From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lucas Stach Subject: Re: [PATCH 1/7] ARM: imx: add timer stop flag to ARM power off state Date: Tue, 09 Jan 2018 11:13:23 +0100 Message-ID: <1515492803.12538.29.camel@pengutronix.de> References: <20180102164223.15230-1-stefan@agner.ch> <20180109092232.GA26312@b29396-OptiPlex-7040> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org 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" List-Id: devicetree@vger.kernel.org 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