From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752830Ab1GFLFw (ORCPT ); Wed, 6 Jul 2011 07:05:52 -0400 Received: from mail-ww0-f44.google.com ([74.125.82.44]:37894 "EHLO mail-ww0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752591Ab1GFLFu (ORCPT ); Wed, 6 Jul 2011 07:05:50 -0400 Date: Wed, 6 Jul 2011 12:05:48 +0100 From: Catalin Marinas To: Russell King - ARM Linux Cc: Marc Zyngier , Vitaly Kuzmichev , "linux-arm-kernel@lists.infradead.org" , "linux-watchdog@vger.kernel.org" , Wim Van Sebroeck , "arm@kernel.org" , "linux-kernel@vger.kernel.org" , Arnd Bergmann , John Stultz , Nicolas Pitre , Thomas Gleixner Subject: Re: [PATCH V2 0/6] arm_smp_twd: mpcore_wdt: Fix MPCORE watchdog setup Message-ID: <20110706110548.GA31936@1n450.cable.virginmedia.net> References: <1286185540-19569-1-git-send-email-vkuzmichev@mvista.com> <1309892440-3260-1-git-send-email-vkuzmichev@mvista.com> <4E14337F.1050101@arm.com> <20110706101456.GN8286@n2100.arm.linux.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110706101456.GN8286@n2100.arm.linux.org.uk> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org (sorry for reposting - did something wrong with the SMTP configuration and the original mail was rejected as spam by most recipients) On Wed, Jul 06, 2011 at 11:14:56AM +0100, Russell King - ARM Linux wrote: > On Wed, Jul 06, 2011 at 11:05:51AM +0100, Marc Zyngier wrote: > > On 05/07/11 20:00, Vitaly Kuzmichev wrote: > > > The series of patches fixes various bugs in ARM MPCORE watchdog setup. > > > They also introduce some changes in common ARM_SMP_TWD timer setup code. > > > The PATCH 2/6 adds an exported function to obtain twd timer rate in > > > mpcore_wdt. However, this solution might be unacceptable, and the > > > better is to copy calibration loop and clk_get_rate calling to mpcore_wdt. > > > > My take on this is that the calibration loop should simply be killed > > once Colin's patch using the "smp_twd" clock is merged and relevant > > platforms updated. Once this is done, the watchdog driver should use the > > clock directly, without exporting a symbol. > > Do we know why the calibration was initially introduced? FWIR, it came > from the SMP group in ARM, so I guess they had a reason for it rather > than copying x86. I think it was introduced because the TWD frequency is half of the CPU frequency but the latter may not be known - boot monitor configuration could change it. -- Catalin