From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758277AbXESDen (ORCPT ); Fri, 18 May 2007 23:34:43 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754761AbXESDeg (ORCPT ); Fri, 18 May 2007 23:34:36 -0400 Received: from ozlabs.org ([203.10.76.45]:52031 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754561AbXESDeg (ORCPT ); Fri, 18 May 2007 23:34:36 -0400 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-ID: <17998.28659.702653.237011@cargo.ozlabs.ibm.com> Date: Sat, 19 May 2007 13:33:07 +1000 From: Paul Mackerras To: Daniel Walker Cc: Sergei Shtylyov , linuxppc-dev@ozlabs.org, tglx@linutronix.de, mingo@elte.hu, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver In-Reply-To: <1179502773.20519.56.camel@imap.mvista.com> 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> X-Mailer: VM 7.19 under Emacs 21.4.1 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Daniel Walker writes: > On Fri, 2007-05-18 at 19:06 +0400, Sergei Shtylyov wrote: > > Well, the decrementer frequency may change, at least in theory (if the bus > > clock changes). > > Does that happen very often? If it did, gettimeofday would start reporting seriously wrong values, since the timebase and the decrementer count at the same rate, and we don't have any provision for fixing things up if that rate changed. Fortunately there are no powerpc platforms where the rate is variable. Paul.