Hi Guennadi, 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. -- 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
