4 files changed, 29 insertions, 7 deletions

diff --git a/drivers/media/video/omap3isp/isp.c b/drivers/media/video/omap3isp/isp.c
index 12d5f923e1d0..3db8583497ee 100644
--- a/drivers/media/video/omap3isp/isp.c
+++ b/drivers/media/video/omap3isp/isp.c
@@ -739,6 +739,17 @@ static int isp_pipeline_enable(struct isp_pipeline *pipe,
 	unsigned long flags;
 	int ret;
 
+	/* If the preview engine crashed it might not respond to read/write
+	 * operations on the L4 bus. This would result in a bus fault and a
+	 * kernel oops. Refuse to start streaming in that case. This check must
+	 * be performed before the loop below to avoid starting entities if the
+	 * pipeline won't start anyway (those entities would then likely fail to
+	 * stop, making the problem worse).
+	 */
+	if ((pipe->entities & isp->crashed) &
+	    (1U << isp->isp_prev.subdev.entity.id))
+		return -EIO;
+
 	spin_lock_irqsave(&pipe->lock, flags);
 	pipe->state &= ~(ISP_PIPELINE_IDLE_INPUT | ISP_PIPELINE_IDLE_OUTPUT);
 	spin_unlock_irqrestore(&pipe->lock, flags);
@@ -879,13 +890,15 @@ static int isp_pipeline_disable(struct isp_pipeline *pipe)
 
 		if (ret) {
 			dev_info(isp->dev, "Unable to stop %s\n", subdev->name);
+			/* If the entity failed to stopped, assume it has
+			 * crashed. Mark it as such, the ISP will be reset when
+			 * applications will release it.
+			 */
+			isp->crashed |= 1U << subdev->entity.id;
 			failure = -ETIMEDOUT;
 		}
 	}
 
-	if (failure < 0)
-		isp->needs_reset = true;
-
 	return failure;
 }
 
@@ -1069,6 +1082,7 @@ static int isp_reset(struct isp_device *isp)
 		udelay(1);
 	}
 
+	isp->crashed = 0;
 	return 0;
 }
 
@@ -1496,10 +1510,11 @@ void omap3isp_put(struct isp_device *isp)
 	if (--isp->ref_count == 0) {
 		isp_disable_interrupts(isp);
 		isp_save_ctx(isp);
-		if (isp->needs_reset) {
+		/* Reset the ISP if an entity has failed to stop. This is the
+		 * only way to recover from such conditions.
+		 */
+		if (isp->crashed)
 			isp_reset(isp);
-			isp->needs_reset = false;
-		}
 		isp_disable_clocks(isp);
 	}
 	mutex_unlock(&isp->isp_mutex);
diff --git a/drivers/media/video/omap3isp/isp.h b/drivers/media/video/omap3isp/isp.h
index d96603eb0d17..f8d1f100fc19 100644
--- a/drivers/media/video/omap3isp/isp.h
+++ b/drivers/media/video/omap3isp/isp.h
@@ -145,6 +145,7 @@ struct isp_platform_callback {
  * @raw_dmamask: Raw DMA mask
  * @stat_lock: Spinlock for handling statistics
  * @isp_mutex: Mutex for serializing requests to ISP.
+ * @crashed: Bitmask of crashed entities (indexed by entity ID)
  * @has_context: Context has been saved at least once and can be restored.
  * @ref_count: Reference count for handling multiple ISP requests.
  * @cam_ick: Pointer to camera interface clock structure.
@@ -184,7 +185,7 @@ struct isp_device {
 	/* ISP Obj */
 	spinlock_t stat_lock;	/* common lock for statistic drivers */
 	struct mutex isp_mutex;	/* For handling ref_count field */
-	bool needs_reset;
+	u32 crashed;
 	int has_context;
 	int ref_count;
 	unsigned int autoidle;
diff --git a/drivers/media/video/omap3isp/ispvideo.c b/drivers/media/video/omap3isp/ispvideo.c
index b02070057724..2107d99d523a 100644
--- a/drivers/media/video/omap3isp/ispvideo.c
+++ b/drivers/media/video/omap3isp/ispvideo.c
@@ -292,6 +292,7 @@ static int isp_video_validate_pipeline(struct isp_pipeline *pipe)
 	int ret;
 
 	pipe->max_rate = pipe->l3_ick;
+	pipe->entities = 0;
 
 	subdev = isp_video_remote_subdev(pipe->output, NULL);
 	if (subdev == NULL)
@@ -299,6 +300,9 @@ static int isp_video_validate_pipeline(struct isp_pipeline *pipe)
 
 	while (1) {
 		unsigned int shifter_link;
+
+		pipe->entities |= 1U << subdev->entity.id;
+
 		/* Retrieve the sink format */
 		pad = &subdev->entity.pads[0];
 		if (!(pad->flags & MEDIA_PAD_FL_SINK))
diff --git a/drivers/media/video/omap3isp/ispvideo.h b/drivers/media/video/omap3isp/ispvideo.h
index d91bdb919be0..c9187cbc3557 100644
--- a/drivers/media/video/omap3isp/ispvideo.h
+++ b/drivers/media/video/omap3isp/ispvideo.h
@@ -88,6 +88,7 @@ enum isp_pipeline_state {
 /*
  * struct isp_pipeline - An ISP hardware pipeline
  * @error: A hardware error occurred during capture
+ * @entities: Bitmask of entities in the pipeline (indexed by entity ID)
  */
 struct isp_pipeline {
 	struct media_pipeline pipe;
@@ -96,6 +97,7 @@ struct isp_pipeline {
 	enum isp_pipeline_stream_state stream_state;
 	struct isp_video *input;
 	struct isp_video *output;
+	u32 entities;
 	unsigned long l3_ick;
 	unsigned int max_rate;
 	atomic_t frame_number;