[PATCH 1/7] media: atmel: atmel-isc: add safe checks and fixed wrong ISC state in error case

[<Eugen.Hristev@xxxxxxxxxxxxx>]

From: Eugen Hristev <eugen.hristev@xxxxxxxxxxxxx>

This adds safety checks on some scenarios:
- start streaming but streaming is already started
- start streaming but no buffer in the dma queue
- spin lock is not released in error scenario
- no frame is configured but dma is requested to start
- configure ISC may have been called without need, before checking if buffer is
ok.

Signed-off-by: Eugen Hristev <eugen.hristev@xxxxxxxxxxxxx>
---
 drivers/media/platform/atmel/atmel-isc.c | 32 +++++++++++++++++++++++++++-----
 1 file changed, 27 insertions(+), 5 deletions(-)

diff --git a/drivers/media/platform/atmel/atmel-isc.c b/drivers/media/platform/atmel/atmel-isc.c
index a10db16..3c19761 100644
--- a/drivers/media/platform/atmel/atmel-isc.c
+++ b/drivers/media/platform/atmel/atmel-isc.c
@@ -722,6 +722,11 @@ static void isc_start_dma(struct isc_device *isc)
 	u32 dctrl_dview;
 	dma_addr_t addr0;
 
+	if (!isc->cur_frm) {
+		v4l2_err(&isc->v4l2_dev, "Video buffer not available\n");
+		return;
+	}
+
 	addr0 = vb2_dma_contig_plane_dma_addr(&isc->cur_frm->vb.vb2_buf, 0);
 	regmap_write(regmap, ISC_DAD0, addr0);
 
@@ -886,6 +891,9 @@ static int isc_start_streaming(struct vb2_queue *vq, unsigned int count)
 	unsigned long flags;
 	int ret;
 
+	if (vb2_is_streaming(&isc->vb2_vidq))
+		return -EBUSY;
+
 	/* Enable stream on the sub device */
 	ret = v4l2_subdev_call(isc->current_subdev->sd, video, s_stream, 1);
 	if (ret && ret != -ENOIOCTLCMD) {
@@ -896,6 +904,20 @@ static int isc_start_streaming(struct vb2_queue *vq, unsigned int count)
 
 	pm_runtime_get_sync(isc->dev);
 
+	spin_lock_irqsave(&isc->dma_queue_lock, flags);
+
+	isc->sequence = 0;
+	isc->stop = false;
+	reinit_completion(&isc->comp);
+
+	if (list_empty(&isc->dma_queue)) {
+		v4l2_err(&isc->v4l2_dev, "dma queue empty\n");
+		ret = -EINVAL;
+		goto err_configure_unlock;
+	}
+
+	spin_unlock_irqrestore(&isc->dma_queue_lock, flags);
+
 	ret = isc_configure(isc);
 	if (unlikely(ret))
 		goto err_configure;
@@ -905,10 +927,6 @@ static int isc_start_streaming(struct vb2_queue *vq, unsigned int count)
 
 	spin_lock_irqsave(&isc->dma_queue_lock, flags);
 
-	isc->sequence = 0;
-	isc->stop = false;
-	reinit_completion(&isc->comp);
-
 	isc->cur_frm = list_first_entry(&isc->dma_queue,
 					struct isc_buffer, list);
 	list_del(&isc->cur_frm->list);
@@ -919,8 +937,11 @@ static int isc_start_streaming(struct vb2_queue *vq, unsigned int count)
 
 	return 0;
 
+err_configure_unlock:
+	spin_unlock_irqrestore(&isc->dma_queue_lock, flags);
+
 err_configure:
-	pm_runtime_put_sync(isc->dev);
+	isc->stop = true;
 
 	v4l2_subdev_call(isc->current_subdev->sd, video, s_stream, 0);
 
@@ -931,6 +952,7 @@ static int isc_start_streaming(struct vb2_queue *vq, unsigned int count)
 	INIT_LIST_HEAD(&isc->dma_queue);
 	spin_unlock_irqrestore(&isc->dma_queue_lock, flags);
 
+	pm_runtime_put_sync(isc->dev);
 	return ret;
 }
 
-- 
2.7.4