Hi Guennadi, On Monday 19 December 2011 11:13:58 Guennadi Liakhovetski wrote: > On Mon, 19 Dec 2011, Laurent Pinchart wrote: > > On Monday 19 December 2011 09:09:34 Guennadi Liakhovetski wrote: > > > On Mon, 19 Dec 2011, Laurent Pinchart wrote: > > > > On Friday 16 December 2011 10:50:21 Guennadi Liakhovetski wrote: > > > > > On Fri, 16 Dec 2011, Scott Jiang wrote: > > > > > > >> How about this implementation? I know it's not for soc, but I > > > > > > >> post it to give my idea. > > > > > > >> Bridge knows the layout, so it doesn't need to query the > > > > > > >> subdevice. > > > > > > > > > > > > > > Where from? AFAIU, we are talking here about subdevice inputs, > > > > > > > right? In this case about various inputs of the TV decoder. How > > > > > > > shall the bridge driver know about that? > > > > > > > > > > > > I have asked this question before. Laurent reply me: > > > > > > > >> ENUMINPUT as defined by V4L2 enumerates input connectors > > > > > > > >> available on the board. Which inputs the board designer > > > > > > > >> hooked up is something that only the top-level V4L driver > > > > > > > >> will know. Subdevices do not have that information, so > > > > > > > >> enuminputs is not applicable there. > > > > > > > >> > > > > > > > >> Of course, subdevices do have input pins and output pins, > > > > > > > >> but these are assumed to be fixed. With the s_routing ops > > > > > > > >> the top level driver selects which input and output pins > > > > > > > >> are active. Enumeration of those inputs and outputs > > > > > > > >> wouldn't gain you anything as far as I can tell since the > > > > > > > >> subdevice simply does not know which inputs/outputs are > > > > > > > >> actually hooked up. It's the top level driver that has that > > > > > > > >> information (usually passed in through board/card info > > > > > > > >> structures). > > > > > > > > > > Laurent, right, I now remember reading this discussion before. But > > > > > I'm not sure I completely agree:-) Yes, you're right - the board > > > > > decides which pins are routed to which connectors. And it has to > > > > > provide this information to the driver in its platform data. But - > > > > > I think, this information should be provided not to the bridge > > > > > driver, but to respective subdevice drivers, because only they > > > > > know what exactly those interfaces are good for and how to report > > > > > them to the bridge or the user, if we decide to also export this > > > > > information over the subdevice user-space API. > > > > > > > > > > So, I would say, the board has to tell the subdevice driver: yes, > > > > > your inputs 0 and 1 are routed to external connectors. On input 1 > > > > > I've put a pullup, it is connected to connector of type X over a > > > > > circuit Y, clocked from your output Z, if the driver needs to know > > > > > all that. And the subdev driver will just tell the bridge only > > > > > what that one needs to know - number of inputs and their > > > > > capabilities. > > > > > > > > That sounds reasonable. > > > > > > Good, this would mean, we need additional subdevice operations along > > > the lines of enum_input and enum_output, and maybe also g_input and > > > g_output? > > > > What about implementing pad support in the subdevice ? Input enumeration > > could then be performed without a subdev operation. > > soc-camera doesn't support pad operations yet. soc-camera doesn't support enum_input yet either, so you need to implement something anyway ;-) You wouldn't need to call a pad operation here, you would just need to iterate through the pads provided by the subdev. -- 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
