Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758808Ab2BKOxT (ORCPT ); Sat, 11 Feb 2012 09:53:19 -0500 Received: from merlin.infradead.org ([205.233.59.134]:40301 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754254Ab2BKOxS (ORCPT ); Sat, 11 Feb 2012 09:53:18 -0500 Subject: Re: [PATCH RFC 0/4] Scheduler idle notifiers and users From: Peter Zijlstra To: Mark Brown Cc: Saravana Kannan , Ingo Molnar , Benjamin Herrenschmidt , Todd Poynor , Russell King , Nicolas Pitre , Oleg Nesterov , cpufreq@vger.kernel.org, linux-kernel@vger.kernel.org, Anton Vorontsov , linaro-kernel@lists.linaro.org, Mike Chan , Dave Jones , "Paul E. McKenney" , kernel-team@android.com, linux-arm-kernel@lists.infradead.org, Arjan Van De Ven In-Reply-To: <20120211143951.GA24564@sirena.org.uk> References: <20120208013959.GA24535@panacea> <1328670355.2482.68.camel@laptop> <20120208202314.GA28290@redhat.com> <1328736834.2903.33.camel@pasglop> <20120209075106.GB18387@elte.hu> <4F35DD3E.4020406@codeaurora.org> <20120211143951.GA24564@sirena.org.uk> Content-Type: text/plain; charset="UTF-8" Date: Sat, 11 Feb 2012 15:53:03 +0100 Message-ID: <1328971983.11320.5.camel@laptop> Mime-Version: 1.0 X-Mailer: Evolution 2.32.2 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 878 Lines: 19 On Sat, 2012-02-11 at 14:39 +0000, Mark Brown wrote: > > For step downs this isn't such a big deal as we don't often care if the > voltage drops immediately but for step ups it's critical as if the > voltage hasn't ramped before the CPU tries to run at the higher > frequency the CPU will brown out. Why isn't all this done by micro-controllers, software writes a desired state in some machine register (fast), micro-controller sets about making it so in an asynchronous way. If it finds the settings have changed by the time it reached its former goal, goto 1. Having to actually wait for this in software is quite ridiculous. -- 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/