linux-kernel - RE: [PATCH] arm: imx: suspend/resume: use outer

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Message-ID: <DB6PR04MB3221FC8A0E2D6980F8AAB1A288060@DB6PR04MB3221.eurprd04.prod.outlook.com>
Date:   Tue, 26 Dec 2017 10:11:41 +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


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?

>         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