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Date:   Wed, 27 Dec 2017 00:54:00 +0000
From:   Peng Fan <peng.fan@....com>
To:     Dong Aisheng <dongas86@...il.com>
CC:     Shawn Guo <shawnguo@...nel.org>,
        "A.s. Dong" <aisheng.dong@....com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Russell King <linux@...linux.org.uk>,
        Fabio Estevam <fabio.estevam@....com>,
        Sascha Hauer <kernel@...gutronix.de>,
        "van.freenix@...il.com" <van.freenix@...il.com>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>
Subject: RE: [PATCH] arm: imx: suspend/resume: use outer_disable/resume



> -----Original Message-----
> From: Dong Aisheng [mailto:dongas86@...il.com]
> Sent: Tuesday, December 26, 2017 6:21 PM
> To: Peng Fan <peng.fan@....com>
> Cc: Shawn Guo <shawnguo@...nel.org>; A.s. Dong <aisheng.dong@....com>;
> linux-kernel@...r.kernel.org; Russell King <linux@...linux.org.uk>; Fabio
> Estevam <fabio.estevam@....com>; Sascha Hauer <kernel@...gutronix.de>;
> van.freenix@...il.com; linux-arm-kernel@...ts.infradead.org
> Subject: Re: [PATCH] arm: imx: suspend/resume: use outer_disable/resume
> 
> On Tue, Dec 26, 2017 at 10:11:41AM +0000, Peng Fan wrote:
> >
> > Hi Aisheng,
> >
> > > -----Original Message-----
> > > From: Dong Aisheng [mailto:dongas86@...il.com]
> > > Sent: Tuesday, December 26, 2017 6:04 PM
> > > To: Peng Fan <peng.fan@....com>
> > > Cc: Shawn Guo <shawnguo@...nel.org>; A.s. Dong
> > > <aisheng.dong@....com>; linux-kernel@...r.kernel.org; Russell King
> > > <linux@...linux.org.uk>; Fabio Estevam <fabio.estevam@....com>;
> > > Sascha Hauer <kernel@...gutronix.de>; van.freenix@...il.com;
> > > linux-arm-kernel@...ts.infradead.org
> > > Subject: Re: [PATCH] arm: imx: suspend/resume: use
> > > outer_disable/resume
> > >
> > > On Tue, Dec 26, 2017 at 09:49:01AM +0000, Peng Fan wrote:
> > > > Hi Shawn
> > > >
> > > > > -----Original Message-----
> > > > > From: Shawn Guo [mailto:shawnguo@...nel.org]
> > > > > Sent: Tuesday, December 26, 2017 5:13 PM
> > > > > To: Peng Fan <peng.fan@....com>
> > > > > Cc: A.s. Dong <aisheng.dong@....com>;
> > > > > linux-kernel@...r.kernel.org; Russell King
> > > > > <linux@...linux.org.uk>; Fabio Estevam <fabio.estevam@....com>;
> > > > > Sascha Hauer <kernel@...gutronix.de>; van.freenix@...il.com;
> > > > > linux-arm- kernel@...ts.infradead.org
> > > > > Subject: Re: [PATCH] arm: imx: suspend/resume: use
> > > > > outer_disable/resume
> > > > >
> > > > > On Sun, Dec 10, 2017 at 08:07:18PM +0800, Peng Fan wrote:
> > > > > > Use outer_disable/resume for suspend/resume.
> > > > > > With the two APIs used, code could be simplified and easy to
> > > > > > extend to introduce l2c_write_sec for i.MX platforms when
> > > > > > moving Linux Kernel runs in non-secure world.
> > > > > >
> > > > > > Signed-off-by: Peng Fan <peng.fan@....com>
> > > > > > Cc: Shawn Guo <shawnguo@...nel.org>
> > > > > > Cc: Sascha Hauer <kernel@...gutronix.de>
> > > > > > Cc: Fabio Estevam <fabio.estevam@....com>
> > > > > > Cc: Russell King <linux@...linux.org.uk>
> > > > > > Cc: Dong Aisheng <aisheng.dong@....com>
> > > > >
> > > > > Changed 'arm: ' prefix to 'ARM: ', and applied patch.
> > > >
> > > > I just tested it on 6sx-sdb, seems this patch breaks 6sx. Could
> > > > you first drop this patch? I'll send out v2 fix the 6sx issue soon.
> > > >
> > >
> > > Yes, i tested mx6ul/mx6sl ok but mx6sx sdb failed.
> >
> > Thanks for the test.
> >
> > >
> > > After a few debug, it seems you removed the l2c310_early_resume in
> > > v7_cpu_resume which is shared between lower power idle and suspend.
> > >
> > > Current only mx6sx/mx6ul supports low power idle in upstream, but
> > > mx6ul is
> > > A7 with internal L2, that's probably why only mx6sx showed the issue.
> > >
> > > I did the following quick try to restore L2 after exit lower power
> > > idle, but still can meet occasional crash during booting.
> > >
> > > diff --git a/arch/arm/mach-imx/cpuidle-imx6sx.c b/arch/arm/mach-
> > > imx/cpuidle-imx6sx.c index c5a5c3a..edce5bd 100644
> > > --- a/arch/arm/mach-imx/cpuidle-imx6sx.c
> > > +++ b/arch/arm/mach-imx/cpuidle-imx6sx.c
> > > @@ -26,7 +26,7 @@ static int imx6sx_idle_finish(unsigned long val)
> > >          * to adding conditional code for L2 cache type,
> > >          * just call flush_cache_all() is fine.
> > >          */
> > > -       flush_cache_all();
> > > +//     flush_cache_all();
> >
> > I think flush_cache_all is still needed, to flush L1 data, right?
> >
> 
> I thought it will be done in generic cpu_suspend.
> See: __cpu_suspend_save()
> 
> So we still need it?

After remove flush_cache_all, seems 6sx-sdb suspend/resume and low power idle both works.
Alought __cpu_suspend_save flush data, my understanding is there is chance to cache data/inst
before "wfi". Then we better keep flush_cache_all here?

Thanks,
Peng.

> 
> 
> Regards
> Dong Aisheng
> > >         cpu_do_idle();
> > >
> > >         return 0;
> > > @@ -49,7 +49,9 @@ static int imx6sx_enter_wait(struct cpuidle_device
> *dev,
> > >                 cpu_pm_enter();
> > >                 cpu_cluster_pm_enter();
> > >
> > > +               outer_disable();
> > >                 cpu_suspend(0, imx6sx_idle_finish);
> > > +               outer_resume();
> >
> > Yes, this is in my V2 patch.
> >
> > >
> > >                 cpu_cluster_pm_exit();
> > >                 cpu_pm_exit();
> > >
> > > As this changed the order to L2 restore and cpu resume, so i'm not
> > > quite sure if lower power idle still requres L2 restore before CPU
> > > resume or something else we're missing.
> >
> > In low power idle, L2 may also lose power, so outer_disable/resume is
> needed, I think.
> >
> > Thanks,
> > Peng.
> >
> > >
> > > Regards
> > > Dong Aisheng
> > >
> > > > Thanks,
> > > > Peng.
> > > >
> > > > >
> > > > > Shawn

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