On Wed, May 22, 2013 at 3:39 PM, Lars-Peter Clausen <lars@xxxxxxxxxx> wrote: > On 05/22/2013 03:29 PM, Guillaume Ballet wrote: >> On Wed, May 22, 2013 at 1:43 PM, Lars-Peter Clausen <lars@xxxxxxxxxx> wrote: >>> On 05/22/2013 11:37 AM, Guillaume Ballet wrote: >>>>>> >>>>>>> >>>>>>>> functions' signature only has one integer >>>>>>>> in/out parameter. That makes sense in the context of _raw because the >>>>>>>> value isn't yet processed. >>>>>>>> >>>>>>>> However, as the scale is a number encoded over two ints, the >>>>>>>> _processed value should also span two ints. Is there a reason why it's >>>>>>>> still only one int? >>>>>>> >>>>>>> No it certainly should not be one int for exactly the reasons you have >>>>>>> stated. >>>>>>>> >>>>>>>> >>>>>> >>>>>> I'm not to sure about that. I'd rather add a scale parameter to the >>>>>> iio_read_channel_processed, just in the same way the >>>>>> convert_raw_to_processed function takes a scale parameter. >>>>> >>>>> That may be tricky to do given we often have nasty non linear functions >>>>> that are the reason we are using processed in the first place. Hmm. >>>>> Not sure which way works better. >>>> >>>> I agree, this is the whole point of using processed. Lars, is there a >>>> specific reason why you want to keep reading the value and the scale >>>> in different function calls? >>> >>> I don't want to keep reading scale and value in different function calls. >>> >>> What's you use case and how do you want to split the data between the two >>> integers? >> >> Since the scale's format can be IIO_VAL_INT_PLUS_MICRO and >> IIO_VAL_INT_PLUS_NANO, etc... and since iio_read_channel_processed >> returns a value that is homogeneous to (value * scale), it seems to me >> the same format should be used as when calling iio_read_channel_raw >> with IIO_CHAN_INFO_SCALE. My use case is not more complicated than >> making sure I keep the same precision when getting processed values. > > That doesn't really help me understand what you are trying to do. What is > your application, where do you call iio_read_channel_processed and how do > you process the returned value. I have a driver for an ADC block that measures miscellaneous values in various units (temperature, voltage, current...) to be read from drivers in other kernel subsystems (the power supply class, for instance). Unit conversion has to be done by the IIO device itself as it's done using tables that are provided by various vendors who don't want them published. Hence my need to call iio_read_channel_processed and not entrust anyone else with the conversion. Could _you_ please explain what your concern with using the same format is? Guillaume -- 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
