[PATCH 14/20] mx_emmaprp: Implement wait_prepare and wait_finish

[Ezequiel Garcia]

This driver is currently specifying a video_device lock,
which means it is protecting all the ioctls (including
queue ioctls) with a single mutex.

It's therefore straightforward to implement wait_prepare
and wait_finish, by explicitly setting the vb2_queue lock.

Having these callbacks releases the queue lock while blocking,
which improves latency by allowing for example streamoff
or qbuf operations while waiting in dqbuf.

Signed-off-by: Ezequiel Garcia <ezequ...@collabora.com>
---
 drivers/media/platform/mx2_emmaprp.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/media/platform/mx2_emmaprp.c 
b/drivers/media/platform/mx2_emmaprp.c
index 5a8eff60e95f..7f9b356e7cc7 100644
--- a/drivers/media/platform/mx2_emmaprp.c
+++ b/drivers/media/platform/mx2_emmaprp.c
@@ -747,6 +747,8 @@ static const struct vb2_ops emmaprp_qops = {
        .queue_setup     = emmaprp_queue_setup,
        .buf_prepare     = emmaprp_buf_prepare,
        .buf_queue       = emmaprp_buf_queue,
+       .wait_prepare    = vb2_ops_wait_prepare,
+       .wait_finish     = vb2_ops_wait_finish,
 };
 
 static int queue_init(void *priv, struct vb2_queue *src_vq,
@@ -763,6 +765,7 @@ static int queue_init(void *priv, struct vb2_queue *src_vq,
        src_vq->mem_ops = &vb2_dma_contig_memops;
        src_vq->timestamp_flags = V4L2_BUF_FLAG_TIMESTAMP_COPY;
        src_vq->dev = ctx->dev->v4l2_dev.dev;
+       src_vq->lock = &ctx->dev->dev_mutex;
 
        ret = vb2_queue_init(src_vq);
        if (ret)
@@ -776,6 +779,7 @@ static int queue_init(void *priv, struct vb2_queue *src_vq,
        dst_vq->mem_ops = &vb2_dma_contig_memops;
        dst_vq->timestamp_flags = V4L2_BUF_FLAG_TIMESTAMP_COPY;
        dst_vq->dev = ctx->dev->v4l2_dev.dev;
+       dst_vq->lock = &ctx->dev->dev_mutex;
 
        return vb2_queue_init(dst_vq);
 }
-- 
2.16.3