linux-kernel - Re: [PATCH] regulator: dts: Fix bindings description of regulator-boot-on

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Message-ID: <5257D714.9060005@ti.com>
Date:	Fri, 11 Oct 2013 05:46:44 -0500
From:	Nishanth Menon <nm@...com>
To:	Rajendra Nayak <rnayak@...com>
CC:	Rob Landley <rob@...dley.net>, Mark Brown <broonie@...aro.org>,
	Rob Herring <rob.herring@...xeda.com>,
	Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	Stephen Warren <swarren@...dotorg.org>,
	Kishon Vijay Abraham I <kishon@...com>,
	<devicetree@...r.kernel.org>, <linux-doc@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] regulator: dts: Fix bindings description of regulator-boot-on

On 10/11/2013 05:33 AM, Rajendra Nayak wrote:
> On Friday 11 October 2013 03:56 PM, Nishanth Menon wrote:
>> Since regulator-boot-on property maps back to constraints->boot_on,
>> current description of 'regulator-boot-on' property conflicts with
>> description of 'boot-on' in include/linux/regulator/machine.h and the
>> corresponding implementation in drivers/regulator/core.c.
>>
>> Ensure the description is more inline with the original intent.
>>
>> Cc: Rajendra Nayak <rnayak@...com>
>>
>> Reported-by: Kishon Vijay Abraham I <kishon@...com>
>> Signed-off-by: Nishanth Menon <nm@...com>
>> ---
>>
>> Ref: my confusion in http://marc.info/?t=138140228800004&r=1&w=2
>> Based on v3.12-rc4 tag
>>
>>  .../devicetree/bindings/regulator/regulator.txt    |    4 +++-
>>  1 file changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/Documentation/devicetree/bindings/regulator/regulator.txt b/Documentation/devicetree/bindings/regulator/regulator.txt
>> index 2bd8f09..d999f096 100644
>> --- a/Documentation/devicetree/bindings/regulator/regulator.txt
>> +++ b/Documentation/devicetree/bindings/regulator/regulator.txt
>> @@ -8,7 +8,9 @@ Optional properties:
>>  - regulator-min-microamp: smallest current consumers may set
>>  - regulator-max-microamp: largest current consumers may set
>>  - regulator-always-on: boolean, regulator should never be disabled
>> -- regulator-boot-on: bootloader/firmware enabled regulator
>> +- regulator-boot-on: regulator is enabled when the system is initially started.
>> +  If the regulator is not enabled by the hardware or bootloader then it will be
>> +  enabled when the constraints are applied.
> 
> Isn't this specific to how the linux regulator framework implements it?
> why should it be documented in the generic bindings documentation which has
> nothing Linux specific but more hardware details?

Lets say for the moment that SMPS10 was enabled by hardware
/bootloader/firmware at boot.

By the description of "bootloader/firmware enabled regulator" , I have
described the dts correctly by adding regulator-boot-on. However,
translating that to implementation of "Keep the regulator enabled at
boot even if we dont use it in USB" makes no logical leap for me.

In fact, what does "bootloader/firmware enabled regulator" even mean
to OS? why should it even care if "bootloader/firmware enabled
regulator"? It cares about regulators that are mandatory to be kept on
at boot.

So, IMHO, either our implementation in regulator core is wrong, or we
are describing the wrong hardware property. This patch assumes the later.

-- 
Regards,
Nishanth Menon
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