From mboxrd@z Thu Jan 1 00:00:00 1970 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754409AbeAIKNm (ORCPT + 1 other); Tue, 9 Jan 2018 05:13:42 -0500 Received: from metis.ext.4.pengutronix.de ([92.198.50.35]:53413 "EHLO metis.ext.4.pengutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754613AbeAIKNc (ORCPT ); Tue, 9 Jan 2018 05:13:32 -0500 Message-ID: <1515492803.12538.29.camel@pengutronix.de> Subject: Re: [PATCH 1/7] ARM: imx: add timer stop flag to ARM power off state From: Lucas Stach To: Anson Huang , Dong Aisheng , Stefan Agner Cc: "mark.rutland@arm.com" , "devicetree@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "robh+dt@kernel.org" , dl-linux-imx , "kernel@pengutronix.de" , Fabio Estevam , "shawnguo@kernel.org" , "linux-arm-kernel@lists.infradead.org" Date: Tue, 09 Jan 2018 11:13:23 +0100 In-Reply-To: References: <20180102164223.15230-1-stefan@agner.ch> <20180109092232.GA26312@b29396-OptiPlex-7040> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.22.6-1+deb9u1 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit X-SA-Exim-Connect-IP: 2001:67c:670:100:fa0f:41ff:fe58:4010 X-SA-Exim-Mail-From: l.stach@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-kernel@vger.kernel.org Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: Am Dienstag, den 09.01.2018, 09:25 +0000 schrieb Anson Huang: > > Best Regards! > Anson Huang > > > > -----Original Message----- > > From: Dong Aisheng [mailto:dongas86@gmail.com] > > Sent: 2018-01-09 5:23 PM > > To: Stefan Agner > > Cc: shawnguo@kernel.org; kernel@pengutronix.de; Fabio Estevam > > ; robh+dt@kernel.org; mark.rutland@arm.com; > > linux-arm-kernel@lists.infradead.org; devicetree@vger.kernel.org; > > linux- > > kernel@vger.kernel.org; Anson Huang ; dl- > > linux-imx > > > > Subject: Re: [PATCH 1/7] ARM: imx: add timer stop flag to ARM power > > off state > > > > On Tue, Jan 02, 2018 at 05:42:17PM +0100, Stefan Agner wrote: > > > When the CPU is in ARM power off state the ARM architected timers > > > are > > > stopped. The flag is already present in the higher power WAIT > > > mode. > > > > > > This allows to use the ARM generic timer on i.MX 6UL/6ULL SoC. > > > Without the flag the kernel freezes when the timer enters the > > > first > > > time ARM power off mode. > > > > > > Cc: Anson Huang > > > Signed-off-by: Stefan Agner > > > > It seems ok at my side. > > Did you meet the real issue? If yes, how to reproduce? > > > > Both mx6sx and mx6ul are using GPT which do not need that flag, > > suppose we > > should remove it, right? > > Anson can help confirm it. > > For UP system like i.MX6SX, we do NOT enable "cortex-a9-twd-timer", > so local > timer is NOT used, GPT is used instead, GPT's clock is NOT disabled > when cpuidle, > so I think we should remove all these Timer stop flag for 6SX > CPUIDLE. It's correct to set the flag even on UP systems, as the flag means the CPU _local_ timer is stopped in this sleep mode. Also there are systems out there which are using the TWD on UP, as it operates at a higher frequency leading to better wakeup granularity. Regards, Lucas