linux-kernel - Re: Question about fixed regulator DT properties

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Message-ID: <5476266E.9040901@mentor.com>
Date:	Wed, 26 Nov 2014 21:13:50 +0200
From:	Vladimir Zapolskiy <vladimir_zapolskiy@...tor.com>
To:	Mark Brown <broonie@...nel.org>
CC:	Liam Girdwood <lgirdwood@...il.com>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>
Subject: Re: Question about fixed regulator DT properties

Hi, MarkOn 26.11.2014 19:53, Mark Brown wrote:
> On Wed, Nov 26, 2014 at 07:27:06PM +0200, Vladimir Zapolskiy wrote:
>> On 25.11.2014 14:17, Mark Brown wrote:
> 
>> b) "regulator-boot-on" does not mean that the regulator is controlled by
>> bootloader or firmware exclusively.
> 
> That's correct...
> 
>>>>> Should documentation be updated to reflect "regulator-boot-on" role that
>>>>> a regulator is re-enabled by the kernel?
> 
>>> I'm confused about this.  That's the sole purpose of the flag and as far
>>> as I can tell it's what the documentation says.
> 
>> Documentation/devicetree/bindings/regulator/regulator.txt says:
> 
>>   - regulator-boot-on: bootloader/firmware enabled regulator
> 
>> I would suggest to add Linux kernel to that list of regulator
>> controllers, if it is the intention. In its current state the
>> documentation makes an impression that "regulator-boot-on" property
>> instructs the kernel to ignore regulator setup, since it is already
>> controlled by bootloader or firmware.
> 
> No, not at all.  It's referring to the state when Linux starts.
> 

thank you for clarification, to grasp the underlying policy let me ask
for some more information.

If I want to enable a fixed regulator (not controlled by
bootloader/firmware) by Linux on boot or when fixed.ko module is bound,
shall I specify the same "regulator-boot-on" property? At least this is
the practical way to enable a fixed and/or gpio regulator right now, but
is it correct?

Or should the regulator always be enabled externally (assuming
"regulator-always-on" is omitted) after registration independently on
"regulator-boot-on" property?

--
With best wishes,
Vladimir
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