On Wednesday 23 February 2011 17:02:57 Hans Verkuil wrote: > On Wednesday, February 23, 2011 16:30:42 Laurent Pinchart wrote: > > On Wednesday 23 February 2011 15:06:49 Aguirre, Sergio wrote: > > > <snip> > > > > > > > > The only static data I am concerned about are those that affect > > > > > signal integrity. > > > > > > > > > > After thinking carefully about this I realized that there is really > > > > > only one setting that is relevant to that: the sampling edge. The > > > > > polarities do not matter in this. > > > > > > I respectfully disagree. > > > > So do I. Sampling edge is related to polarities, so you need to take both > > into account. > > When you switch polarity for data/field/hsync/vsync signals on a simple bus > you just invert whether a 1 bit is output as high or low voltage. So you > just change the meaning of the bit. This does not matter for signal > integrity, since you obviously have to be able to sample both low and high > voltages. It is *when* you sample that can have a major effect. When you switch the polarity you will likely have to sample on the opposite edge. If, for signal integrity reasons, you can only sample on a given edge, you will want to use a fixed polarity and not negotiate it. Given the very small number of parameters that are negotiated by soc-camera at the moment, I'm very much in favour of hardcoding all of them in platform data and just adding a g_interface_parms subdev operation. > This might be different for differential clocks. I have no experience with > this, so I can't say anything sensible about that. -- 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
