linux-kernel - Re: [PATCH V4 2/9] PM / Domains: Use OPP tables for power-domains

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Date:   Thu, 13 Apr 2017 14:45:16 +0100
From:   Sudeep Holla <sudeep.holla@....com>
To:     Viresh Kumar <viresh.kumar@...aro.org>
Cc:     Sudeep Holla <sudeep.holla@....com>,
        Rafael Wysocki <rjw@...ysocki.net>, ulf.hansson@...aro.org,
        Kevin Hilman <khilman@...aro.org>,
        linaro-kernel@...ts.linaro.org, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Stephen Boyd <sboyd@...eaurora.org>,
        Nishanth Menon <nm@...com>, robh+dt@...nel.org,
        lina.iyer@...aro.org, rnayak@...eaurora.org,
        devicetree@...r.kernel.org
Subject: Re: [PATCH V4 2/9] PM / Domains: Use OPP tables for power-domains



On 13/04/17 07:03, Viresh Kumar wrote:
> On 12-04-17, 17:58, Sudeep Holla wrote:
>>
>>
>> On 20/03/17 09:32, Viresh Kumar wrote:
>>> The OPP table bindings contains all the necessary fields to support
>>> power-domains now. Update the power-domain bindings to allow
>>> "operating-points-v2" to be present within the power-domain node.
>>>
>>> Also allow consumer devices, that don't use OPP tables, to specify the
>>> parent power-domain's performance level using the
>>> "domain-performance-state" property.
>>>
>>> Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>
>>> ---
>>>  .../devicetree/bindings/power/power_domain.txt     | 42 ++++++++++++++++++++++
>>>  1 file changed, 42 insertions(+)
>>>
>>> diff --git a/Documentation/devicetree/bindings/power/power_domain.txt b/Documentation/devicetree/bindings/power/power_domain.txt
>>> index 723e1ad937da..5db112fa5d7c 100644
>>> --- a/Documentation/devicetree/bindings/power/power_domain.txt
>>> +++ b/Documentation/devicetree/bindings/power/power_domain.txt
>>> @@ -38,6 +38,9 @@ phandle arguments (so called PM domain specifiers) of length specified by the
>>>    domain's idle states. In the absence of this property, the domain would be
>>>    considered as capable of being powered-on or powered-off.
>>>  
>>> +- operating-points-v2 : This describes the performance states of a PM domain.
>>> +  Refer to ../opp/opp.txt for more information.
>>> +
>>>  Example:
>>>  
>>>  	power: power-controller@...40000 {
>>> @@ -118,4 +121,43 @@ The node above defines a typical PM domain consumer device, which is located
>>>  inside a PM domain with index 0 of a power controller represented by a node
>>>  with the label "power".
>>>  
>>> +Optional properties:
>>> +- domain-performance-state: A positive integer value representing the minimum
>>> +  power-domain performance level required by the consumer device. The integer
>>> +  value '0' represents the lowest performance level and the higher values
>>> +  represent higher performance levels. The value of "domain-performance-state"
>>> +  field should match the "domain-performance-state" field of one of the OPP
>>> +  nodes in the parent power-domain's OPP table.
>>> +
>>> +
>>> +
>>> +Example:
>>> +
>>> +	domain_opp_table: opp_table {
>>> +		compatible = "operating-points-v2";
>>> +
>>> +		opp@1 {
>>> +			domain-performance-state = <1>;
>>> +			opp-microvolt = <975000 970000 985000>;
>>> +		};
>>> +		opp@2 {
>>> +			domain-performance-state = <2>;
>>> +			opp-microvolt = <1075000 1000000 1085000>;
>>> +		};
>>> +	};
>>> +
>>> +	parent: power-controller@...40000 {
>>> +		compatible = "foo,power-controller";
>>> +		reg = <0x12340000 0x1000>;
>>> +		#power-domain-cells = <0>;
>>> +		operating-points-v2 = <&domain_opp_table>;
>>
>> As mentioned in the other email, it would be good to consider
>> scalability with multiple power domains in a PM domain provider.
>> i.e case of #power-domain-cells = <1> or more
> 
> Yeah, but that isn't supported for devices today. So no point
> considering that today.
> 

Do you mean we don't support power controllers with multiple power
domains ? If yes, we do support #power-domain-cells=<1 or more> clearly
from the binding and this change simple doesn't scale with such power
controllers/power-domain providers.

-- 
Regards,
Sudeep