[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>

1 files changed, 15 insertions, 5 deletions

diff --git a/drivers/media/video/atmel-isi.c b/drivers/media/video/atmel-isi.c
index 7e1d7896fc6e..774715d2f84f 100644
--- a/drivers/media/video/atmel-isi.c
+++ b/drivers/media/video/atmel-isi.c
@@ -404,12 +404,13 @@ static void buffer_queue(struct vb2_buffer *vb)
 
         if (isi->active == NULL) {
                 isi->active = buf;
-                start_dma(isi, buf);
+                if (vb2_is_streaming(vb->vb2_queue))
+                        start_dma(isi, buf);
         }
         spin_unlock_irqrestore(&isi->lock, flags);
 }
 
-static int start_streaming(struct vb2_queue *vq)
+static int start_streaming(struct vb2_queue *vq, unsigned int count)
 {
         struct soc_camera_device *icd = soc_camera_from_vb2q(vq);
         struct soc_camera_host *ici = to_soc_camera_host(icd->parent);
@@ -431,17 +432,26 @@ static int start_streaming(struct vb2_queue *vq)
         ret = wait_event_interruptible(isi->vsync_wq,
                                        isi->state != ISI_STATE_IDLE);
         if (ret)
-                return ret;
+                goto err;
 
-        if (isi->state != ISI_STATE_READY)
-                return -EIO;
+        if (isi->state != ISI_STATE_READY) {
+                ret = -EIO;
+                goto err;
+        }
 
         spin_lock_irq(&isi->lock);
         isi->state = ISI_STATE_WAIT_SOF;
         isi_writel(isi, ISI_INTDIS, ISI_SR_VSYNC);
+        if (count)
+                start_dma(isi, isi->active);
         spin_unlock_irq(&isi->lock);
 
         return 0;
+err:
+        isi->active = NULL;
+        isi->sequence = 0;
+        INIT_LIST_HEAD(&isi->video_buffer_list);
+        return ret;
 }
 
 /* abort streaming and wait for last buffer */