From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Cousson, Benoit" Subject: Re: [RFC/PATCH 00/26] PM: Create the AVS class of drivers Date: Tue, 22 Nov 2011 18:40:07 +0100 Message-ID: <4ECBDE77.6000703@ti.com> References: <1321974370-25800-1-git-send-email-j-pihet@ti.com> <20111122164302.GI6624@sirena.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from devils.ext.ti.com ([198.47.26.153]:34535 "EHLO devils.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751668Ab1KVRkZ (ORCPT ); Tue, 22 Nov 2011 12:40:25 -0500 In-Reply-To: <20111122164302.GI6624@sirena.org.uk> Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: Mark Brown Cc: jean.pihet@newoldbits.com, Linux OMAP Mailing List , paul@pwsan.com, khilman@ti.com, balbi@ti.com, rjw@sisk.pl, Jean Pihet Hi Mark, On 11/22/2011 5:43 PM, Mark Brown wrote: > On Tue, Nov 22, 2011 at 04:05:44PM +0100, jean.pihet@newoldbits.com wrote: > >> AVS 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). >> AVS is also called SmartReflex on OMAP devices. > > This sounds a lot like what devfreq (which was recently merged) is > supposed to do. Have you looked at the overlap there? devfreq is a fmwk for DVFS governors at device level, whereas AVS stands for Adaptive Voltage Scaling. This technique does not involve any frequency change, and does a fine voltage adjustment to adapt to silicon process / aging / thermal variation based on a HW closed loop. Both DVFS and AVS can be used independently. I think that AVS does belong to the voltage control infrastructure more than the DVFS/freq one. But that just my .2 cents Regards, Benoit