Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756816AbXERMjT (ORCPT ); Fri, 18 May 2007 08:39:19 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754378AbXERMjN (ORCPT ); Fri, 18 May 2007 08:39:13 -0400 Received: from mithrandir.softwarenexus.net ([66.98.186.96]:1611 "EHLO mail.genesi-usa.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754338AbXERMjM (ORCPT ); Fri, 18 May 2007 08:39:12 -0400 Message-ID: <464D9E7E.3090605@genesi-usa.com> Date: Fri, 18 May 2007 13:39:26 +0100 From: Matt Sealey User-Agent: Thunderbird 2.0.0.0 (Windows/20070326) MIME-Version: 1.0 To: Sergei Shtylyov CC: Kumar Gala , 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 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> <464C9E67.2020909@ru.mvista.com> <6E0D5E13-C939-4FCE-81A3-F29DFA6436A2@kernel.crashing.org> <464CA222.8000407@ru.mvista.com> In-Reply-To: <464CA222.8000407@ru.mvista.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1325 Lines: 37 Sergei Shtylyov wrote: > Hello. > > Kumar Gala wrote: > >>> Kumar Gala wrote: > >>>> I haven't looked at all the new clock/timer code, is there any >>>> utility in having support for more than one clock source? > >>> Of course, you may register as many as you like. > >> Sure, but is there any utility in registering more than the decrementer >> on PPC? > > Not yet. I'm not sure I know any other PPC CPU facility fitting for > clockevents. In theory, FIT could be used -- but its period is measured in > powers of 2, IIRC. Wouldn't it be possible to use SoC timer functionality, too, and not limit this to what is only present on the CPU die? I guess the real question is, how high resolution does a high resolution timer need to be, and how often do you want to be handling interrupts? The 52XX has 8 general purpose timers and 2 slice timers. Both will generate an interrupt once the clock hits a preset value, the timing of which is determined by prescalers and the IPB clock.. -- Matt Sealey Genesi, Manager, Developer Relations - 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/