[media] media: vb2: change queue initialization order

This patch changes the order of operations during stream on call. Now the
buffers are first queued to the driver and then the start_streaming method
is called.

This resolves the most common case when the driver needs to know buffer
addresses to enable dma engine and start streaming. Additional parameter
to start_streaming method have been added to simplify drivers code. The
driver are now obliged to check if the number of queued buffers is high
enough to enable hardware streaming. If not - it can return an error. In
such case all the buffers that have been pre-queued are invalidated.

This patch also updates all videobuf2 clients to work properly with the
changed order of operations.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
CC: Pawel Osciak <pawel@osciak.com>
CC: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
CC: Hans Verkuil <hverkuil@xs4all.nl>
CC: Tomasz Stanislawski <t.stanislaws@samsung.com>
CC: Sylwester Nawrocki <s.nawrocki@samsung.com>
CC: Kamil Debski <k.debski@samsung.com>
CC: Jonathan Corbet <corbet@lwn.net>
CC: Josh Wu <josh.wu@atmel.com>
CC: Hans de Goede <hdegoede@redhat.com>
CC: Paul Mundt <lethal@linux-sh.org>
Tested-by: Josh Wu <josh.wu@atmel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

2 files changed, 11 insertions, 13 deletions

diff --git a/drivers/media/video/s5p-tv/mixer.h b/drivers/media/video/s5p-tv/mixer.h
index e2242243f63..51ad59b3035 100644
--- a/drivers/media/video/s5p-tv/mixer.h
+++ b/drivers/media/video/s5p-tv/mixer.h
@@ -111,8 +111,6 @@ struct mxr_buffer {
 enum mxr_layer_state {
 	/** layers is not shown */
 	MXR_LAYER_IDLE = 0,
-	/** state between STREAMON and hardware start */
-	MXR_LAYER_STREAMING_START,
 	/** layer is shown */
 	MXR_LAYER_STREAMING,
 	/** state before STREAMOFF is finished */
diff --git a/drivers/media/video/s5p-tv/mixer_video.c b/drivers/media/video/s5p-tv/mixer_video.c
index 8bea0f3927f..4917e2c2b32 100644
--- a/drivers/media/video/s5p-tv/mixer_video.c
+++ b/drivers/media/video/s5p-tv/mixer_video.c
@@ -764,19 +764,10 @@ static void buf_queue(struct vb2_buffer *vb)
 	struct mxr_layer *layer = vb2_get_drv_priv(vb->vb2_queue);
 	struct mxr_device *mdev = layer->mdev;
 	unsigned long flags;
-	int must_start = 0;
 
 	spin_lock_irqsave(&layer->enq_slock, flags);
-	if (layer->state == MXR_LAYER_STREAMING_START) {
-		layer->state = MXR_LAYER_STREAMING;
-		must_start = 1;
-	}
 	list_add_tail(&buffer->list, &layer->enq_list);
 	spin_unlock_irqrestore(&layer->enq_slock, flags);
-	if (must_start) {
-		layer->ops.stream_set(layer, MXR_ENABLE);
-		mxr_streamer_get(mdev);
-	}
 
 	mxr_dbg(mdev, "queuing buffer\n");
 }
@@ -797,13 +788,19 @@ static void wait_unlock(struct vb2_queue *vq)
 	mutex_unlock(&layer->mutex);
 }
 
-static int start_streaming(struct vb2_queue *vq)
+static int start_streaming(struct vb2_queue *vq, unsigned int count)
 {
 	struct mxr_layer *layer = vb2_get_drv_priv(vq);
 	struct mxr_device *mdev = layer->mdev;
 	unsigned long flags;
 
 	mxr_dbg(mdev, "%s\n", __func__);
+
+	if (count == 0) {
+		mxr_dbg(mdev, "no output buffers queued\n");
+		return -EINVAL;
+	}
+
 	/* block any changes in output configuration */
 	mxr_output_get(mdev);
 
@@ -814,9 +811,12 @@ static int start_streaming(struct vb2_queue *vq)
 	layer->ops.format_set(layer);
 	/* enabling layer in hardware */
 	spin_lock_irqsave(&layer->enq_slock, flags);
-	layer->state = MXR_LAYER_STREAMING_START;
+	layer->state = MXR_LAYER_STREAMING;
 	spin_unlock_irqrestore(&layer->enq_slock, flags);
 
+	layer->ops.stream_set(layer, MXR_ENABLE);
+	mxr_streamer_get(mdev);
+
 	return 0;
 }