Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758031AbXERNoP (ORCPT ); Fri, 18 May 2007 09:44:15 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755018AbXERNoD (ORCPT ); Fri, 18 May 2007 09:44:03 -0400 Received: from h155.mvista.com ([63.81.120.155]:31202 "EHLO imap.sh.mvista.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1755176AbXERNoA (ORCPT ); Fri, 18 May 2007 09:44:00 -0400 Message-ID: <464DADFC.3080802@ru.mvista.com> Date: Fri, 18 May 2007 17:45:32 +0400 From: Sergei Shtylyov Organization: MontaVista Software Inc. User-Agent: Mozilla/5.0 (X11; U; Linux i686; rv:1.7.2) Gecko/20040803 X-Accept-Language: ru, en-us, en-gb MIME-Version: 1.0 To: Matt Sealey 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> <464D9E7E.3090605@genesi-usa.com> In-Reply-To: <464D9E7E.3090605@genesi-usa.com> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1412 Lines: 40 Hello. Matt Sealey 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? If you have some SoC timers, you're welcome to add support for it. :-) > I guess the real question is, how high resolution does a high resolution > timer need to be, In the order of microseconds. > and how often do you want to be handling interrupts? That depends on a kind of functionality you need: HRT and/or dynamic tick... > 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.. WBR, Sergei - 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/