From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753190Ab2D0FjN (ORCPT ); Fri, 27 Apr 2012 01:39:13 -0400 Received: from na3sys009aog119.obsmtp.com ([74.125.149.246]:59287 "EHLO na3sys009aog119.obsmtp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751112Ab2D0FjM convert rfc822-to-8bit (ORCPT ); Fri, 27 Apr 2012 01:39:12 -0400 MIME-Version: 1.0 In-Reply-To: <20120426191159.GA9415@sirena.org.uk> References: <1335462041-4949-1-git-send-email-j-keerthy@ti.com> <20120426191159.GA9415@sirena.org.uk> Date: Fri, 27 Apr 2012 11:09:10 +0530 Message-ID: Subject: Re: [PATCH V3 00/10] PM: Create the AVS(Adaptive Voltage Scaling) From: "J, KEERTHY" To: Mark Brown Cc: linux-omap@vger.kernel.org, linux-arm-kernel@lists.infradead.org, khilman@ti.com, rjw@sisk.pl, linux-kernel@vger.kernel.org, linux-pm@lists.linux-foundation.org, j-pihet@ti.com Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello Mark, On Fri, Apr 27, 2012 at 12:41 AM, Mark Brown wrote: > On Thu, Apr 26, 2012 at 11:10:31PM +0530, Keerthy wrote: >> From: J Keerthy >> >> AVS(Adaptive Voltage Scaling) is a power management technique which >> controls the operating voltage of a device in order to optimize (i.e. reduce) >> its power consumption. The voltage is adapted depending on static factors >> (chip manufacturing process) and dynamic factors (temperature >> depending performance). >> The TI AVS solution is named Smartreflex. > > What's the relationship between this and existing things like devfreq > and cpufreq?  It'd be better if the changelogs made this clear and > provided an overview of how all these different subsystems are intended > to fit together. Devfreq and cpufreq are related to dynamic frequency/voltage switching between pre defined Operating Performance Points or the OPPs. Every OPP being a voltage/frequency pair. Smartreflex is a different power management technique. SmartReflex is a technology that uses adaptive power supply to achieve the goal of reducing active power consumption. With SmartReflex, the power supply voltage can be adapted to the silicon performance either statically (for example, adapted to the manufacturing process of a given device), or dynamically (for example, adapted to the temperature induced current performance of the device). So for every OPP(voltage/frequency pair) depending on the silicon process and temperature the Smartreflex tries to get the voltage to an optimal value at which the corresponding frequency can be sustained. -- Regards and Thanks, Keerthy