From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755964Ab3IKR0G (ORCPT ); Wed, 11 Sep 2013 13:26:06 -0400 Received: from hqemgate15.nvidia.com ([216.228.121.64]:5741 "EHLO hqemgate15.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754958Ab3IKR0E (ORCPT ); Wed, 11 Sep 2013 13:26:04 -0400 X-PGP-Universal: processed; by hqnvupgp07.nvidia.com on Wed, 11 Sep 2013 10:26:02 -0700 Message-ID: <5230AC5E.2020504@nvidia.com> Date: Wed, 11 Sep 2013 23:16:06 +0530 From: Laxman Dewangan User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:16.0) Gecko/20121028 Thunderbird/16.0.2 MIME-Version: 1.0 To: Stephen Warren CC: "broonie@kernel.org" , "rob.herring@calxeda.com" , "mark.rutland@arm.com" , "rob@landley.net" , "devicetree@vger.kernel.org" , "linux-doc@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "lgirdwood@gmail.com" Subject: Re: [PATCH V2] regulator: core: add support for configuring turn-on time through constraints References: <1378904331-5665-1-git-send-email-ldewangan@nvidia.com> <5230A593.9010401@wwwdotorg.org> In-Reply-To: <5230A593.9010401@wwwdotorg.org> Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wednesday 11 September 2013 10:47 PM, Stephen Warren wrote: > On 09/11/2013 06:58 AM, Laxman Dewangan wrote: >> The Turn-on time of the regulator depends on the regulator device's >> electrical characteristics. Sometimes regulator turn-on time also >> depends on the capacitive load on the given platform and it can be >> more than the datasheet value. >> >> The driver provides the enable-time as per datasheet. >> >> Add support for configure the enable ramp time through regulator >> constraints so that regulator core can take this value for enable >> time for that regulator. >> diff --git a/Documentation/devicetree/bindings/regulator/regulator.txt b/Documentation/devicetree/bindings/regulator/regulator.txt >> - regulator-ramp-delay: ramp delay for regulator(in uV/uS) >> For hardwares which support disabling ramp rate, it should be explicitly >> intialised to zero (regulator-ramp-delay = <0>) for disabling ramp delay. >> +- regulator-enable-ramp-delay: Turn-on time for regulator(in uSec). This is >> + the time time taken to reach within some proportion of the target voltage >> + from off state. > This is still a bit unclear. What proportion of the target voltage? > There's no mention that this describes the delay due to the > board/environment rather than the delay due to the internal operation of > the regulator itself. How about: > > - regulator-enable-ramp-delay: The time taken, in uSec, for the supply > rail to reach the target voltage, plus/minus whatever tolerance the > board design requires, once the regulator output itself has ramped up. > This value is in addition to whatever built-in ramp time is inherent in > the regulator's own internal design or configuration. This property > describes the additional ramp time required due to board design issues > such as trace capacitance and load on the supply. > > That's text repeats "additional" a bit, but I think describes the > situation correctly? I wanted to provide the absolute delay rather than additional delay on top of inherit delay from device.