Re: [PATCH v4 0/2] iio: adc: Add Maxim MAX11100 driver

[Jonathan Cameron <jic23-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>]

On 15/01/17 14:13, jacopo mondi wrote:
> Hi Jonathan,
>    thanks for review,
> 
> On 13/01/2017 10:50, Jacopo Mondi wrote:
>> Hello,
>>    sending out v4 splitting device tree bindings documentation and actual ADC
>> driver.
>> No changes in driver code since v3.
>>
>> Same question for iio maintainers here:
>> I would like to have clarified the measure unit returned by read_raw().
>> Currently (value_raw * value_scale) return the ADC input value in mV.
Good.
>> While testing the patch I've been questioned if that should not actually
>> be in uV. This is easily achievable making _scale return a value in uV.
>> I have found no mention of this in the ABI documentation as it speaks of
>> generic voltage. Can we have a final word on this?
> 
> I see you have reviewed the driver without complaining for the
> read_raw() measure unit, so I assume this replies to the above
> question as well...
> 
The units are specified in Documentation/ABI/testing/sysfs-bus-iio.

> What:		/sys/bus/iio/devices/iio:deviceX/in_voltageY_raw
> What:		/sys/bus/iio/devices/iio:deviceX/in_voltageY_supply_raw
> What:		/sys/bus/iio/devices/iio:deviceX/in_voltageY_i_raw
> What:		/sys/bus/iio/devices/iio:deviceX/in_voltageY_q_raw
> KernelVersion:	2.6.35
> Contact:	linux-iio-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
> Description:
> 		Raw (unscaled no bias removal etc.) voltage measurement from
> 		channel Y. In special cases where the channel does not
> 		correspond to externally available input one of the named
> 		versions may be used. The number must always be specified and
> 		unique to allow association with event codes. Units after
> 		application of scale and offset are millivolts.

So millivolts.  This comes from a, perhaps ill judged, decision to match
hwmon units were we could.

Jonathan

> Thanks j
> 
>>
>> Thanks Marek for having tested this.
>>
>> v1 -> v2:
>>     - incorporated pmeerw's review comments
>>     - retrieve vref from dts and use that to convert read_raw result
>>       to mV
>>     - add device tree bindings documentation
>>
>> v2 -> v3:
>>     - add _SCALE bit of read_raw function and change _RAW bit accordingly
>>     - call regulator_get_voltage when accessing the _SCALE part of read_raw
>>       and not during probe
>>     - add back remove function as regulator has to be disabled when detaching
>>       the module. Do not use devm_ version of iio_register/unregister functions
>>       anymore but do unregister in the remove.
>>     - remove mutex as access to SPI bus is protected by SPI core. Thanks marex
>>
>> v3 -> v4:
>>     - split device tree binding documentation and actual ADC driver
>>     - add "reg" to the list of required properties and use a better
>>       namimg for the adc device node in bindings documentation as suggested
>>       by Geert.
>>
>> Jacopo Mondi (2):
>>   iio: adc: Add Maxim MAX11100 driver
>>   dt-bindings: iio: document MAX11100 ADC
>>
>>  .../devicetree/bindings/iio/adc/max11100.txt       |  19 +++
>>  drivers/iio/adc/Kconfig                            |   9 +
>>  drivers/iio/adc/Makefile                           |   1 +
>>  drivers/iio/adc/max11100.c                         | 187 +++++++++++++++++++++
>>  4 files changed, 216 insertions(+)
>>  create mode 100644 Documentation/devicetree/bindings/iio/adc/max11100.txt
>>  create mode 100644 drivers/iio/adc/max11100.c
>>
> 

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