Dear Lars-Peter Clausen, > On 07/19/2012 04:23 PM, Marek Vasut wrote: > > Dear Lars-Peter Clausen, > > > > Sorry for my late reply, got busy with other crazy stuff. > > > > [...] > > > >>>> Is there any reason not to use the mxs_lradc struct directly has the > >>>> iio data? > >>> > >>> I explained it below in the patch. I hope we'll eventually support the > >>> delay triggers, which will need 4 separate IIO devices. And this is > >>> where this structure will be augmented by other components. > >> > >> Ok I saw the comment, but it wasn't obvious to me that delay channels > >> will require multiple IIO devices. Might make sense to state this > >> explicitly. > > > > Fixed. > > > >>>>> [...] > >>>>> > >>>>> + > >>>>> +/* > >>>>> + * Channel management > >>>>> + * > >>>>> + * This involves crazy mapping between 8 virtual channels the CTRL4 > >>>>> register + * can harbor and 16 channels total this hardware supports. > >>>>> + */ > >>>> > >>>> I suppose this means only a maximum 8 channels can be active at a > >>>> time. I've recently posted a patch which makes it easy to implement > >>>> such a restriction. > >>>> http://www.spinics.net/lists/linux-iio/msg05936.html and > >>>> http://www.spinics.net/lists/linux-iio/msg05935.html for an example > >>>> validate callback implementation. In your case you'd check for > >>>> bitmap_weight(...) <= 8. Those patches are not yet in IIO though. > >>> > >>> This is good. When do you expect this to hit linux-next possibly? Or at > >>> least linux-iio? > >> > >> soon, hopefully. > > > > So I checked this, not sure how it'll help me though. > > Right now with your driver you can enable any combination of channels. If > more than 8 channels are enabled and you start sampling it will fail, since > not all channels can be mapped. With those patch you can implement a > validate callback and check for bitmap_weight(scan_mask) <= 8. This will > ensure that it is not possible to select more than 8 channels at once, > which again means that starting sampling can't fail of this. Thanks, got it ! Best regards, Marek Vasut -- To unsubscribe from this list: send the line "unsubscribe linux-iio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
