For mem2mem devices we have to make sure that v4l2_m2m_try_schedule()
is called whenever a request is queued.

We do that by creating a vb2_m2m_request_queue() helper that should
be used instead of the 'normal' vb2_request_queue() helper. The m2m
helper function will call v4l2_m2m_try_schedule() as needed.

In addition we also avoid calling v4l2_m2m_try_schedule() when preparing
or queueing a buffer for a request since that is no longer needed.
Instead this helper function will do that when the request is actually
queued.

Signed-off-by: Hans Verkuil <hans.verk...@cisco.com>
---
I realized that is it important that buffers are queued last when processing a
request. Queuing a buffer is what triggers the processing of the request, so
all non-buffer information must be in place before you can queue buffers.

This v16.1 does just that.
---
 drivers/media/v4l2-core/v4l2-mem2mem.c | 59 ++++++++++++++++++++++----
 include/media/v4l2-mem2mem.h           |  4 ++
 2 files changed, 55 insertions(+), 8 deletions(-)

diff --git a/drivers/media/v4l2-core/v4l2-mem2mem.c 
b/drivers/media/v4l2-core/v4l2-mem2mem.c
index 114d50cf22c5..79e1d5e8b371 100644
--- a/drivers/media/v4l2-core/v4l2-mem2mem.c
+++ b/drivers/media/v4l2-core/v4l2-mem2mem.c
@@ -325,7 +325,7 @@ static void v4l2_m2m_cancel_job(struct v4l2_m2m_ctx 
*m2m_ctx)
        if (m2m_ctx->job_flags & TRANS_RUNNING) {
                spin_unlock_irqrestore(&m2m_dev->job_spinlock, flags);
                m2m_dev->m2m_ops->job_abort(m2m_ctx->priv);
-               dprintk("m2m_ctx %p running, will wait to complete", m2m_ctx);
+               dprintk("m2m_ctx %p running, will wait to complete\n", m2m_ctx);
                wait_event(m2m_ctx->finished,
                                !(m2m_ctx->job_flags & TRANS_RUNNING));
        } else if (m2m_ctx->job_flags & TRANS_QUEUED) {
@@ -416,8 +416,14 @@ int v4l2_m2m_qbuf(struct file *file, struct v4l2_m2m_ctx 
*m2m_ctx,
        int ret;

        vq = v4l2_m2m_get_vq(m2m_ctx, buf->type);
+       if (!V4L2_TYPE_IS_OUTPUT(vq->type) &&
+           (buf->flags & V4L2_BUF_FLAG_REQUEST_FD)) {
+               dprintk("%s: requests cannot be used with capture buffers\n",
+                       __func__);
+               return -EPERM;
+       }
        ret = vb2_qbuf(vq, vdev->v4l2_dev->mdev, buf);
-       if (!ret)
+       if (!ret && !(buf->flags & V4L2_BUF_FLAG_IN_REQUEST))
                v4l2_m2m_try_schedule(m2m_ctx);

        return ret;
@@ -439,14 +445,9 @@ int v4l2_m2m_prepare_buf(struct file *file, struct 
v4l2_m2m_ctx *m2m_ctx,
 {
        struct video_device *vdev = video_devdata(file);
        struct vb2_queue *vq;
-       int ret;

        vq = v4l2_m2m_get_vq(m2m_ctx, buf->type);
-       ret = vb2_prepare_buf(vq, vdev->v4l2_dev->mdev, buf);
-       if (!ret)
-               v4l2_m2m_try_schedule(m2m_ctx);
-
-       return ret;
+       return vb2_prepare_buf(vq, vdev->v4l2_dev->mdev, buf);
 }
 EXPORT_SYMBOL_GPL(v4l2_m2m_prepare_buf);

@@ -891,6 +892,48 @@ void v4l2_m2m_buf_queue(struct v4l2_m2m_ctx *m2m_ctx,
 }
 EXPORT_SYMBOL_GPL(v4l2_m2m_buf_queue);

+void vb2_m2m_request_queue(struct media_request *req)
+{
+       struct media_request_object *obj, *obj_safe;
+       struct v4l2_m2m_ctx *m2m_ctx = NULL;
+
+       /* Queue all non-buffer objects */
+       list_for_each_entry_safe(obj, obj_safe, &req->objects, list)
+               if (obj->ops->queue && !vb2_request_object_is_buffer(obj))
+                       obj->ops->queue(obj);
+
+       /* Queue all buffer objects */
+       list_for_each_entry_safe(obj, obj_safe, &req->objects, list) {
+               struct v4l2_m2m_ctx *m2m_ctx_obj;
+               struct vb2_buffer *vb;
+
+               if (!obj->ops->queue || !vb2_request_object_is_buffer(obj))
+                       continue;
+
+               /* Sanity checks */
+               vb = container_of(obj, struct vb2_buffer, req_obj);
+               WARN_ON(!V4L2_TYPE_IS_OUTPUT(vb->vb2_queue->type));
+               m2m_ctx_obj = container_of(vb->vb2_queue,
+                                          struct v4l2_m2m_ctx,
+                                          out_q_ctx.q);
+               WARN_ON(m2m_ctx && m2m_ctx_obj != m2m_ctx);
+               m2m_ctx = m2m_ctx_obj;
+
+               /*
+                * The buffer we queue here can in theory be immediately
+                * unbound, hence the use of list_for_each_entry_safe()
+                * above and why we call the queue op last.
+                */
+               obj->ops->queue(obj);
+       }
+
+       WARN_ON(!m2m_ctx);
+
+       if (m2m_ctx)
+               v4l2_m2m_try_schedule(m2m_ctx);
+}
+EXPORT_SYMBOL_GPL(vb2_m2m_request_queue);
+
 /* Videobuf2 ioctl helpers */

 int v4l2_m2m_ioctl_reqbufs(struct file *file, void *priv,
diff --git a/include/media/v4l2-mem2mem.h b/include/media/v4l2-mem2mem.h
index af48b1eca025..2807e7c466ce 100644
--- a/include/media/v4l2-mem2mem.h
+++ b/include/media/v4l2-mem2mem.h
@@ -593,6 +593,10 @@ v4l2_m2m_dst_buf_remove_by_idx(struct v4l2_m2m_ctx 
*m2m_ctx, unsigned int idx)
        return v4l2_m2m_buf_remove_by_idx(&m2m_ctx->cap_q_ctx, idx);
 }

+/* v4l2 request helper */
+
+void vb2_m2m_request_queue(struct media_request *req);
+
 /* v4l2 ioctl helpers */

 int v4l2_m2m_ioctl_reqbufs(struct file *file, void *priv,
-- 
2.18.0

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