Hi Sakari,
>>> In omap3isp/isp.c: isp_fwnodes_parse() the async notifier is registered looking
>>> at the endpoints parent fwnode:
>>>
>>> isd->asd.match.fwnode.fwnode =
>>> fwnode_graph_get_remote_port_parent(fwnode);
>>>
>>> This would therefore not support ADV748x ... (it wouldn't know which TX/CSI
>>> entity to match against)
>>>
>>> So the way I see it is that all devices which currently register an async
>>> notifier should now register the match against the endpoint instead of the
>>> parent device:
>>>
>>> - isd->asd.match.fwnode.fwnode = fwnode_graph_get_remote_port_parent(fwnode);
>>> + isd->asd.match.fwnode.fwnode = fwnode;
>>>
>>> And then if we adapt the match to check against:
>>> fwnode == fwnode || fwnode == fwnode_graph_get_remote_port_parent(fwnode);
>>
>> That's not enough as a master driver may use device node whereas the
>> sub-device driver uses endpoint node. You need to do it both ways.
>>
I've worked through this and I'm convinced that it should not be both ways...
We are matching a Subdevice (SD) to an Async Subdevice Notifier (ASD)
Bringing in 'endpoints' gives us the following match combinations
SD ASD : Result
ep ep : Match ... Subdevices can specify their endpoint node.
Notifiers can be updated to also specify the (remote) endpoint.
dev ep : Match - We should take the parent of the ASD to match SD,
to support subdevices which default to their device node.
dev dev : Match - This is the current case for all other drivers
but Notifier ASDs can be converted to EP's
ep dev : No Match - We should *not* take the parent of the SD
If a subdevice has specified it's endpoint, (ADV748x)
Matching against the parent device is invalid.
Finding and matching the parent of the SD would allow a driver to register a
notifier ASD with a dev node, and expect to match a subdevice that has
registered it's subdev with an EP node. This would erroneously allow drivers to
register a notifier that would match against *both* of the ADV748x CSI2 entities.
I have posted an implementation of this as:
[PATCH v1 3/3] v4l: async: Match parent devices [0]
I believe this to be correct - but I'm aware that I'm only really considering
the OF side here... Please let me know if there's something I'm not taking into
account.
[0] https://www.spinics.net/lists/linux-media/msg115677.html
Regards
--
Kieran
