[libcamera-devel] [PATCH v4 2/2] pipeline: raspberrypi: Add support for Video Mux and Bridge devices

[Jacopo Mondi]

Hi Naush

On Tue, Dec 14, 2021 at 02:00:02PM +0000, Naushir Patuck wrote:
> This change will allow the pipeline handler to enumerate and control Video
> Mux or Bridge devices that may be attached between sensors and a particular
> Unicam instance. Cascaded mux or bridge devices are also handled.
>
> A new member function RPiCameraData::enumerateVideoDevices(), called from
> PipelineHandlerRPi::registerCamera(), is used to identify and open all mux and
> bridge subdevices present in the sensor -> Unicam link.
>
> Relevent links are enabled/disabled and pad formats correctly set in
> PipelineHandlerRPi::configure() before the camera is started.
>
> Signed-off-by: Naushir Patuck <naush at raspberrypi.com>
> Reviewed-by: Kieran Bingham <kieran.bingham at ideasonboard.com>
> ---
>  .../pipeline/raspberrypi/raspberrypi.cpp      | 139 ++++++++++++++++++
>  1 file changed, 139 insertions(+)
>
> diff --git a/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp b/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
> index 2a2fb5273eb8..4ec646d3c7a3 100644
> --- a/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
> +++ b/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
> @@ -12,6 +12,7 @@
>  #include <mutex>
>  #include <queue>
>  #include <unordered_set>
> +#include <utility>
>
>  #include <libcamera/base/shared_fd.h>
>  #include <libcamera/base/utils.h>
> @@ -191,6 +192,8 @@ public:
>  	int loadIPA(ipa::RPi::SensorConfig *sensorConfig);
>  	int configureIPA(const CameraConfiguration *config);
>
> +	void enumerateVideoDevices(MediaLink *link);
> +
>  	void statsMetadataComplete(uint32_t bufferId, const ControlList &controls);
>  	void runIsp(uint32_t bufferId);
>  	void embeddedComplete(uint32_t bufferId);
> @@ -220,6 +223,11 @@ public:
>  	std::vector<RPi::Stream *> streams_;
>  	/* Stores the ids of the buffers mapped in the IPA. */
>  	std::unordered_set<unsigned int> ipaBuffers_;
> +	/*
> +	 * Stores a cascade of Video Mux or Bridge devices between the sensor and
> +	 * Unicam together with media link across the entities.
> +	 */
> +	std::vector<std::pair<std::unique_ptr<V4L2Subdevice>, MediaLink *>> bridgeDevices_;
>
>  	/* DMAHEAP allocation helper. */
>  	RPi::DmaHeap dmaHeap_;
> @@ -868,6 +876,38 @@ int PipelineHandlerRPi::configure(Camera *camera, CameraConfiguration *config)
>  	 */
>  	data->properties_.set(properties::ScalerCropMaximum, data->sensorInfo_.analogCrop);
>
> +	/* Setup the Video Mux/Bridge entities. */
> +	for (auto &[device, link] : data->bridgeDevices_) {
> +		/*
> +		 * Start by disabling all the sink pad links on the devices in the
> +		 * cascade, with the exception of the link connecting the device.
> +		 */
> +		for (const MediaPad *p : device->entity()->pads()) {
> +			if (!(p->flags() & MEDIA_PAD_FL_SINK))
> +				continue;
> +
> +			for (MediaLink *l : p->links()) {
> +				if (l != link)
> +					l->setEnabled(false);
> +			}
> +		}
> +
> +		/* Next, enable the entity -> entity links, and setup the pad format. */
> +		link->setEnabled(true);
> +		const MediaPad *srcPad = link->sink();

sinkPad ?

> +		ret = device->setFormat(srcPad->index(), &sensorFormat);
> +		if (ret) {
> +			LOG(RPI, Error) << "Failed to set format on " << device->entity()->name()
> +					<< " pad " << srcPad->index()
> +					<< " with format  " << format.toString()
> +					<< ": " << ret;
> +			return ret;
> +		}
> +
> +		LOG(RPI, Info) << "Configured media link on device " << device->entity()->name()
> +			       << " on pad " << srcPad->index();
> +	}
> +
>  	return ret;
>  }
>
> @@ -1098,6 +1138,13 @@ int PipelineHandlerRPi::registerCamera(MediaDevice *unicam, MediaDevice *isp, Me
>  	if (data->sensor_->init())
>  		return -EINVAL;
>
> +	/*
> +	 * Enumerate all the Video Mux/Bridge devices across the sensor -> unicam
> +	 * link. There may be a cascade of devices in this link!
> +	 */
> +	MediaLink *link = sensorEntity->getPadByIndex(0)->links()[0];
> +	data->enumerateVideoDevices(link);
> +
>  	data->sensorFormats_ = populateSensorFormats(data->sensor_);
>
>  	ipa::RPi::SensorConfig sensorConfig;
> @@ -1447,6 +1494,98 @@ int RPiCameraData::configureIPA(const CameraConfiguration *config)
>  	return 0;
>  }
>
> +/*
> + * enumerateVideoDevices() iterates over the Media Controller topology, starting
> + * at the sensor and finishing at Unicam. For each sensor, RPiCameraData stores
> + * a unique list of any intermediate video mux or bridge devices connected in a
> + * cascade, together with the entity to entity link.
> + *
> + * Entity pad configuration and link enabling happens at the end of configure().
> + * We first disables all pad links on each entity device in the chain, and then
> + * selectively enabling the specific links to link sensor to Unicam across all
> + * intermediate muxes and bridges.
> + *
> + * In the cascaded topology below, if Sensor1 is used, the Mux2 -> Mux1 link
> + * will be disabled, and Sensor1 -> Mux1 -> Unicam links enabled. Alternatively,
> + * if Sensor3 is used, the Sensor2 -> Mux2 and Sensor1 -> Mux1 links are disabled,
> + * and Sensor3 -> Mux2 -> Mux1 -> Unicam links are enabled. All other links will
> + * remain unchanged.
> + *
> + *  +----------+
> + *  |  Unicam  |
> + *  +-----^----+
> + *        |
> + *    +---+---+
> + *    |  Mux1 <-------+
> + *    +--^----+       |
> + *       |            |
> + * +-----+---+    +---+---+
> + * | Sensor1 |    |  Mux2 |<--+
> + * +---------+    +-^-----+   |
> + *                  |         |
> + *          +-------+-+   +---+-----+
> + *          | Sensor2 |   | Sensor3 |
> + *          +---------+   +---------+
> + */
> +void RPiCameraData::enumerateVideoDevices(MediaLink *link)
> +{
> +	const MediaPad *sinkPad = link->sink();
> +	const MediaEntity *entity = sinkPad->entity();
> +	bool unicamFound = false;
> +
> +	/* We only deal with Video Mux and Bridge devices in cascade. */
> +	if (entity->function() != MEDIA_ENT_F_VID_MUX &&
> +	    entity->function() != MEDIA_ENT_F_VID_IF_BRIDGE)
> +		return;
> +
> +	/* Find the source pad for this Video Mux or Bridge device. */
> +	const MediaPad *entitySourcePad = nullptr;
> +	for (const MediaPad *pad : entity->pads()) {
> +		if (pad->flags() & MEDIA_PAD_FL_SOURCE) {
> +			/*
> +			 * We can only deal with devices that have a single source
> +			 * pad. If this device has multple source pads, ignore it
> +			 * and this branch in the cascade.
> +			 */
> +			if (entitySourcePad)
> +				return;

Probably failing loud and saying that a bridge/mux with multiple
source pads cannot be handled is more explicit ?
Ah you will fail later though at the end of recursion...


> +
> +			entitySourcePad = pad;

Can this just be sourcePad ? Or were you trying to express that this
lives in the 'next' entity and it's not the link's source pad ?

> +		}
> +	}
> +
> +	LOG(RPI, Info) << "Found video mux device " << entity->name()
> +		       << " linked to sink pad " << sinkPad->index();
> +
> +	bridgeDevices_.emplace_back(std::make_unique<V4L2Subdevice>(entity), link);
> +	bridgeDevices_.back().first->open();
> +
> +	/*
> +	 * Iterate through all the sink pad links down the cascade to find any
> +	 * other Video Mux and Bridge devices.
> +	 */
> +	for (MediaLink *l : entitySourcePad->links()) {
> +		enumerateVideoDevices(l);
> +		/* Once we reach the Unicam entity, we are done. */
> +		if (l->sink()->entity()->name() == "unicam-image") {
> +			unicamFound = true;
> +			break;
> +		}
> +	}
> +
> +	/* This identifies the end of our entity enumeration recursion. */
> +	if (link->source()->entity()->function() == MEDIA_ENT_F_CAM_SENSOR) {
> +		/*
> +		* If Unicam is not at the end of this cascade, we cannot configure
> +		* this topology automatically, so remove all entity references.
> +		*/
> +		if (!unicamFound) {
> +			LOG(RPI, Warning) << "Cannot automatically configure this MC topology!";
> +			bridgeDevices_.clear();
> +		}
> +	}
> +}
> +
>  void RPiCameraData::statsMetadataComplete(uint32_t bufferId, const ControlList &controls)
>  {
>  	if (state_ == State::Stopped)
> --
> 2.25.1
>