Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755622Ab2FFKS1 (ORCPT ); Wed, 6 Jun 2012 06:18:27 -0400 Received: from ch1ehsobe004.messaging.microsoft.com ([216.32.181.184]:35295 "EHLO ch1outboundpool.messaging.microsoft.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751199Ab2FFKS0 (ORCPT ); Wed, 6 Jun 2012 06:18:26 -0400 X-Forefront-Antispam-Report: CIP:70.37.183.190;KIP:(null);UIP:(null);IPV:NLI;H:mail.freescale.net;RD:none;EFVD:NLI X-SpamScore: -11 X-BigFish: VS-11(zzbb2dI9371I1432N98dKzz1202hzzz2dh2a8h668h839h944hd25hf0ah) Date: Wed, 6 Jun 2012 18:19:03 +0800 From: Zhao Chenhui To: Scott Wood CC: , , , Subject: Re: [PATCH v5 5/5] powerpc/85xx: add support to JOG feature using cpufreq interface Message-ID: <20120606101903.GC23505@localhost.localdomain> References: <1336737235-15370-1-git-send-email-chenhui.zhao@freescale.com> <1336737235-15370-5-git-send-email-chenhui.zhao@freescale.com> <4FC950AF.90007@freescale.com> <20120605105929.GA22427@localhost.localdomain> <4FCE2CB1.5090308@freescale.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <4FCE2CB1.5090308@freescale.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-OriginatorOrg: freescale.net Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1515 Lines: 44 On Tue, Jun 05, 2012 at 10:58:41AM -0500, Scott Wood wrote: > On 06/05/2012 05:59 AM, Zhao Chenhui wrote: > > On Fri, Jun 01, 2012 at 06:30:55PM -0500, Scott Wood wrote: > >> On 05/11/2012 06:53 AM, Zhao Chenhui wrote: > >>> The jog mode frequency transition process on the MPC8536 is similar to > >>> the deep sleep process. The driver need save the CPU state and restore > >>> it after CPU warm reset. > >>> > >>> Note: > >>> * The I/O peripherals such as PCIe and eTSEC may lose packets during > >>> the jog mode frequency transition. > >> > >> That might be acceptable for eTSEC, but it is not acceptable to lose > >> anything on PCIe. Especially not if you're going to make this "default y". > > > > It is a hardware limitation. > > Then make sure jog isn't used if PCIe is used. > > Maybe you could do something with the suspend infrastructure, but this > is sufficiently heavyweight that transitions should be manually > requested, not triggered by the automatic cpufreq governor. > > Does this apply to p1022, or just mpc8536? Both of them. > > > Peripherals in the platform will not be operating > > during the jog mode frequency transition process. > > What ensures this? > > -Scott Hardware ensures it without software intervention. -Chenhui -- 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/