Hi Guennadi, On Friday 30 Dec 2016 14:04:34 Guennadi Liakhovetski wrote: > On Fri, 30 Dec 2016, Laurent Pinchart wrote: > > On Friday 30 Dec 2016 11:43:02 Guennadi Liakhovetski wrote: > >> Hi Laurent, > >> > >> I'd like to discuss extending this patch a bit, preferably as an > >> incremental patch. > >> > >> First let me confirm my current understanding of the way the UVC driver > >> creates its media device topology. Do I understand it correctly, that > >> the driver allocates UVC entities (not media controller entities) for all > >> UVC units and terminals, but then uses subdevices for all such UVC > >> entities, except terminals, i.e. only for UVC units? struct uvc_entity > >> has an embedded struct v4l2_subdev object, but it's unused for UVC > >> terminals. Instead terminals are associated to video devices, which are > >> then linked into the MC topology? Is this my understanding correct? > > > > That's correct, but looking at the code now, I think the driver should use > > a struct media_entity directly instead of a struct v4l2_subdev as it > > doesn't need any of the infrastructure provided by subdevs. > > > >> I have a problem with the current version of this patch, that there is > >> no way to associate video device nodes with respepctive metadata nodes. > >> Would it be acceptable to use an MC link for this association? > > > > No, links describe data connections. > > Well, it is data - it's metadata, extracted from USB buffers. > > >> Is it allowed for video device MC entities to have source pads > >> additionally to their (usually single) sink pad(s) (in case of input > >> video devices)? If that would be acceptable, I could create an additional > >> patch to add a source pad to output terminal video nodes to link it to > >> metadata nodes. > > > > That's a hack, I don't think it's a good idea. > > Ok, would a completely specialised one-off sysfs solution be better? Maybe > a link under the metadata node to the main node? Come on, I know you're better than that. Stop thinking short term about the quickest hack that can provide the feature you need. -- Regards, Laurent Pinchart -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
