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Subject[PATCH v2 1/3] media: v4l2-common: add helper functions to call s_stream() callbacks
Date
Add v4l2_pipeline_stream_{enable,disable} helper functions to iterate
through the subdevices in a given stream (i.e following links from sink
to source) and call .s_stream() callback.

Add stream_count on the subdevice object for simultaneous streaming from
different video devices which shares subdevices.

Prevent calling .s_stream(true) if it was already called previously by
another stream.

Prevent calling .s_stream(false) from one stream when there are still
others active.

If .s_stream(true) fails, call .s_stream(false) in the reverse order.

Signed-off-by: Helen Koike <helen.koike@collabora.com>

---

Changes in v2:
- re-write helpers to not use media walkers

drivers/media/v4l2-core/v4l2-common.c | 117 ++++++++++++++++++++++++++
include/media/v4l2-common.h | 28 ++++++
include/media/v4l2-subdev.h | 2 +
3 files changed, 147 insertions(+)

diff --git a/drivers/media/v4l2-core/v4l2-common.c b/drivers/media/v4l2-core/v4l2-common.c
index d0e5ebc736f9f..379d4bf4f8128 100644
--- a/drivers/media/v4l2-core/v4l2-common.c
+++ b/drivers/media/v4l2-core/v4l2-common.c
@@ -441,3 +441,120 @@ int v4l2_fill_pixfmt(struct v4l2_pix_format *pixfmt, u32 pixelformat,
return 0;
}
EXPORT_SYMBOL_GPL(v4l2_fill_pixfmt);
+
+/*
+ * v4l2_pipeline_subdevs_get - Assemble a list of subdevices in a pipeline
+ * @subdevs: the array to be filled
+ * @size: the array size
+ *
+ * Walk from a video node, following link from sink to source and fill the
+ * array with subdevices in the path.
+ *
+ * Note: this function follows the first enabled link in a sink pad found in a
+ * given entity. Thus it won't work if there are entities with multiple enabled
+ * links to its sink pads in the topology.
+ *
+ * Return the number of subdevices filled in the array.
+ */
+static unsigned int v4l2_pipeline_subdevs_get(struct video_device *vdev,
+ struct v4l2_subdev **subdevs,
+ unsigned int size)
+{
+ struct media_entity *entity = &vdev->entity;
+ unsigned int idx = 0;
+
+ while (1) {
+ struct media_pad *src_pad = NULL;
+ unsigned int i;
+
+ /* Find remote source pad */
+ for (i = 0; i < entity->num_pads; i++) {
+ struct media_pad *sink_pad = &entity->pads[i];
+
+ if (!(sink_pad->flags & MEDIA_PAD_FL_SINK))
+ continue;
+
+ src_pad = media_entity_remote_pad(sink_pad);
+ if (src_pad &&
+ is_media_entity_v4l2_subdev(src_pad->entity))
+ break;
+ }
+ if (i == entity->num_pads)
+ break;
+
+ if (idx >= size) {
+ WARN_ON(1);
+ return 0;
+ }
+
+ entity = src_pad->entity;
+ subdevs[idx++] = media_entity_to_v4l2_subdev(entity);
+ }
+
+ return idx;
+}
+
+__must_check int v4l2_pipeline_stream_enable(struct video_device *vdev)
+{
+ struct media_device *mdev = vdev->entity.graph_obj.mdev;
+ struct v4l2_subdev *subdevs[MEDIA_ENTITY_ENUM_MAX_DEPTH];
+ struct v4l2_subdev *sd;
+ unsigned int i, size;
+ int ret;
+
+ mutex_lock(&mdev->graph_mutex);
+
+ size = v4l2_pipeline_subdevs_get(vdev, subdevs, ARRAY_SIZE(subdevs));
+
+ for (i = 0; i < size; i++) {
+ sd = subdevs[i];
+ if (sd->stream_count++)
+ continue;
+ dev_dbg(mdev->dev,
+ "enabling stream for '%s'\n", sd->entity.name);
+ ret = v4l2_subdev_call(sd, video, s_stream, true);
+ if (ret && ret != -ENOIOCTLCMD)
+ goto err_stream_disable;
+ }
+
+ mutex_unlock(&mdev->graph_mutex);
+ return 0;
+
+err_stream_disable:
+ do {
+ sd = subdevs[i];
+ if (--sd->stream_count)
+ continue;
+ dev_dbg(mdev->dev,
+ "disabling stream for '%s'\n", sd->entity.name);
+ v4l2_subdev_call(sd, video, s_stream, false);
+ } while (i--);
+
+ mutex_unlock(&mdev->graph_mutex);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(v4l2_pipeline_stream_enable);
+
+void v4l2_pipeline_stream_disable(struct video_device *vdev)
+{
+ struct media_device *mdev = vdev->entity.graph_obj.mdev;
+ struct v4l2_subdev *subdevs[MEDIA_ENTITY_ENUM_MAX_DEPTH];
+ unsigned int size;
+
+ mutex_lock(&mdev->graph_mutex);
+
+ size = v4l2_pipeline_subdevs_get(vdev, subdevs, ARRAY_SIZE(subdevs));
+
+ while (size--) {
+ struct v4l2_subdev *sd = subdevs[size];
+
+ if (--sd->stream_count)
+ continue;
+ dev_dbg(mdev->dev,
+ "disabling stream for '%s'\n", sd->entity.name);
+ v4l2_subdev_call(sd, video, s_stream, false);
+ }
+
+ mutex_unlock(&mdev->graph_mutex);
+}
+EXPORT_SYMBOL_GPL(v4l2_pipeline_stream_disable);
diff --git a/include/media/v4l2-common.h b/include/media/v4l2-common.h
index 150ee16ebd811..e833610b0f66d 100644
--- a/include/media/v4l2-common.h
+++ b/include/media/v4l2-common.h
@@ -519,6 +519,34 @@ int v4l2_fill_pixfmt(struct v4l2_pix_format *pixfmt, u32 pixelformat,
int v4l2_fill_pixfmt_mp(struct v4l2_pix_format_mplane *pixfmt, u32 pixelformat,
u32 width, u32 height);

+/**
+ * v4l2_pipeline_stream_enable - Call .s_stream(true) callbacks in the stream
+ * @vdev: Starting video device
+ *
+ * Call .s_stream(true) callback in all the subdevices participating in the
+ * stream, i.e. following links from sink to source.
+ *
+ * Calls to this function can be nested, in which case the same number of
+ * v4l2_pipeline_stream_disable() calls will be required to stop streaming.
+ * The pipeline pointer must be identical for all nested calls to
+ * v4l2_pipeline_stream_enable().
+ */
+__must_check int v4l2_pipeline_stream_enable(struct video_device *vdev);
+
+/**
+ * v4l2_pipeline_stream_disable - Call .s_stream(false) callbacks in the stream
+ * @vdev: Starting video device
+ *
+ * Call .s_stream(true) callback in all the subdevices participating in the
+ * stream, i.e. following links from sink to source.
+ *
+ * Calls to this function can be nested, in which case the same number of
+ * v4l2_pipeline_stream_disable() calls will be required to stop streaming.
+ * The pipeline pointer must be identical for all nested calls to
+ * v4l2_pipeline_stream_enable().
+ */
+void v4l2_pipeline_stream_disable(struct video_device *vdev);
+
static inline u64 v4l2_buffer_get_timestamp(const struct v4l2_buffer *buf)
{
/*
diff --git a/include/media/v4l2-subdev.h b/include/media/v4l2-subdev.h
index a4848de598521..20f913a9f70c5 100644
--- a/include/media/v4l2-subdev.h
+++ b/include/media/v4l2-subdev.h
@@ -838,6 +838,7 @@ struct v4l2_subdev_platform_data {
* @subdev_notifier: A sub-device notifier implicitly registered for the sub-
* device using v4l2_device_register_sensor_subdev().
* @pdata: common part of subdevice platform data
+ * @stream_count: Stream count for the subdevice.
*
* Each instance of a subdev driver should create this struct, either
* stand-alone or embedded in a larger struct.
@@ -869,6 +870,7 @@ struct v4l2_subdev {
struct v4l2_async_notifier *notifier;
struct v4l2_async_notifier *subdev_notifier;
struct v4l2_subdev_platform_data *pdata;
+ unsigned int stream_count;
};


--
2.26.0
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