[PATCH v5 0/3] DCMI bridge support

[PATCH v5 0/3] DCMI bridge support

[Hugues Fruchet]

This patch serie allows to connect non-parallel camera sensor to
DCMI thanks to a bridge connected in between such as STMIPID02 [1].

Media controller support is introduced first, then support of
several sub-devices within pipeline with dynamic linking
between them.
In order to keep backward compatibility with applications
relying on V4L2 interface only, format set on video node
is propagated to all sub-devices connected to camera interface.

[1] https://www.spinics.net/lists/devicetree/msg278002.html

===========
= history =
===========
version 5:
  - Remove remaining Change-Id
  - Add Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>

version 4:
  - Also drop subdev nodes registry as suggested by Hans:
    https://www.spinics.net/lists/arm-kernel/msg743375.html

version 3:
  - Drop media device registry to not expose media controller
    interface to userspace as per Laurent' suggestion:
    https://www.spinics.net/lists/linux-media/msg153417.html
  - Prefer "source" instead of "sensor" and keep it in 
    dcmi_graph_entity struct, move asd as first member
    of struct as per Sakari' suggestion:
    https://www.spinics.net/lists/linux-media/msg153119.html
  - Drop dcmi_graph_deinit() as per Sakari' suggestion:
    https://www.spinics.net/lists/linux-media/msg153417.html

version 2:
  - Fix bus_info not consistent between media and V4L:
    https://www.spinics.net/lists/arm-kernel/msg717676.html
  - Propagation of format set on video node to the sub-devices
    chain connected on camera interface

version 1:
  - Initial submission

Hugues Fruchet (3):
  media: stm32-dcmi: improve sensor subdev naming
  media: stm32-dcmi: add media controller support
  media: stm32-dcmi: add support of several sub-devices

 drivers/media/platform/Kconfig            |   2 +-
 drivers/media/platform/stm32/stm32-dcmi.c | 283 +++++++++++++++++++++++++-----
 2 files changed, 236 insertions(+), 49 deletions(-)

-- 
2.7.4

[PATCH v5 1/3] media: stm32-dcmi: improve sensor subdev naming

[Hugues Fruchet]

Rename "subdev" entity struct field to "source"
to prepare for several subdev support.
Move asd field on top of entity struct.

Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Hugues Fruchet <hugues.fruchet@st.com>
---
 drivers/media/platform/stm32/stm32-dcmi.c | 46 +++++++++++++++----------------
 1 file changed, 23 insertions(+), 23 deletions(-)

diff --git a/drivers/media/platform/stm32/stm32-dcmi.c b/drivers/media/platform/stm32/stm32-dcmi.c
index b9dad0a..b462f71 100644
--- a/drivers/media/platform/stm32/stm32-dcmi.c
+++ b/drivers/media/platform/stm32/stm32-dcmi.c
@@ -100,10 +100,10 @@ enum state {
 #define OVERRUN_ERROR_THRESHOLD	3
 
 struct dcmi_graph_entity {
-	struct device_node *node;
-
 	struct v4l2_async_subdev asd;
-	struct v4l2_subdev *subdev;
+
+	struct device_node *remote_node;
+	struct v4l2_subdev *source;
 };
 
 struct dcmi_format {
@@ -595,7 +595,7 @@ static int dcmi_start_streaming(struct vb2_queue *vq, unsigned int count)
 	}
 
 	/* Enable stream on the sub device */
-	ret = v4l2_subdev_call(dcmi->entity.subdev, video, s_stream, 1);
+	ret = v4l2_subdev_call(dcmi->entity.source, video, s_stream, 1);
 	if (ret && ret != -ENOIOCTLCMD) {
 		dev_err(dcmi->dev, "%s: Failed to start streaming, subdev streamon error",
 			__func__);
@@ -685,7 +685,7 @@ static int dcmi_start_streaming(struct vb2_queue *vq, unsigned int count)
 	return 0;
 
 err_subdev_streamoff:
-	v4l2_subdev_call(dcmi->entity.subdev, video, s_stream, 0);
+	v4l2_subdev_call(dcmi->entity.source, video, s_stream, 0);
 
 err_pm_put:
 	pm_runtime_put(dcmi->dev);
@@ -713,7 +713,7 @@ static void dcmi_stop_streaming(struct vb2_queue *vq)
 	int ret;
 
 	/* Disable stream on the sub device */
-	ret = v4l2_subdev_call(dcmi->entity.subdev, video, s_stream, 0);
+	ret = v4l2_subdev_call(dcmi->entity.source, video, s_stream, 0);
 	if (ret && ret != -ENOIOCTLCMD)
 		dev_err(dcmi->dev, "%s: Failed to stop streaming, subdev streamoff error (%d)\n",
 			__func__, ret);
@@ -857,7 +857,7 @@ static int dcmi_try_fmt(struct stm32_dcmi *dcmi, struct v4l2_format *f,
 	}
 
 	v4l2_fill_mbus_format(&format.format, pix, sd_fmt->mbus_code);
-	ret = v4l2_subdev_call(dcmi->entity.subdev, pad, set_fmt,
+	ret = v4l2_subdev_call(dcmi->entity.source, pad, set_fmt,
 			       &pad_cfg, &format);
 	if (ret < 0)
 		return ret;
@@ -934,7 +934,7 @@ static int dcmi_set_fmt(struct stm32_dcmi *dcmi, struct v4l2_format *f)
 	mf->width = sd_framesize.width;
 	mf->height = sd_framesize.height;
 
-	ret = v4l2_subdev_call(dcmi->entity.subdev, pad,
+	ret = v4l2_subdev_call(dcmi->entity.source, pad,
 			       set_fmt, NULL, &format);
 	if (ret < 0)
 		return ret;
@@ -991,7 +991,7 @@ static int dcmi_get_sensor_format(struct stm32_dcmi *dcmi,
 	};
 	int ret;
 
-	ret = v4l2_subdev_call(dcmi->entity.subdev, pad, get_fmt, NULL, &fmt);
+	ret = v4l2_subdev_call(dcmi->entity.source, pad, get_fmt, NULL, &fmt);
 	if (ret)
 		return ret;
 
@@ -1020,7 +1020,7 @@ static int dcmi_set_sensor_format(struct stm32_dcmi *dcmi,
 	}
 
 	v4l2_fill_mbus_format(&format.format, pix, sd_fmt->mbus_code);
-	ret = v4l2_subdev_call(dcmi->entity.subdev, pad, set_fmt,
+	ret = v4l2_subdev_call(dcmi->entity.source, pad, set_fmt,
 			       &pad_cfg, &format);
 	if (ret < 0)
 		return ret;
@@ -1043,7 +1043,7 @@ static int dcmi_get_sensor_bounds(struct stm32_dcmi *dcmi,
 	/*
 	 * Get sensor bounds first
 	 */
-	ret = v4l2_subdev_call(dcmi->entity.subdev, pad, get_selection,
+	ret = v4l2_subdev_call(dcmi->entity.source, pad, get_selection,
 			       NULL, &bounds);
 	if (!ret)
 		*r = bounds.r;
@@ -1224,7 +1224,7 @@ static int dcmi_enum_framesizes(struct file *file, void *fh,
 
 	fse.code = sd_fmt->mbus_code;
 
-	ret = v4l2_subdev_call(dcmi->entity.subdev, pad, enum_frame_size,
+	ret = v4l2_subdev_call(dcmi->entity.source, pad, enum_frame_size,
 			       NULL, &fse);
 	if (ret)
 		return ret;
@@ -1241,7 +1241,7 @@ static int dcmi_g_parm(struct file *file, void *priv,
 {
 	struct stm32_dcmi *dcmi = video_drvdata(file);
 
-	return v4l2_g_parm_cap(video_devdata(file), dcmi->entity.subdev, p);
+	return v4l2_g_parm_cap(video_devdata(file), dcmi->entity.source, p);
 }
 
 static int dcmi_s_parm(struct file *file, void *priv,
@@ -1249,7 +1249,7 @@ static int dcmi_s_parm(struct file *file, void *priv,
 {
 	struct stm32_dcmi *dcmi = video_drvdata(file);
 
-	return v4l2_s_parm_cap(video_devdata(file), dcmi->entity.subdev, p);
+	return v4l2_s_parm_cap(video_devdata(file), dcmi->entity.source, p);
 }
 
 static int dcmi_enum_frameintervals(struct file *file, void *fh,
@@ -1271,7 +1271,7 @@ static int dcmi_enum_frameintervals(struct file *file, void *fh,
 
 	fie.code = sd_fmt->mbus_code;
 
-	ret = v4l2_subdev_call(dcmi->entity.subdev, pad,
+	ret = v4l2_subdev_call(dcmi->entity.source, pad,
 			       enum_frame_interval, NULL, &fie);
 	if (ret)
 		return ret;
@@ -1291,7 +1291,7 @@ MODULE_DEVICE_TABLE(of, stm32_dcmi_of_match);
 static int dcmi_open(struct file *file)
 {
 	struct stm32_dcmi *dcmi = video_drvdata(file);
-	struct v4l2_subdev *sd = dcmi->entity.subdev;
+	struct v4l2_subdev *sd = dcmi->entity.source;
 	int ret;
 
 	if (mutex_lock_interruptible(&dcmi->lock))
@@ -1322,7 +1322,7 @@ static int dcmi_open(struct file *file)
 static int dcmi_release(struct file *file)
 {
 	struct stm32_dcmi *dcmi = video_drvdata(file);
-	struct v4l2_subdev *sd = dcmi->entity.subdev;
+	struct v4l2_subdev *sd = dcmi->entity.source;
 	bool fh_singular;
 	int ret;
 
@@ -1433,7 +1433,7 @@ static int dcmi_formats_init(struct stm32_dcmi *dcmi)
 {
 	const struct dcmi_format *sd_fmts[ARRAY_SIZE(dcmi_formats)];
 	unsigned int num_fmts = 0, i, j;
-	struct v4l2_subdev *subdev = dcmi->entity.subdev;
+	struct v4l2_subdev *subdev = dcmi->entity.source;
 	struct v4l2_subdev_mbus_code_enum mbus_code = {
 		.which = V4L2_SUBDEV_FORMAT_ACTIVE,
 	};
@@ -1479,7 +1479,7 @@ static int dcmi_formats_init(struct stm32_dcmi *dcmi)
 static int dcmi_framesizes_init(struct stm32_dcmi *dcmi)
 {
 	unsigned int num_fsize = 0;
-	struct v4l2_subdev *subdev = dcmi->entity.subdev;
+	struct v4l2_subdev *subdev = dcmi->entity.source;
 	struct v4l2_subdev_frame_size_enum fse = {
 		.which = V4L2_SUBDEV_FORMAT_ACTIVE,
 		.code = dcmi->sd_format->mbus_code,
@@ -1526,7 +1526,7 @@ static int dcmi_graph_notify_complete(struct v4l2_async_notifier *notifier)
 	struct stm32_dcmi *dcmi = notifier_to_dcmi(notifier);
 	int ret;
 
-	dcmi->vdev->ctrl_handler = dcmi->entity.subdev->ctrl_handler;
+	dcmi->vdev->ctrl_handler = dcmi->entity.source->ctrl_handler;
 	ret = dcmi_formats_init(dcmi);
 	if (ret) {
 		dev_err(dcmi->dev, "No supported mediabus format found\n");
@@ -1582,7 +1582,7 @@ static int dcmi_graph_notify_bound(struct v4l2_async_notifier *notifier,
 
 	dev_dbg(dcmi->dev, "Subdev %s bound\n", subdev->name);
 
-	dcmi->entity.subdev = subdev;
+	dcmi->entity.source = subdev;
 
 	return 0;
 }
@@ -1608,7 +1608,7 @@ static int dcmi_graph_parse(struct stm32_dcmi *dcmi, struct device_node *node)
 		return -EINVAL;
 
 	/* Remote node to connect */
-	dcmi->entity.node = remote;
+	dcmi->entity.remote_node = remote;
 	dcmi->entity.asd.match_type = V4L2_ASYNC_MATCH_FWNODE;
 	dcmi->entity.asd.match.fwnode = of_fwnode_handle(remote);
 	return 0;
@@ -1631,7 +1631,7 @@ static int dcmi_graph_init(struct stm32_dcmi *dcmi)
 					     &dcmi->entity.asd);
 	if (ret) {
 		dev_err(dcmi->dev, "Failed to add subdev notifier\n");
-		of_node_put(dcmi->entity.node);
+		of_node_put(dcmi->entity.remote_node);
 		return ret;
 	}
 
-- 
2.7.4

[PATCH v5 2/3] media: stm32-dcmi: add media controller support

[Hugues Fruchet]

Add media controller support to dcmi in order
to walk within remote subdevices pipeline.

Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Hugues Fruchet <hugues.fruchet@st.com>
---
 drivers/media/platform/Kconfig            |  2 +-
 drivers/media/platform/stm32/stm32-dcmi.c | 52 ++++++++++++++++++++++++-------
 2 files changed, 41 insertions(+), 13 deletions(-)

diff --git a/drivers/media/platform/Kconfig b/drivers/media/platform/Kconfig
index 8a19654..de7e21f 100644
--- a/drivers/media/platform/Kconfig
+++ b/drivers/media/platform/Kconfig
@@ -121,7 +121,7 @@ config VIDEO_S3C_CAMIF
 
 config VIDEO_STM32_DCMI
 	tristate "STM32 Digital Camera Memory Interface (DCMI) support"
-	depends on VIDEO_V4L2 && OF
+	depends on VIDEO_V4L2 && OF && MEDIA_CONTROLLER
 	depends on ARCH_STM32 || COMPILE_TEST
 	select VIDEOBUF2_DMA_CONTIG
 	select V4L2_FWNODE
diff --git a/drivers/media/platform/stm32/stm32-dcmi.c b/drivers/media/platform/stm32/stm32-dcmi.c
index b462f71..6f37617 100644
--- a/drivers/media/platform/stm32/stm32-dcmi.c
+++ b/drivers/media/platform/stm32/stm32-dcmi.c
@@ -169,6 +169,9 @@ struct stm32_dcmi {
 
 	/* Ensure DMA operations atomicity */
 	struct mutex			dma_lock;
+
+	struct media_device		mdev;
+	struct media_pad		vid_cap_pad;
 };
 
 static inline struct stm32_dcmi *notifier_to_dcmi(struct v4l2_async_notifier *n)
@@ -1551,14 +1554,6 @@ static int dcmi_graph_notify_complete(struct v4l2_async_notifier *notifier)
 		return ret;
 	}
 
-	ret = video_register_device(dcmi->vdev, VFL_TYPE_GRABBER, -1);
-	if (ret) {
-		dev_err(dcmi->dev, "Failed to register video device\n");
-		return ret;
-	}
-
-	dev_dbg(dcmi->dev, "Device registered as %s\n",
-		video_device_node_name(dcmi->vdev));
 	return 0;
 }
 
@@ -1751,10 +1746,19 @@ static int dcmi_probe(struct platform_device *pdev)
 
 	q = &dcmi->queue;
 
+	dcmi->v4l2_dev.mdev = &dcmi->mdev;
+
+	/* Initialize media device */
+	strscpy(dcmi->mdev.model, DRV_NAME, sizeof(dcmi->mdev.model));
+	snprintf(dcmi->mdev.bus_info, sizeof(dcmi->mdev.bus_info),
+		 "platform:%s", DRV_NAME);
+	dcmi->mdev.dev = &pdev->dev;
+	media_device_init(&dcmi->mdev);
+
 	/* Initialize the top-level structure */
 	ret = v4l2_device_register(&pdev->dev, &dcmi->v4l2_dev);
 	if (ret)
-		goto err_dma_release;
+		goto err_media_device_cleanup;
 
 	dcmi->vdev = video_device_alloc();
 	if (!dcmi->vdev) {
@@ -1774,6 +1778,25 @@ static int dcmi_probe(struct platform_device *pdev)
 				  V4L2_CAP_READWRITE;
 	video_set_drvdata(dcmi->vdev, dcmi);
 
+	/* Media entity pads */
+	dcmi->vid_cap_pad.flags = MEDIA_PAD_FL_SINK;
+	ret = media_entity_pads_init(&dcmi->vdev->entity,
+				     1, &dcmi->vid_cap_pad);
+	if (ret) {
+		dev_err(dcmi->dev, "Failed to init media entity pad\n");
+		goto err_device_release;
+	}
+	dcmi->vdev->entity.flags |= MEDIA_ENT_FL_DEFAULT;
+
+	ret = video_register_device(dcmi->vdev, VFL_TYPE_GRABBER, -1);
+	if (ret) {
+		dev_err(dcmi->dev, "Failed to register video device\n");
+		goto err_media_entity_cleanup;
+	}
+
+	dev_dbg(dcmi->dev, "Device registered as %s\n",
+		video_device_node_name(dcmi->vdev));
+
 	/* Buffer queue */
 	q->type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
 	q->io_modes = VB2_MMAP | VB2_READ | VB2_DMABUF;
@@ -1789,12 +1812,12 @@ static int dcmi_probe(struct platform_device *pdev)
 	ret = vb2_queue_init(q);
 	if (ret < 0) {
 		dev_err(&pdev->dev, "Failed to initialize vb2 queue\n");
-		goto err_device_release;
+		goto err_media_entity_cleanup;
 	}
 
 	ret = dcmi_graph_init(dcmi);
 	if (ret < 0)
-		goto err_device_release;
+		goto err_media_entity_cleanup;
 
 	/* Reset device */
 	ret = reset_control_assert(dcmi->rstc);
@@ -1821,11 +1844,14 @@ static int dcmi_probe(struct platform_device *pdev)
 
 err_cleanup:
 	v4l2_async_notifier_cleanup(&dcmi->notifier);
+err_media_entity_cleanup:
+	media_entity_cleanup(&dcmi->vdev->entity);
 err_device_release:
 	video_device_release(dcmi->vdev);
 err_device_unregister:
 	v4l2_device_unregister(&dcmi->v4l2_dev);
-err_dma_release:
+err_media_device_cleanup:
+	media_device_cleanup(&dcmi->mdev);
 	dma_release_channel(dcmi->dma_chan);
 
 	return ret;
@@ -1839,7 +1865,9 @@ static int dcmi_remove(struct platform_device *pdev)
 
 	v4l2_async_notifier_unregister(&dcmi->notifier);
 	v4l2_async_notifier_cleanup(&dcmi->notifier);
+	media_entity_cleanup(&dcmi->vdev->entity);
 	v4l2_device_unregister(&dcmi->v4l2_dev);
+	media_device_cleanup(&dcmi->mdev);
 
 	dma_release_channel(dcmi->dma_chan);
 
-- 
2.7.4

[PATCH v5 3/3] media: stm32-dcmi: add support of several sub-devices

[Hugues Fruchet]

Add support of several sub-devices within pipeline instead
of a single one.
This allows to support a CSI-2 camera sensor connected
through a CSI-2 to parallel bridge.

Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Hugues Fruchet <hugues.fruchet@st.com>
---
 drivers/media/platform/stm32/stm32-dcmi.c | 195 +++++++++++++++++++++++++++---
 1 file changed, 177 insertions(+), 18 deletions(-)

diff --git a/drivers/media/platform/stm32/stm32-dcmi.c b/drivers/media/platform/stm32/stm32-dcmi.c
index 6f37617..7c21805 100644
--- a/drivers/media/platform/stm32/stm32-dcmi.c
+++ b/drivers/media/platform/stm32/stm32-dcmi.c
@@ -172,6 +172,7 @@ struct stm32_dcmi {
 
 	struct media_device		mdev;
 	struct media_pad		vid_cap_pad;
+	struct media_pipeline		pipeline;
 };
 
 static inline struct stm32_dcmi *notifier_to_dcmi(struct v4l2_async_notifier *n)
@@ -583,6 +584,131 @@ static void dcmi_buf_queue(struct vb2_buffer *vb)
 	spin_unlock_irq(&dcmi->irqlock);
 }
 
+static struct media_entity *dcmi_find_source(struct stm32_dcmi *dcmi)
+{
+	struct media_entity *entity = &dcmi->vdev->entity;
+	struct media_pad *pad;
+
+	/* Walk searching for entity having no sink */
+	while (1) {
+		pad = &entity->pads[0];
+		if (!(pad->flags & MEDIA_PAD_FL_SINK))
+			break;
+
+		pad = media_entity_remote_pad(pad);
+		if (!pad || !is_media_entity_v4l2_subdev(pad->entity))
+			break;
+
+		entity = pad->entity;
+	}
+
+	return entity;
+}
+
+static int dcmi_pipeline_s_fmt(struct stm32_dcmi *dcmi,
+			       struct v4l2_subdev_pad_config *pad_cfg,
+			       struct v4l2_subdev_format *format)
+{
+	struct media_entity *entity = &dcmi->entity.source->entity;
+	struct v4l2_subdev *subdev;
+	struct media_pad *sink_pad = NULL;
+	struct media_pad *src_pad = NULL;
+	struct media_pad *pad = NULL;
+	struct v4l2_subdev_format fmt = *format;
+	bool found = false;
+	int ret;
+
+	/*
+	 * Starting from sensor subdevice, walk within
+	 * pipeline and set format on each subdevice
+	 */
+	while (1) {
+		unsigned int i;
+
+		/* Search if current entity has a source pad */
+		for (i = 0; i < entity->num_pads; i++) {
+			pad = &entity->pads[i];
+			if (pad->flags & MEDIA_PAD_FL_SOURCE) {
+				src_pad = pad;
+				found = true;
+				break;
+			}
+		}
+		if (!found)
+			break;
+
+		subdev = media_entity_to_v4l2_subdev(entity);
+
+		/* Propagate format on sink pad if any, otherwise source pad */
+		if (sink_pad)
+			pad = sink_pad;
+
+		dev_dbg(dcmi->dev, "%s[%d] pad format set to 0x%x %ux%u\n",
+			subdev->name, pad->index, format->format.code,
+			format->format.width, format->format.height);
+
+		fmt.pad = pad->index;
+		ret = v4l2_subdev_call(subdev, pad, set_fmt, pad_cfg, &fmt);
+		if (ret < 0)
+			return ret;
+
+		/* Walk to next entity */
+		sink_pad = media_entity_remote_pad(src_pad);
+		if (!sink_pad || !is_media_entity_v4l2_subdev(sink_pad->entity))
+			break;
+
+		entity = sink_pad->entity;
+	}
+	*format = fmt;
+
+	return 0;
+}
+
+static int dcmi_pipeline_s_stream(struct stm32_dcmi *dcmi, int state)
+{
+	struct media_entity *entity = &dcmi->vdev->entity;
+	struct v4l2_subdev *subdev;
+	struct media_pad *pad;
+	int ret;
+
+	/* Start/stop all entities within pipeline */
+	while (1) {
+		pad = &entity->pads[0];
+		if (!(pad->flags & MEDIA_PAD_FL_SINK))
+			break;
+
+		pad = media_entity_remote_pad(pad);
+		if (!pad || !is_media_entity_v4l2_subdev(pad->entity))
+			break;
+
+		entity = pad->entity;
+		subdev = media_entity_to_v4l2_subdev(entity);
+
+		ret = v4l2_subdev_call(subdev, video, s_stream, state);
+		if (ret < 0 && ret != -ENOIOCTLCMD) {
+			dev_err(dcmi->dev, "%s: %s failed to %s streaming (%d)\n",
+				__func__, subdev->name,
+				state ? "start" : "stop", ret);
+			return ret;
+		}
+
+		dev_dbg(dcmi->dev, "%s is %s\n",
+			subdev->name, state ? "started" : "stopped");
+	}
+
+	return 0;
+}
+
+static int dcmi_pipeline_start(struct stm32_dcmi *dcmi)
+{
+	return dcmi_pipeline_s_stream(dcmi, 1);
+}
+
+static void dcmi_pipeline_stop(struct stm32_dcmi *dcmi)
+{
+	dcmi_pipeline_s_stream(dcmi, 0);
+}
+
 static int dcmi_start_streaming(struct vb2_queue *vq, unsigned int count)
 {
 	struct stm32_dcmi *dcmi = vb2_get_drv_priv(vq);
@@ -597,14 +723,17 @@ static int dcmi_start_streaming(struct vb2_queue *vq, unsigned int count)
 		goto err_release_buffers;
 	}
 
-	/* Enable stream on the sub device */
-	ret = v4l2_subdev_call(dcmi->entity.source, video, s_stream, 1);
-	if (ret && ret != -ENOIOCTLCMD) {
-		dev_err(dcmi->dev, "%s: Failed to start streaming, subdev streamon error",
-			__func__);
+	ret = media_pipeline_start(&dcmi->vdev->entity, &dcmi->pipeline);
+	if (ret < 0) {
+		dev_err(dcmi->dev, "%s: Failed to start streaming, media pipeline start error (%d)\n",
+			__func__, ret);
 		goto err_pm_put;
 	}
 
+	ret = dcmi_pipeline_start(dcmi);
+	if (ret)
+		goto err_media_pipeline_stop;
+
 	spin_lock_irq(&dcmi->irqlock);
 
 	/* Set bus width */
@@ -676,7 +805,7 @@ static int dcmi_start_streaming(struct vb2_queue *vq, unsigned int count)
 	if (ret) {
 		dev_err(dcmi->dev, "%s: Start streaming failed, cannot start capture\n",
 			__func__);
-		goto err_subdev_streamoff;
+		goto err_pipeline_stop;
 	}
 
 	/* Enable interruptions */
@@ -687,8 +816,11 @@ static int dcmi_start_streaming(struct vb2_queue *vq, unsigned int count)
 
 	return 0;
 
-err_subdev_streamoff:
-	v4l2_subdev_call(dcmi->entity.source, video, s_stream, 0);
+err_pipeline_stop:
+	dcmi_pipeline_stop(dcmi);
+
+err_media_pipeline_stop:
+	media_pipeline_stop(&dcmi->vdev->entity);
 
 err_pm_put:
 	pm_runtime_put(dcmi->dev);
@@ -713,13 +845,10 @@ static void dcmi_stop_streaming(struct vb2_queue *vq)
 {
 	struct stm32_dcmi *dcmi = vb2_get_drv_priv(vq);
 	struct dcmi_buf *buf, *node;
-	int ret;
 
-	/* Disable stream on the sub device */
-	ret = v4l2_subdev_call(dcmi->entity.source, video, s_stream, 0);
-	if (ret && ret != -ENOIOCTLCMD)
-		dev_err(dcmi->dev, "%s: Failed to stop streaming, subdev streamoff error (%d)\n",
-			__func__, ret);
+	dcmi_pipeline_stop(dcmi);
+
+	media_pipeline_stop(&dcmi->vdev->entity);
 
 	spin_lock_irq(&dcmi->irqlock);
 
@@ -937,8 +1066,7 @@ static int dcmi_set_fmt(struct stm32_dcmi *dcmi, struct v4l2_format *f)
 	mf->width = sd_framesize.width;
 	mf->height = sd_framesize.height;
 
-	ret = v4l2_subdev_call(dcmi->entity.source, pad,
-			       set_fmt, NULL, &format);
+	ret = dcmi_pipeline_s_fmt(dcmi, NULL, &format);
 	if (ret < 0)
 		return ret;
 
@@ -1529,7 +1657,20 @@ static int dcmi_graph_notify_complete(struct v4l2_async_notifier *notifier)
 	struct stm32_dcmi *dcmi = notifier_to_dcmi(notifier);
 	int ret;
 
+	/*
+	 * Now that the graph is complete,
+	 * we search for the source subdevice
+	 * in order to expose it through V4L2 interface
+	 */
+	dcmi->entity.source =
+		media_entity_to_v4l2_subdev(dcmi_find_source(dcmi));
+	if (!dcmi->entity.source) {
+		dev_err(dcmi->dev, "Source subdevice not found\n");
+		return -ENODEV;
+	}
+
 	dcmi->vdev->ctrl_handler = dcmi->entity.source->ctrl_handler;
+
 	ret = dcmi_formats_init(dcmi);
 	if (ret) {
 		dev_err(dcmi->dev, "No supported mediabus format found\n");
@@ -1574,12 +1715,30 @@ static int dcmi_graph_notify_bound(struct v4l2_async_notifier *notifier,
 				   struct v4l2_async_subdev *asd)
 {
 	struct stm32_dcmi *dcmi = notifier_to_dcmi(notifier);
+	unsigned int ret;
+	int src_pad;
 
 	dev_dbg(dcmi->dev, "Subdev %s bound\n", subdev->name);
 
-	dcmi->entity.source = subdev;
+	/*
+	 * Link this sub-device to DCMI, it could be
+	 * a parallel camera sensor or a bridge
+	 */
+	src_pad = media_entity_get_fwnode_pad(&subdev->entity,
+					      subdev->fwnode,
+					      MEDIA_PAD_FL_SOURCE);
+
+	ret = media_create_pad_link(&subdev->entity, src_pad,
+				    &dcmi->vdev->entity, 0,
+				    MEDIA_LNK_FL_IMMUTABLE |
+				    MEDIA_LNK_FL_ENABLED);
+	if (ret)
+		dev_err(dcmi->dev, "Failed to create media pad link with subdev %s\n",
+			subdev->name);
+	else
+		dev_dbg(dcmi->dev, "DCMI is now linked to %s\n", subdev->name);
 
-	return 0;
+	return ret;
 }
 
 static const struct v4l2_async_notifier_operations dcmi_graph_notify_ops = {
-- 
2.7.4