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

From: "Phani A, Rama Krishna" <rphani@codeaurora.org>
To: Stanimir Varbanov <stanimir.varbanov@linaro.org>,
	Jonathan Cameron <jic23@kernel.org>,
	linux-iio@vger.kernel.org, devicetree@vger.kernel.org
Cc: robh@kernel.org, linux-arm-msm@vger.kernel.org,
	smohanad@codeaurora.org, mgautam@codeaurora.org,
	sivaa@codeaurora.org, knaack.h@gmx.de, lars@metafoo.de,
	pmeerw@pmeerw.net, Julia.Lawall@lip6.fr
Subject: Re: [PATCH V3 2/2] iio: adc: spmi-vadc: Changes to support different scaling
Date: Tue, 1 Nov 2016 11:02:40 +0530	[thread overview]
Message-ID: <7f924788-daf1-c75f-59e9-fa4a0bf42c36@codeaurora.org> (raw)
In-Reply-To: <7c0baa96-51a1-06fb-7a90-1bfb3338a294@linaro.org>

Hi Stan,

On 31-Oct-16 2:56 PM, Stanimir Varbanov wrote:
> Hi Rama,
>
> On 10/31/2016 09:12 AM, Rama Krishna Phani A wrote:
>> 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@codeaurora.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.
>
> The interrupts DT property in binding doc is marked as optional already,
> so I can't really understand what you are trying to achieve with this
> new qcom,vadc-poll-eoc boolean property?
>
Agree., interrupts property is sufficient for this functionality. Will 
remove this DT binding in next patch.

Thanks,
Ramakrishna