On Mon, Aug 15, 2011 at 9:19 AM, Jonathan Cameron <jic23@xxxxxxxxx> wrote: > On 08/15/11 16:57, Paul Thomas wrote: >> On Mon, Aug 15, 2011 at 2:52 AM, Jonathan Cameron <jic23@xxxxxxxxx> wrote: >>> On 08/14/11 21:18, Paul Thomas wrote: >>>> This uses the iio sysfs interface, and inculdes gain >>> includes >>> >>> Couple of left over bits from chan_spec conversion that need >>> cleaning up and a that gain attribute wants to be done via the >>> scale_shared chan_info element instead. >> OK, most of that makes sense. I might have more questions latter, but >> one question for now. You say to use the scale_shared for the gain >> (can you point do a good example of this?) I just want to make sure >> we're on the same page as to what the gain is doing. It's really just >> setting the range of the voltage input I scale the result back down to >> volts. So if the input voltage is 0.2V you get 0.2V Whether you set >> the gain to 1 or 8 > Ah, I missed that. In that case, given it's internal only, it should > be IIO_CHAN_INFO_CALIBSCALE_SHARED and you should be setting processed_val > in iio_chan_spec structures and scaling to millivolts not volts > (we may change everything to volts but haven't done it yet). > > For a device like this we tend to leave things raw and use the scale attribute > to tell userspace enough to know how to convert it to SI units. Doesn't > matter so much with devices only being accessed over sysfs (hence fine here) > but you don't want to waste time with conversions when pushing to a buffer. > > Jonathan > OK, but isn't this just about what the best way to report the values? What should the knob/hook from userspace be to set the gain/range? thanks, Paul -- 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
