On Fri, Nov 26, 2021 at 12:16:01AM +0000, Daniel Scally wrote: > Hello all > > This series is not yet ready to merge, but I wanted to share it as I know some > other folks are working in similar areas at the moment (and I am including the > libcamera devel list for the same reason) Seems you forgot to CC libcamera-devel :-) Let's fix that on v2. > At present there's no means in the kernel of describing the supporting > relationship between subdevices that work together to form an effective single > unit - the type example in this case being a camera sensor and its > corresponding vcm. To attempt to solve that, this series adds a new type of > media link called MEDIA_LNK_FL_ANCILLARY_LINK, which connects two instances of > struct media_entity. Further work would be needed to document it properly, and > there may be ramifications within the v4l2-core which I have not yet discovered > (a lot of places seem to assume that media_entity->links means pad-2-pad links, > so some extra work might be needed to validate the link type before doing any > thing to them). > > The mechanism of connection I have modelled as a notifier and async subdev, > which seemed the best route since sensor drivers already typically will call > v4l2_async_register_subdev_sensor() on probe, and that function already looks > for a reference to a firmware node with the reference named "lens-focus". To > avoid boilerplate in the sensor drivers, I added some new functions in > v4l2-async that are called in v4l2_async_match_notify() to create the ancillary > links - checking the entity.function of both notifier and subdev to make sure > that's appropriate. I haven't gone further than that yet, but I suspect we could > cut down on code elsewhere by, for example, also creating pad-to-pad links in > the same place. > > Thoughts and comments very welcome :) > > Dan > > Daniel Scally (2): > media: entity: Add support for ancillary links > media: v4l2-async: Create links during v4l2_async_match_notify() > > drivers/media/mc/mc-entity.c | 30 ++++++++++++++++ > drivers/media/v4l2-core/v4l2-async.c | 51 ++++++++++++++++++++++++++++ > include/media/media-entity.h | 30 ++++++++++++++++ > include/uapi/linux/media.h | 1 + > 4 files changed, 112 insertions(+) > -- Regards, Laurent Pinchart
