On 20/12/15 11:19, Ricardo Ribalda Delgado wrote: > Hello Jonthan > > Thanks for your comments, I have fixed all the style problems in v2, > so we can focus in the range parameter. > > On Sat, Dec 19, 2015 at 5:31 PM, Jonathan Cameron <jic23@xxxxxxxxxx> wrote: >> Range isn't actually specified in the ABI docs. >> Documenation\ABI\testing\sysfs-bus-iio* >> The control interface for this is normally scale rather than range >> (we had to pick one of the two and that is the way it fell out) Usually >> hardware designers care about range, but userspace programs are often >> most directly interested in scale factors that need to be applied. >> (and that was my most rediculously over generalized statement for the day ;) > > What about a first version of the driver where the range is set via > pdata and is not userland configurable? > That way the four chips will be supported and we can have more > feedback from other users about the range issue. That would be fine. Generally I'd imagine a given board will only want to have one sensible choice anyway! (other than devkits at least) > >> >> I can see this is rather complex here given the random looking collection >> of associated scales and offsets. You would have to have _available >> attributes to say what offsets are available at a given scale I think. >> Also we'd have to then define a precedence order in the docs for the >> two attributes (worth doing to make it obvious what to do when this >> sort of setup arises). > > The problem with that approach is that there will be two operations to > set the range: one to change the scale, and another for the offset. The output > voltage will change twice in this process and may have an intermediate value > that can damage a circuit. Fair point - I had not thought of that. Hmm.. Could add a commit type attribute but that's ugly too. Even if we do allow changing the range ultimately, I think it would need some hard restrictions in platform data on what is 'safe' for a particular board. > > I also believe that my approach with a text description is more user friendly > (but problably because I programmed it :P) > > In any case, I will implement whatever we agree ;) For now, pdata sounds like the best plan and revisit this at a later date. Jonathan > > Best regards! > -- > 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 > -- 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
