Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759328AbXETQC6 (ORCPT ); Sun, 20 May 2007 12:02:58 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757355AbXETQCu (ORCPT ); Sun, 20 May 2007 12:02:50 -0400 Received: from mail-in-03.arcor-online.net ([151.189.21.43]:52798 "EHLO mail-in-03.arcor-online.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756518AbXETQCt (ORCPT ); Sun, 20 May 2007 12:02:49 -0400 In-Reply-To: <1179630190.32247.534.camel@localhost.localdomain> References: <200705172142.26739.sshtylyov@ru.mvista.com> <8E44DB06-767D-4864-8D2C-6132E4D4370B@kernel.crashing.org> <464C99FF.8080404@ru.mvista.com> <135307ED-7125-4859-8594-4B5B900D92D6@kernel.crashing.org> <1179500217.20519.53.camel@imap.mvista.com> <464DC0DC.7050809@ru.mvista.com> <1179502773.20519.56.camel@imap.mvista.com> <17998.28659.702653.237011@cargo.ozlabs.ibm.com> <1179628991.20925.2.camel@imap.mvista.com> <1179630190.32247.534.camel@localhost.localdomain> Mime-Version: 1.0 (Apple Message framework v623) Content-Type: text/plain; charset=US-ASCII; format=flowed Message-Id: <995a4a7a4cada5604be7b30dcce8eb81@kernel.crashing.org> Content-Transfer-Encoding: 7bit Cc: Paul Mackerras , linux-kernel@vger.kernel.org, mingo@elte.hu, Daniel Walker , linuxppc-dev@ozlabs.org, tglx@linutronix.de From: Segher Boessenkool Subject: Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver Date: Sun, 20 May 2007 18:02:46 +0200 To: Benjamin Herrenschmidt X-Mailer: Apple Mail (2.623) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 954 Lines: 27 > In fact, while it's never worded explicitely in the spec, it's always > been strongly in the "spirit" of the architecture that the timebase and > decrementer have a constant frequency. The architecture mentions varying time base frequencies, and how to deal with this, actually. It makes no recommendations one way or the other. Fixed frequencies are easier for almost everything of course :-) > This is why processors like the > 970 allow for an external sourcing for when they are used in setups > where the various clocks are slewed for power management. Clock spreading on the core clock is the bigger problem, lack of accuracy on the order of 1% is unacceptable for certain applications. Segher - 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/