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[Note: the code is mostly from Laurent but the patch description is from Tomi] The media_pipeline_start() and media_pipeline_stop() functions use the media graph walk API to traverse the graph and validate the pipeline. The graph walk traverses the media graph following links between the entities. Also, while the pipeline can't change between the start and stop calls, the graph is walked again from scratch at stop time, or any time a driver needs to inspect the pipeline. With the upcoming multiplexed streams support we will need a bit more intelligent pipeline construction, as e.g. two independent streams may be passing through a single entity via separate pads in which case those pads should not be part of the same pipeline. This patch essentially rewrites the media_pipeline_start/stop so that a pipeline is defined as a set of pads instead of entities and the media graph traversal considers the pad interdependencies when choosing which links to follow. Currently all the entity's pads are considered as interdependent. This means that the behavior with all the current drivers stays the same, but in the future we can define a more fine-grained pipeline construction. Additionally the media pipeline's pads are cached at media_pipeline_start() time, and re-used at media_pipeline_stop() which avoid the need to re-walk the whole graph as the previous implementation did. Also, caching pads in the pipeline can serve in the future as the foundation to provide a better API than the media graph walk to drivers to iterate over pads and entities in the pipeline. Note that the old media_pipeline_start/stop used the media graph walk API. The new version does not use the media graph walk API, but instead a new implementation. There are two reasons for not changing the graph walk: it proved to be rather difficult to change the graph walk to have the features implemented in this patch, and second, this keeps the backward compatibility of the graph walk as there are users of the graph walk API The long term plan is that all the existing code would be converted to use the new cached pipeline, thus allowing us to remove the graph walk. Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com> Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org> |
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| .. | ||
| drivers | ||
| camera-sensor.rst | ||
| cec-core.rst | ||
| dtv-ca.rst | ||
| dtv-common.rst | ||
| dtv-core.rst | ||
| dtv-demux.rst | ||
| dtv-frontend.rst | ||
| dtv-net.rst | ||
| index.rst | ||
| maintainer-entry-profile.rst | ||
| mc-core.rst | ||
| rc-core.rst | ||
| tx-rx.rst | ||
| v4l2-async.rst | ||
| v4l2-common.rst | ||
| v4l2-controls.rst | ||
| v4l2-core.rst | ||
| v4l2-dev.rst | ||
| v4l2-device.rst | ||
| v4l2-dv-timings.rst | ||
| v4l2-event.rst | ||
| v4l2-fh.rst | ||
| v4l2-flash-led-class.rst | ||
| v4l2-fwnode.rst | ||
| v4l2-intro.rst | ||
| v4l2-mc.rst | ||
| v4l2-mediabus.rst | ||
| v4l2-mem2mem.rst | ||
| v4l2-rect.rst | ||
| v4l2-subdev.rst | ||
| v4l2-tuner.rst | ||
| v4l2-tveeprom.rst | ||
| v4l2-videobuf2.rst | ||
| v4l2-videobuf.rst | ||