Re: [PATCH V3 2/2] iio: adc: spmi-vadc: Changes to support different scaling

[Rama Krishna Phani A <rphani-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org>]

Hi Jonathan,

On 30-Oct-16 10:43 PM, Jonathan Cameron wrote:
> On 27/10/16 18:37, Phani A, Rama Krishna wrote:
>> Hi Stan,
>>
>> On 27-Oct-16 4:48 PM, Stanimir Varbanov wrote:
>>> Hi Rama,
>>>
>>> On 10/26/2016 05:41 PM, Rama Krishna Phani A wrote:
>>>> Polling can also be used for End of conversion completion. Implement logic
>>>> to choose either polling or interrupt for End of conversion completion.
>>>> Scaling can be done on the voltage to report adc code in physical units.
>>>> Add changes to support different scale functions to convert adc code to
>>>> physical units.
>>>>
>>>> Signed-off-by: Rama Krishna Phani A <rphani-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org>
>>>> ---
>>>>  .../devicetree/bindings/iio/adc/qcom,spmi-vadc.txt |  14 ++
>>>>  drivers/iio/adc/qcom-spmi-vadc.c                   | 263 +++++++++++++++++----
>>>>  2 files changed, 236 insertions(+), 41 deletions(-)
>>>>
>>>> diff --git a/Documentation/devicetree/bindings/iio/adc/qcom,spmi-vadc.txt b/Documentation/devicetree/bindings/iio/adc/qcom,spmi-vadc.txt
>>>> index 0fb4613..39e31c0e 100644
>>>> --- a/Documentation/devicetree/bindings/iio/adc/qcom,spmi-vadc.txt
>>>> +++ b/Documentation/devicetree/bindings/iio/adc/qcom,spmi-vadc.txt
>>>> @@ -37,6 +37,12 @@ VADC node:
>>>>      Value type: <prop-encoded-array>
>>>>      Definition: End of conversion interrupt.
>>>>
>>>> +- qcom,vadc-poll-eoc:
>>>> +    Usage: optional
>>>> +    Value type: <bool>
>>>> +    Definition: Use polling instead of interrupts for End of Conversion
>>>> +        completion.
>>>
>>> Why you need to add such a flag in DT?
>>>
>>> The DT should describe hardware details not how the driver will choose
>>> pooling vs interrupt.
>>>
>>> On which use-case you would prefer pooling?
>>>
>>
>> Few PMIC's support interrupt functionality for ADC where as few
>> PMIC's dont support. Based on the functionality that is supported in
>> hardware we choose whether to go for polling or for interrupt.
> Can't use the usual trick of an optional interrupt in DT?
> If it's there we try to use it, if not then fall back to polling?
>
Ok., Will check this logic for implementation and will post next patch.

>
>>>> +
>>>>  Channel node properties:
>>>>
>>>>  - reg:
>>>> @@ -92,6 +98,14 @@ Channel node properties:
>>>>              Valid values are: 1, 2, 4, 8, 16, 32, 64, 128, 256, 512
>>>>              If property is not found, 1 sample will be used.
>>>>
>>>> +- qcom,scale-function:
>>>> +    Usage: optional
>>>> +    Value type: <u32>
>>>> +    Definition: Scaling function used to convert raw ADC code to
>>>> +    units specific to a given channel. Scaled units can be
>>>> +    microvolts, millidegC.Valid values are: 0, 1, 2, 3, 4.
>>>> +    If property is not found, 0 scaling will be used.
>>>
>>> This shouldn't be in DT binding. Just select the scale function for each
>>> channel in the driver based on compatible property.
>>>
>>>
>> Ok ., Will remove this binding from DT, implement logic in driver and will post next patch.
>>
>> Thanks,
>> Ramakrishna
>>
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