linux-kernel - Re: [PATCH 1/2] regulator: DT: Add support to scale ramp delay based on platform behavior

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Message-ID: <56E943E9.5020503@nvidia.com>
Date:	Wed, 16 Mar 2016 17:00:49 +0530
From:	Laxman Dewangan <ldewangan@...dia.com>
To:	Mark Brown <broonie@...nel.org>
CC:	Bjorn Andersson <bjorn.andersson@...aro.org>, <robh+dt@...nel.org>,
	<pawel.moll@....com>, <mark.rutland@....com>,
	<ijc+devicetree@...lion.org.uk>, <lgirdwood@...il.com>,
	<bjorn.andersson@...ymobile.com>, <swarren@...dotorg.org>,
	<devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	Gandhar Dighe <gdighe@...dia.com>,
	Stuart Yates <syates@...dia.com>
Subject: Re: [PATCH 1/2] regulator: DT: Add support to scale ramp delay based
 on platform behavior


On Tuesday 15 March 2016 08:18 PM, Mark Brown wrote:
> * PGP Signed by an unknown key
>
> On Tue, Mar 15, 2016 at 07:11:23PM +0530, Laxman Dewangan wrote:
>
>> So here we will need two parameters:
>> advertised-ramp-delay for PMIC configurations and
>> ramp-delay which is measured one.
>> Most of time, advertised-ramp-delay is same as ramp-delay and hence one
>> value from DT will be sufficient.
>> If there is difference then both value can be provided and
>> advertised-ramp-delay  will be used for PMIC configuration and rest of
>> calculation about delay will be from ramp-delay.
> This sounds more like the difference between typical and maximum spec
> values than anything else, we are looking for maxima in Linux.
>

Maxim datasheet does not say about the typical/maximum. It has only one 
value and that is typical.
However, it has note on the advertised values as:

Note 20.
During a soft-start event or a DVS transition, the regulators output 
current will increase by COUT*dV/dt. In the event that the load current 
plus the additional current imposed by the soft-start or DVS transition, 
reach the regulators current limit, the current limit will be enforced. 
When the current limit is enforced, the advertised transition rate 
(dV/dt) will not occur.