On 26/11/2021 02:59, Laurent Pinchart wrote: > 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. Argh! Sorry, will do >> 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(+) >>
