Hi Michael, On Tuesday 20 March 2012 11:06:56 Michael Jones wrote: > On 03/20/2012 12:22 AM, Laurent Pinchart wrote: > > On Friday 16 March 2012 15:06:15 Michael Jones wrote: > [snip] > > > Adding a R/W bit to the flag argument should indeed work. However, I'm > > wondering what your use case for reading parameters back is. > > The simplest use case in my mind is that after the user has fiddled around > with config parameters, they should be able to set them back to their > original state. For that, they need to know what the original state was. > > > The preview engine parameter structures seem pretty-much self-contained to > > me, I'm not sure it would make sense to only modify one of the parameters. > > Why doesn't it make sense to write to only e.g. 'COEF3' in the PRV_WBGAIN > register? Especially considering the sparse documentation of many of these > registers, I would like to be able to tweak the existing parameters from > their defaults, rather than start from scratch. Because configuring white balance requires modifying all the coefficients. I agree that querying the default parameters can be useful for experimentation purpose, although in that case you could just have a look at the driver source code ;-) I've sent a patch that modifies the way the preview engine handles the configuration process to the linux-media mailing list. I could try implementing read access on top of that, but I'm not sure when I'll have time to do so. If you want to give it a try, I'll review your code :-) Be careful of the race conditions, they're not trivial. -- 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
