Hi Hans, On Monday 26 July 2010 21:42:49 Hans Verkuil wrote: > On Monday 26 July 2010 18:12:55 Laurent Pinchart wrote: > > On Friday 23 July 2010 17:56:02 Karicheri, Muralidharan wrote: > > > Laurent, > > > > > > Could you explain the probe and active usage using an example such as > > > below? > > > > > > Link1 Link2 > > > > > > input sensor -> ccdc -> video node. > > > > > > Assume Link2 we can have either format 1 or format 2 for capture. > > > > Sure. > > > > The probe and active formats are used to probe supported formats and > > getting/setting active formats. > > Just to verify: we are dealing with mediabus formats here, right? That's correct. > One thing that I don't like is the name 'probe'. I would prefer the name > 'proposed'. You propose an input format and based on that you can enumerate > a list of proposed output format. I think that name fits better than > 'probe' which I find confusing in this context. I'm open to all kind of suggestions. Those patches were not posted for review, they're not final yet. They're just sample code. > > * Enumerating supported formats on the CCDC input and output would be > > done with the following calls > > > > ENUM_FMT(CCDC input pad) > > > > for the input, and > > > > S_FMT(PROBE, CCDC input pad, format) > > ENUM_FMT(CCDC output pad) > > > > for the output. > > How does ENUM_FMT know if it has to use the proposed or actual input > formats? Or is it supposed to always act on proposed formats? Enumeration always uses the probe/proposed formats. > > Setting the probe format on the input pad is required, as the format on > > an output pad usually depends on the format on input pads. > > > > * Trying a format on the CCDC input and output would be done with > > > > S_FMT(PROBE, CCDC input pad, format) > > > > for the input, and > > > > S_FMT(PROBE, CCDC input pad, format) > > S_FMT(PROBE, CCDC output pad, format) > > > > on the output. The S_FMT call will mangle the format given format if it > > can't be supported exactly, so there's no need to call G_FMT after S_FMT > > (a G_FMT call following a S_FMT call will return the same format as the > > S_FMT call). > > > > * Setting the active format is done with > > > > S_FMT(ACTIVE, CCDC input pad, format) > > S_FMT(ACTIVE, CCDC output pad, format) > > > > The formats will be applied to the hardware (possibly with a delay, > > drivers can delay register writes until STREAMON for instance). > > > > Probe formats are stored in the subdev file handles, so two applications > > trying formats at the same time will not interfere with each other. > > Active formats are stored in the device structure, so modifications done > > by an application are visible to other applications. > > > > Hope this helps clarifying the API. > > You know that I have never been happy with this approach, but I also have > to admit that I haven't found a better way of doing it. Once again I'm open to proposals/discussions/whatever (well, mostly whatever :-)). Let's concentrate on the media controller patches first, I'll then submit the next set and we'll discuss it. -- 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
