Am Dienstag, den 09.01.2018, 09:25 +0000 schrieb Anson Huang: > > Best Regards! > Anson Huang > > > > -----Original Message----- > > From: Dong Aisheng [mailto:[email protected]] > > Sent: 2018-01-09 5:23 PM > > To: Stefan Agner <[email protected]> > > Cc: [email protected]; [email protected]; Fabio Estevam > > <[email protected]>; [email protected]; [email protected]; > > [email protected]; [email protected]; > > linux- > > [email protected]; Anson Huang <[email protected]>; dl- > > linux-imx > > <[email protected]> > > 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 <[email protected]> > > > Signed-off-by: Stefan Agner <[email protected]> > > > > 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
