Date:   Tue, 11 Jun 2019 10:48:32 +0200
From:   Hugues Fruchet <hugues.fruchet@...com>
To:     Alexandre Torgue <alexandre.torgue@...com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Hans Verkuil <hverkuil@...all.nl>,
        Sakari Ailus <sakari.ailus@...ux.intel.com>
CC:     <linux-media@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>,
        <linux-stm32@...md-mailman.stormreply.com>,
        Benjamin Gaignard <benjamin.gaignard@...aro.org>,
        Yannick Fertre <yannick.fertre@...com>,
        Philippe CORNU <philippe.cornu@...com>,
        "Hugues Fruchet" <hugues.fruchet@...com>,
        Mickael GUENE <mickael.guene@...com>
Subject: [PATCH v2 3/3] media: stm32-dcmi: add support of several sub-devices

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.

Signed-off-by: Hugues Fruchet <hugues.fruchet@...com>
---
 drivers/media/platform/stm32/stm32-dcmi.c | 207 +++++++++++++++++++++++++++---
 1 file changed, 189 insertions(+), 18 deletions(-)

diff --git a/drivers/media/platform/stm32/stm32-dcmi.c b/drivers/media/platform/stm32/stm32-dcmi.c
index 3a69783..144912f 100644
--- a/drivers/media/platform/stm32/stm32-dcmi.c
+++ b/drivers/media/platform/stm32/stm32-dcmi.c
@@ -173,6 +173,7 @@ 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)
@@ -584,6 +585,135 @@ static void dcmi_buf_queue(struct vb2_buffer *vb)
 	spin_unlock_irq(&dcmi->irqlock);
 }
 
+static struct media_entity *dcmi_find_sensor(struct stm32_dcmi *dcmi)
+{
+	struct media_entity *entity = &dcmi->vdev->entity;
+	struct v4l2_subdev *subdev;
+	struct media_pad *pad;
+
+	/* Walk searching for entity having no sink */
+	while (1) {
+		pad = &entity->pads[0];
+
+		subdev = media_entity_to_v4l2_subdev(entity);
+
+		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->sensor->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);
@@ -598,14 +728,17 @@ 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->sensor, 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 */
@@ -677,7 +810,7 @@ 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 */
@@ -688,8 +821,11 @@ static int dcmi_start_streaming(struct vb2_queue *vq, unsigned int count)
 
 	return 0;
 
-err_subdev_streamoff:
-	v4l2_subdev_call(dcmi->sensor, 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);
@@ -714,13 +850,10 @@ 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->sensor, 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);
 
@@ -938,8 +1071,7 @@ 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->sensor, pad,
-			       set_fmt, NULL, &format);
+	ret = dcmi_pipeline_s_fmt(dcmi, NULL, &format);
 	if (ret < 0)
 		return ret;
 
@@ -1530,7 +1662,19 @@ 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 camera sensor subdevice
+	 * in order to expose it through V4L2 interface
+	 */
+	dcmi->sensor = media_entity_to_v4l2_subdev(dcmi_find_sensor(dcmi));
+	if (!dcmi->sensor) {
+		dev_err(dcmi->dev, "No camera sensor subdevice found\n");
+		return -ENODEV;
+	}
+
 	dcmi->vdev->ctrl_handler = dcmi->sensor->ctrl_handler;
+
 	ret = dcmi_formats_init(dcmi);
 	if (ret) {
 		dev_err(dcmi->dev, "No supported mediabus format found\n");
@@ -1574,12 +1718,30 @@ 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->sensor = 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 = {
@@ -1639,6 +1801,15 @@ static int dcmi_graph_init(struct stm32_dcmi *dcmi)
 		return ret;
 	}
 
+	/* Register all the subdev nodes */
+	ret = v4l2_device_register_subdev_nodes(&dcmi->v4l2_dev);
+	if (ret) {
+		dev_err(dcmi->dev, "Failed to register subdev nodes\n");
+		v4l2_async_notifier_unregister(&dcmi->notifier);
+		of_node_put(dcmi->entity.node);
+		return ret;
+	}
+
 	return 0;
 }
 
-- 
2.7.4

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