Message-ID: <56FD6CF7.5080909@nvidia.com>
Date: Fri, 1 Apr 2016 00:01:19 +0530
From: Laxman Dewangan <ldewangan@nvidia.com>
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To: Mark Brown <broonie@kernel.org>
CC: Bjorn Andersson <bjorn@kryo.se>,
        Bjorn Andersson <bjorn.andersson@linaro.org>,
        Rob Herring <robh+dt@kernel.org>, Pawel Moll <pawel.moll@arm.com>,
        Mark Rutland <mark.rutland@arm.com>,
        Ian Campbell <ijc+devicetree@hellion.org.uk>,
        Liam Girdwood <lgirdwood@gmail.com>,
        "Stephen Warren" <swarren@wwwdotorg.org>,
        "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Gandhar Dighe <gdighe@nvidia.com>, "Stuart Yates" <syates@nvidia.com>
Subject: Re: [PATCH 1/2] regulator: DT: Add support to scale ramp delay based
 on platform behavior
References: <56E81103.8010903@nvidia.com> <CAJAp7OgUjN+Ymh+vM8g9Wex0JDRSOFkvpTKHm8fXYkDgTQ+0Tw@mail.gmail.com> <56ED0F58.7060005@nvidia.com> <56FBD4A3.7080208@nvidia.com> <20160330181623.GQ2350@sirena.org.uk> <56FCCC60.3080303@nvidia.com> <20160331165145.GF2350@sirena.org.uk> <56FD5A9F.5050001@nvidia.com> <20160331174741.GO2350@sirena.org.uk> <56FD62BA.3040406@nvidia.com> <20160331183130.GR2350@sirena.org.uk>
In-Reply-To: <20160331183130.GR2350@sirena.org.uk>
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On Friday 01 April 2016 12:01 AM, Mark Brown wrote:
> * PGP Signed by an unknown key
>
> On Thu, Mar 31, 2016 at 11:17:38PM +0530, Laxman Dewangan wrote:
>
>> HW and chip team did simulation with tegra and PMIC and found that the board
>> needs more capacitance then what Vendor recommended for proper signal
>> conditioning on interface. So they put the difference capactitance value and
>> this causes deviation in ramp delay from advertised value. In out design, we
>> measured the ramp time as 50mv/us when PMIC is configured for 100mV/us.
>> So for all settling time, we need to use the ramp as 50mV/us.
>>  From DT, I will provide regulator-ramp-delay as 50mv/us.
>> But I do not have property for saying 100mv/us for PMIC configurations and
>> this is what makes need of 2nd property.
> So the PMIC actually has a setting for the rate you're seeing but for
> some resaon you can't use it?

PMIC has the different rate setting what I am seeing on platform (measured).
HW team measured the ramp dealy with specific configuration of rate 
setting on PMIC which is not default (OTP-One time programmed from Vendor).