linux-kernel - Re: [RFC PATCH v2 1/3] regulator: bindings: Add properties for coupled regulators

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Date:   Wed, 25 Oct 2017 09:31:45 +0200
From:   Maciej Purski <m.purski@...sung.com>
To:     Rob Herring <robh@...nel.org>
Cc:     linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
        Mark Brown <broonie@...nel.org>,
        Liam Girdwood <lgirdwood@...il.com>,
        Mark Rutland <mark.rutland@....com>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
Subject: Re: [RFC PATCH v2 1/3] regulator: bindings: Add properties for
 coupled regulators



On 10/24/2017 08:58 PM, Rob Herring wrote:
> On Wed, Oct 18, 2017 at 02:47:00PM +0200, Maciej Purski wrote:
>> Some regulators require keeping their voltage spread below defined
>> max_spread.
>>
>> Add properties to provide information on regulators' coupling.
>>
>> Signed-off-by: Maciej Purski <m.purski@...sung.com>
>> ---
>>   Documentation/devicetree/bindings/regulator/regulator.txt | 4 ++++
>>   1 file changed, 4 insertions(+)
>>
>> diff --git a/Documentation/devicetree/bindings/regulator/regulator.txt b/Documentation/devicetree/bindings/regulator/regulator.txt
>> index 378f6dc..6769565 100644
>> --- a/Documentation/devicetree/bindings/regulator/regulator.txt
>> +++ b/Documentation/devicetree/bindings/regulator/regulator.txt
>> @@ -60,6 +60,10 @@ Optional properties:
>>   	0: Disable active discharge.
>>   	1: Enable active discharge.
>>   	Absence of this property will leave configuration to default.
>> +- regulator-coupled-with: Phandle to regulators with which the regulator
>> +  should be coupled. Allow up to 9 phandles.
> 
> 9? Sounds like a driver detail and pretty arbitrary.
> 
It's just a constant number that I defined as MAX_COUPLED, because in fact there 
isn't any use-case yet for even more than two regulators so MAX_COUPLED equal to 
9 is a really high number. If you find it cleaner, I can make this value variable.

> Is this linkage 2-way meaning 2 coupled regulators both have links to
> the other one? If so, then what happens when you have a high number? If
> not, how does one decide which regulator has this property?

Yes, it is 2-way. When you have a high number, then each regulator should have 
phandles to every other. So, if you have 3 regulators coupled, then each one 
should have 2 phandles.

> 
>> +- regulator-coupled-max-spread: Max spread between voltages of coupled regulators
>> +  in microvolts.
>>   
>>   Deprecated properties:
>>   - regulator-compatible: If a regulator chip contains multiple
>> -- 
>> 2.7.4
>>
> 
> 
>