b/drivers/media/v4l2-core/videobuf2-core.c
index 26de4c80717d..8b4f0e9bcb36 100644
--- a/drivers/media/v4l2-core/videobuf2-core.c
+++ b/drivers/media/v4l2-core/videobuf2-core.c
@@ -24,8 +24,10 @@
#include <linux/freezer.h>
#include <linux/kthread.h>
#include <linux/dma-fence-array.h>
+#include <linux/sync_file.h>

#include <media/videobuf2-core.h>
+#include <media/videobuf2-fence.h>
#include <media/v4l2-mc.h>

#include <trace/events/vb2.h>
@@ -1320,6 +1322,32 @@ int vb2_core_prepare_buf(struct vb2_queue *q, unsigned int index, void *pb)
}
EXPORT_SYMBOL_GPL(vb2_core_prepare_buf);

+int vb2_setup_out_fence(struct vb2_queue *q, unsigned int index)
+{
+ struct vb2_buffer *vb;
+
+ vb = q->bufs[index];
+
+ vb->out_fence_fd = get_unused_fd_flags(O_CLOEXEC);
+
+ vb->out_fence = vb2_fence_alloc(q->out_fence_context);
+ if (!vb->out_fence) {
+ put_unused_fd(vb->out_fence_fd);
+ return -ENOMEM;
+ }
+
+ vb->sync_file = sync_file_create(vb->out_fence);
+ if (!vb->sync_file) {
+ put_unused_fd(vb->out_fence_fd);
+ dma_fence_put(vb->out_fence);
+ vb->out_fence = NULL;
+ return -ENOMEM;
+ }
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(vb2_setup_out_fence);
+
/**
* vb2_start_streaming() - Attempt to start streaming.
* @q: videobuf2 queue
diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h
index 5f48c7be7770..a9b0697bd782 100644
--- a/include/media/videobuf2-core.h
+++ b/include/media/videobuf2-core.h
@@ -259,6 +259,10 @@ struct vb2_buffer {
* using the buffer (queueing to the driver)
* fence_cb: fence callback information
* fence_cb_lock: protect callback signal/remove
+ * out_fence_fd: the out_fence_fd to be shared with userspace.
+ * out_fence: the out-fence associated with the buffer once
+ * it is queued to the driver.
+ * sync_file: the sync file to wrap the out fence
*/
enum vb2_buffer_state state;

@@ -269,6 +273,10 @@ struct vb2_buffer {
struct dma_fence_cb fence_cb;
spinlock_t fence_cb_lock;

+ int out_fence_fd;
+ struct dma_fence *out_fence;
+ struct sync_file *sync_file;
+
#ifdef CONFIG_VIDEO_ADV_DEBUG
/*
* Counters for how often these buffer-related ops are
@@ -514,6 +522,7 @@ struct vb2_buf_ops {
* @last_buffer_dequeued: used in poll() and DQBUF to immediately return if the
* last decoded buffer was already dequeued. Set for capture queues
* when a buffer with the V4L2_BUF_FLAG_LAST is dequeued.
+ * @out_fence_context: the fence context for the out fences
* @last_fence: last in-fence received. Used to keep ordering.
* @fileio: file io emulator internal data, used only if emulator is active
* @threadio: thread io internal data, used only if thread is active
@@ -569,6 +578,7 @@ struct vb2_queue {
unsigned int copy_timestamp:1;
unsigned int last_buffer_dequeued:1;

+ u64 out_fence_context;
struct dma_fence *last_fence;

struct vb2_fileio_data *fileio;
@@ -740,6 +750,16 @@ int vb2_core_create_bufs(struct vb2_queue *q, enum vb2_memory memory,
int vb2_core_prepare_buf(struct vb2_queue *q, unsigned int index, void *pb);

/**
+ * vb2_setup_out_fence() - setup new out-fence
+ * @q: The vb2_queue where to setup it
+ * @index: index of the buffer
+ *
+ * Setup the file descriptor, the fence and the sync_file for the next
+ * buffer to be queued and add everything to the tail of the q->out_fence_list.
+ */
+int vb2_setup_out_fence(struct vb2_queue *q, unsigned int index);
+
+/**
* vb2_core_qbuf() - Queue a buffer from userspace
*
* @q: videobuf2 queue
--
2.13.6