Re: [PATCH V6 1/9] PM / OPP: Introduce "power-domain-opp" property

[Sudeep Holla <sudeep.holla@arm.com>]

On 28/04/17 21:48, Rob Herring wrote:
> On Wed, Apr 26, 2017 at 04:27:05PM +0530, Viresh Kumar wrote:
>> Power-domains need to express their active states in DT and the devices
>> within the power-domain need to express their dependency on those active
>> states. The power-domains can use the OPP tables without any
>> modifications to the bindings.
>>
>> Add a new property "power-domain-opp", which will contain phandle to the
>> OPP node of the parent power domain. This is required for devices which
>> have dependency on the configured active state of the power domain for
>> their working.
>>
>> For some platforms the actual frequency and voltages of the power
>> domains are managed by the firmware and are so hidden from the high
>> level operating system. The "opp-hz" property is relaxed a bit to
>> contain indexes instead of actual frequency values to support such
>> platforms.
>>
>> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
>> ---
>>  Documentation/devicetree/bindings/opp/opp.txt | 74 ++++++++++++++++++++++++++-
>>  1 file changed, 73 insertions(+), 1 deletion(-)
>>
>> diff --git a/Documentation/devicetree/bindings/opp/opp.txt b/Documentation/devicetree/bindings/opp/opp.txt
>> index 63725498bd20..6e30cae2a936 100644
>> --- a/Documentation/devicetree/bindings/opp/opp.txt
>> +++ b/Documentation/devicetree/bindings/opp/opp.txt
>> @@ -77,7 +77,10 @@ This defines voltage-current-frequency combinations along with other related
>>  properties.
>>  
>>  Required properties:
>> -- opp-hz: Frequency in Hz, expressed as a 64-bit big-endian integer.
>> +- opp-hz: Frequency in Hz, expressed as a 64-bit big-endian integer. In some
>> +  cases the exact frequency in Hz may be hidden from the OS by the firmware and
>> +  this field may contain values that represent the frequency in a firmware
>> +  dependent way, for example an index of an array in the firmware.
> 
> Not really sure OPP binding makes sense here. What about all the other 
> properties. We expose voltage, but not freq?
> 

I completely agree with that and I have been pushing this to be
represented as just regulators[0]. Mark B seem to dislike that
idea [1]

-- 
Regards,
Sudeep

[0] http://www.spinics.net/lists/devicetree/msg174725.html
[1] http://www.spinics.net/lists/devicetree/msg175113.html