Re: [PATCH 0/2] blue part 6: IIO abi rework

[Jonathan Cameron <jic23@cam.ac.uk>]

On 07/28/11 09:08, Hennerich, Michael wrote:
> Jonathan Cameron wrote on 2011-07-28:
>> On 07/27/11 15:41, Michael Hennerich wrote:
>>> On 07/26/2011 01:06 PM, Jonathan Cameron wrote:
>>>> On 07/26/11 11:52, Michael Hennerich wrote:
>>>>> On 07/26/2011 11:17 AM, Jonathan Cameron wrote:
>>>>>> On 07/26/11 10:01, Hennerich, Michael wrote:
>>>>>>> Jonathan Cameron wrote on 2011-07-25:
>>>>>>>> Michael pointed out the issues that not having an explicit
>>>>>>>> direction for channels was causing and the inconsistency of the
>>>>>>>> inX and outX channel naming we got from hmwon.
>>>>>>>>
>>>>>>>> They are stuck with it, but we aren't, so lets fix this now.
>>>>>>>>
>>>>>>>> Interesting question is whether we reset the base units to be
>>>>>>>> volts whilst we are at it? (for voltage channels obviously!)
>>>>>>> What do you mean exactly volts versus milli volts?
>>>>>> Make the in_voltage_scale correspond to conversion to volts instead
>>>>>> of millivolts as now (I think). Err. Looking at it that isn't
>>>>>> actually documented... oops.  I wonder which drivers actually do
>>>>>> that and which don't.
>>>>> The ones I wrote provide the scale for millivolts.
>>>>> With the recent introduction of IIO_VAL_INT_PLUS_NANO we got the
>>>>> scale accurate enough for the precession 24-bit converters.
>>>>> If we move to the SI base unit volt, we lose this accuracy again.
>>>> Yup, that's the principal counter argument to the change.
>>> If we decide to leave the milli scale for volts... Do we also want to
>>> stay with milli degrees Celsius, etc.? If we do it for one, probably
>>> best to do it for them all..
> 
> Hi Jonathan,
> 
> So stick with the milli scale for all?
Yes.
> 
>>>
>>> One other thing we should also address is the
>>> byte-ordering/endianess of the scan elements stored in the ring buffers.
>>>
>>> Right now the scan_element type details signs, bits, storage bits and
>>> shifts. However it lacks to tell the endianess within the storage bits.
>>> Good point. I'd completely forgotten about that.
>>>
>>> How about le:s16/32>>0 or be:s16/32>>0 for example?
>> Yup, that works for me.  In cases where it doesn't matter they driver
>> can pick one at random.
> 
> 
> We need another case - Some drivers use the (be|le)(x)_to_cpu() helpers,
> So in case these are used the endianess can be either or, depending on the host.
> So maybe have le|be|cpu?
I thought about that, but am inclined to say we just stop drivers doing the conversion.
Better to leave it up to userspace?
> 
> 
> Greetings,
> Michael
> 
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