[libcamera-devel] [PATCH v8 13/13] libcamera: ipu3: Enable ImgU media links

[Jacopo Mondi]

As the lengthy comment reports, link enable/disable is not trivial, as
links in one ImgU instance interfere with capture operations in the
other one. As it is not yet clear if this behaviour is intended, as of
now reset the media graph during pipeline's match() and enable the
required links at streamConfiguration time.

Reviewed-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
Reviewed-by: Niklas Söderlund <niklas.soderlund at ragnatech.se>
Signed-off-by: Jacopo Mondi <jacopo at jmondi.org>
---
 src/libcamera/pipeline/ipu3/ipu3.cpp | 102 +++++++++++++++++++++++++++
 1 file changed, 102 insertions(+)

diff --git a/src/libcamera/pipeline/ipu3/ipu3.cpp b/src/libcamera/pipeline/ipu3/ipu3.cpp
index a1e53c9a5a06..48205301f1ae 100644
--- a/src/libcamera/pipeline/ipu3/ipu3.cpp
+++ b/src/libcamera/pipeline/ipu3/ipu3.cpp
@@ -73,6 +73,11 @@ public:
 	int start();
 	int stop();
 
+	int linkSetup(const std::string &source, unsigned int sourcePad,
+		      const std::string &sink, unsigned int sinkPad,
+		      bool enable);
+	int enableLinks(bool enable);
+
 	unsigned int index_;
 	std::string name_;
 	MediaDevice *media_;
@@ -263,6 +268,14 @@ int PipelineHandlerIPU3::configureStreams(Camera *camera,
 		return -EINVAL;
 	}
 
+	/*
+	 * \todo: Enable links selectively based on the requested streams.
+	 * As of now, enable all links unconditionally.
+	 */
+	ret = data->imgu_->enableLinks(true);
+	if (ret)
+		return ret;
+
 	/*
 	 * Pass the requested stream size to the CIO2 unit and get back the
 	 * adjusted format to be propagated to the ImgU output devices.
@@ -474,6 +487,30 @@ bool PipelineHandlerIPU3::match(DeviceEnumerator *enumerator)
 		return false;
 	}
 
+	/*
+	 * FIXME: enabled links in one ImgU instance interfere with capture
+	 * operations on the other one. This can be easily triggered by
+	 * capturing from one camera and then trying to capture from the other
+	 * one right after, without disabling media links in the media graph
+	 * first.
+	 *
+	 * The tricky part here is where to disable links on the ImgU instance
+	 * which is currently not in use:
+	 * 1) Link enable/disable cannot be done at start/stop time as video
+	 * devices needs to be linked first before format can be configured on
+	 * them.
+	 * 2) As link enable has to be done at the least in configureStreams,
+	 * before configuring formats, the only place where to disable links
+	 * would be 'stop()', but the Camera class state machine allows
+	 * start()<->stop() sequences without any streamConfiguration() in
+	 * between.
+	 *
+	 * As of now, disable all links in the media graph at 'match()' time,
+	 * to allow testing different cameras in different test applications
+	 * runs. A test application that would use two distinct cameras without
+	 * going through a library teardown->match() sequence would fail
+	 * at the moment.
+	 */
 	if (imguMediaDev_->disableLinks())
 		goto error;
 
@@ -885,6 +922,71 @@ int ImgUDevice::stop()
 	return ret;
 }
 
+/**
+ * \brief Enable or disable a single link on the ImgU instance
+ *
+ * This method assumes the media device associated with the ImgU instance
+ * is open.
+ *
+ * \return 0 on success or a negative error code otherwise
+ */
+int ImgUDevice::linkSetup(const std::string &source, unsigned int sourcePad,
+			  const std::string &sink, unsigned int sinkPad,
+			  bool enable)
+{
+	MediaLink *link = media_->link(source, sourcePad, sink, sinkPad);
+	if (!link) {
+		LOG(IPU3, Error)
+			<< "Failed to get link: '" << source << "':"
+			<< sourcePad << " -> '" << sink << "':" << sinkPad;
+		return -ENODEV;
+	}
+
+	return link->setEnabled(enable);
+}
+
+/**
+ * \brief Enable or disable all media links in the ImgU instance to prepare
+ * for capture operations
+ *
+ * \todo This method will probably be removed or changed once links will be
+ * enabled or disabled selectively.
+ *
+ * \return 0 on success or a negative error code otherwise
+ */
+int ImgUDevice::enableLinks(bool enable)
+{
+	std::string viewfinderName = name_ + " viewfinder";
+	std::string outputName = name_ + " output";
+	std::string statName = name_ + " 3a stat";
+	std::string inputName = name_ + " input";
+	int ret;
+
+	/* \todo Establish rules to handle media devices open/close. */
+	ret = media_->open();
+	if (ret)
+		return ret;
+
+	ret = linkSetup(inputName, 0, name_, PAD_INPUT, enable);
+	if (ret)
+		goto done;
+
+	ret = linkSetup(name_, PAD_OUTPUT, outputName, 0, enable);
+	if (ret)
+		goto done;
+
+	ret = linkSetup(name_, PAD_VF, viewfinderName, 0, enable);
+	if (ret)
+		goto done;
+
+	ret = linkSetup(name_, PAD_STAT, statName, 0, enable);
+
+done:
+	media_->close();
+
+	return ret;
+}
+
 /*------------------------------------------------------------------------------
  * CIO2 Device
  */
-- 
2.21.0