Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751958Ab3CAJay (ORCPT ); Fri, 1 Mar 2013 04:30:54 -0500 Received: from hqemgate04.nvidia.com ([216.228.121.35]:8502 "EHLO hqemgate04.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751370Ab3CAJax (ORCPT ); Fri, 1 Mar 2013 04:30:53 -0500 X-PGP-Universal: processed; by hqnvupgp07.nvidia.com on Fri, 01 Mar 2013 01:30:51 -0800 Message-ID: <1362130891.19498.12.camel@bilhuang-vm1> Subject: Re: [PATCH 2/5] clk: notifier handler for dynamic voltage scaling From: Bill Huang To: Mike Turquette CC: "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "patches@linaro.org" , "linaro-dev@lists.linaro.org" Date: Fri, 1 Mar 2013 01:41:31 -0800 In-Reply-To: <1362026969-11457-3-git-send-email-mturquette@linaro.org> References: <1362026969-11457-1-git-send-email-mturquette@linaro.org> <1362026969-11457-3-git-send-email-mturquette@linaro.org> X-Mailer: Evolution 3.2.3-0ubuntu6 MIME-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-9" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1228 Lines: 28 On Thu, 2013-02-28 at 12:49 +0800, Mike Turquette wrote: > Dynamic voltage and frequency scaling (dvfs) is a common power saving > technique in many of today's modern processors. This patch introduces a > common clk rate-change notifier handler which scales voltage > appropriately whenever clk_set_rate is called on an affected clock. I really think clk_enable and clk_disable should also be triggering notifier call and DVFS should act accordingly since there are cases drivers won't set clock rate but instead disable its clock directly, do you agree? > > There are three prerequisites to using this feature: > > 1) the affected clocks must be using the common clk framework > 2) voltage must be scaled using the regulator framework > 3) clock frequency and regulator voltage values must be paired via the > OPP library Just a note, Tegra Core won't meet prerequisite #3 since each regulator voltage values is associated with clocks driving those many sub-HW blocks in it. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/