Hi Philipp, On Wed, Oct 12, 2016 at 03:26:48PM +0200, Philipp Zabel wrote: > On Fri, Oct 7, 2016 at 11:52 PM, Sakari Ailus <sakari.ailus@xxxxxx> wrote: > > Hi Philipp, > > > > On Fri, Oct 07, 2016 at 06:00:47PM +0200, Philipp Zabel wrote: > >> Currently the v4l2_async_notifier needs to be given a list of matches > >> for all expected subdevices on creation. When chaining subdevices that > >> are asynchronously probed via device tree, the bridge device that sets > >> up the notifier does not know the complete list of subdevices, as it > >> can only parse its own device tree node to obtain information about > >> the nearest neighbor subdevices. > >> To support indirectly connected subdevices, we need to support amending > >> the existing notifier waiting list with newly found neighbor subdevices > >> with each registered subdevice. > > > > Could you elaborate a little what's the exact use case for this? What kind > > of a device? > > On i.MX6 there's a > > DW MIPI CSI2 host -> Mux -> IPU/CSI > > path and all three are asynchronous subdevices in my patchset and only > the last one is directly known to the media device from the device > tree, since each driver should only parse its own device tree node an > can not follow the of_graph over multiple steps. Ok. Are all these devices part of the SoC? Is the mux doing something else than just sitting in between the two? :-) > Another use case I have seen in the wild are external GPIO controlled > multiplexers or LVDS serializer/deserializer pairs between a parallel > camera and parallel capture interface. In each case the bridge node > can only determine its closest neighbor from the device tree (the mux, > the LVDS deserializer) but does not know about the indirectly > connected device nodes further upstream. Yeah, true. -- Kind regards, Sakari Ailus e-mail: sakari.ailus@xxxxxx XMPP: sailus@xxxxxxxxxxxxxx -- 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
