From: Hans Verkuil <hverkuil-ci...@xs4all.nl>

Add support for tags to vb2. Besides just storing and setting
the tag this patch also adds the vb2_find_tag() function that
can be used to find a buffer with the given tag.

This function will only look at DEQUEUED and DONE buffers, i.e.
buffers that are already processed.

Signed-off-by: Hans Verkuil <hverkuil-ci...@xs4all.nl>
Reviewed-by: Paul Kocialkowski <paul.kocialkow...@bootlin.com>
Reviewed-by: Alexandre Courbot <acour...@chromium.org>
---
 .../media/common/videobuf2/videobuf2-v4l2.c   | 39 ++++++++++++++++---
 include/media/videobuf2-v4l2.h                | 21 +++++++++-
 2 files changed, 53 insertions(+), 7 deletions(-)

diff --git a/drivers/media/common/videobuf2/videobuf2-v4l2.c 
b/drivers/media/common/videobuf2/videobuf2-v4l2.c
index 1244c246d0c4..e0e31e1c67c9 100644
--- a/drivers/media/common/videobuf2/videobuf2-v4l2.c
+++ b/drivers/media/common/videobuf2/videobuf2-v4l2.c
@@ -50,7 +50,8 @@ module_param(debug, int, 0644);
                                 V4L2_BUF_FLAG_TIMESTAMP_MASK)
 /* Output buffer flags that should be passed on to the driver */
 #define V4L2_BUFFER_OUT_FLAGS  (V4L2_BUF_FLAG_PFRAME | V4L2_BUF_FLAG_BFRAME | \
-                                V4L2_BUF_FLAG_KEYFRAME | 
V4L2_BUF_FLAG_TIMECODE)
+                                V4L2_BUF_FLAG_KEYFRAME | \
+                                V4L2_BUF_FLAG_TIMECODE | V4L2_BUF_FLAG_TAG)
 
 /*
  * __verify_planes_array() - verify that the planes array passed in struct
@@ -144,7 +145,10 @@ static void __copy_timestamp(struct vb2_buffer *vb, const 
void *pb)
                 */
                if (q->copy_timestamp)
                        vb->timestamp = timeval_to_ns(&b->timestamp);
-               vbuf->flags |= b->flags & V4L2_BUF_FLAG_TIMECODE;
+               vbuf->flags |= b->flags &
+                       (V4L2_BUF_FLAG_TIMECODE | V4L2_BUF_FLAG_TAG);
+               if (b->flags & V4L2_BUF_FLAG_TAG)
+                       vbuf->tag = b->tag;
                if (b->flags & V4L2_BUF_FLAG_TIMECODE)
                        vbuf->timecode = b->timecode;
        }
@@ -194,6 +198,7 @@ static int vb2_fill_vb2_v4l2_buffer(struct vb2_buffer *vb, 
struct v4l2_buffer *b
        }
        vbuf->sequence = 0;
        vbuf->request_fd = -1;
+       vbuf->tag = 0;
 
        if (V4L2_TYPE_IS_MULTIPLANAR(b->type)) {
                switch (b->memory) {
@@ -314,12 +319,12 @@ static int vb2_fill_vb2_v4l2_buffer(struct vb2_buffer 
*vb, struct v4l2_buffer *b
 
        if (V4L2_TYPE_IS_OUTPUT(b->type)) {
                /*
-                * For output buffers mask out the timecode flag:
-                * this will be handled later in vb2_qbuf().
+                * For output buffers mask out the timecode and tag flags:
+                * these will be handled later in vb2_qbuf().
                 * The 'field' is valid metadata for this output buffer
                 * and so that needs to be copied here.
                 */
-               vbuf->flags &= ~V4L2_BUF_FLAG_TIMECODE;
+               vbuf->flags &= ~(V4L2_BUF_FLAG_TIMECODE | V4L2_BUF_FLAG_TAG);
                vbuf->field = b->field;
        } else {
                /* Zero any output buffer flags as this is a capture buffer */
@@ -460,7 +465,10 @@ static void __fill_v4l2_buffer(struct vb2_buffer *vb, void 
*pb)
        b->flags = vbuf->flags;
        b->field = vbuf->field;
        b->timestamp = ns_to_timeval(vb->timestamp);
-       b->timecode = vbuf->timecode;
+       if (b->flags & V4L2_BUF_FLAG_TAG)
+               b->tag = vbuf->tag;
+       if (b->flags & V4L2_BUF_FLAG_TIMECODE)
+               b->timecode = vbuf->timecode;
        b->sequence = vbuf->sequence;
        b->reserved2 = 0;
        b->request_fd = 0;
@@ -586,6 +594,25 @@ static const struct vb2_buf_ops v4l2_buf_ops = {
        .copy_timestamp         = __copy_timestamp,
 };
 
+int vb2_find_tag(const struct vb2_queue *q, u32 tag,
+                unsigned int start_idx)
+{
+       unsigned int i;
+
+       for (i = start_idx; i < q->num_buffers; i++) {
+               struct vb2_buffer *vb = q->bufs[i];
+               struct vb2_v4l2_buffer *vbuf = to_vb2_v4l2_buffer(vb);
+
+               if ((vb->state == VB2_BUF_STATE_DEQUEUED ||
+                    vb->state == VB2_BUF_STATE_DONE) &&
+                   (vbuf->flags & V4L2_BUF_FLAG_TAG) &&
+                   vbuf->tag == tag)
+                       return i;
+       }
+       return -1;
+}
+EXPORT_SYMBOL_GPL(vb2_find_tag);
+
 /*
  * vb2_querybuf() - query video buffer information
  * @q:         videobuf queue
diff --git a/include/media/videobuf2-v4l2.h b/include/media/videobuf2-v4l2.h
index 727855463838..c2a541af6b2c 100644
--- a/include/media/videobuf2-v4l2.h
+++ b/include/media/videobuf2-v4l2.h
@@ -31,8 +31,9 @@
  * @field:     field order of the image in the buffer, as defined by
  *             &enum v4l2_field.
  * @timecode:  frame timecode.
+ * @tag:       user specified buffer tag value.
  * @sequence:  sequence count of this frame.
- * @request_fd:        the request_fd associated with this buffer
+ * @request_fd:        the request_fd associated with this buffer.
  * @planes:    plane information (userptr/fd, length, bytesused, data_offset).
  *
  * Should contain enough information to be able to cover all the fields
@@ -44,6 +45,7 @@ struct vb2_v4l2_buffer {
        __u32                   flags;
        __u32                   field;
        struct v4l2_timecode    timecode;
+       __u32                   tag;
        __u32                   sequence;
        __s32                   request_fd;
        struct vb2_plane        planes[VB2_MAX_PLANES];
@@ -55,6 +57,23 @@ struct vb2_v4l2_buffer {
 #define to_vb2_v4l2_buffer(vb) \
        container_of(vb, struct vb2_v4l2_buffer, vb2_buf)
 
+/**
+ * vb2_find_tag() - Find buffer with given tag in the queue
+ *
+ * @q:         pointer to &struct vb2_queue with videobuf2 queue.
+ * @tag:       the tag to find. Only buffers in state DEQUEUED or DONE
+ *             are considered.
+ * @start_idx: the start index (usually 0) in the buffer array to start
+ *             searching from. Note that there may be multiple buffers
+ *             with the same tag value, so you can restart the search
+ *             by setting @start_idx to the previously found index + 1.
+ *
+ * Returns the buffer index of the buffer with the given @tag, or
+ * -1 if no buffer with @tag was found.
+ */
+int vb2_find_tag(const struct vb2_queue *q, u32 tag,
+                unsigned int start_idx);
+
 int vb2_querybuf(struct vb2_queue *q, struct v4l2_buffer *b);
 
 /**
-- 
2.19.1

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