linux-kernel - Re: [v3,4/5] powerpc/pm: support deep sleep feature on T104x

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Message-ID: <1475515377.4917.7.camel@buserror.net>
Date:   Mon, 03 Oct 2016 12:22:57 -0500
From:   Scott Wood <oss@...error.net>
To:     "C.H. Zhao" <chenhui.zhao@....com>
Cc:     "linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "z.chenhui@...il.com" <z.chenhui@...il.com>,
        Jason Jin <jason.jin@....com>
Subject: Re: [v3,4/5] powerpc/pm: support deep sleep feature on T104x

On Thu, 2016-09-29 at 10:21 +0000, C.H. Zhao wrote:
> 
> From: Scott Wood <oss@...error.net>
> Sent: Thursday, September 29, 2016 4:03 AM
> To: C.H. Zhao
> Cc: linuxppc-dev@...ts.ozlabs.org; linux-kernel@...r.kernel.org; z.chenhui@g
> mail.com; Jason Jin
> Subject: Re: [v3,4/5] powerpc/pm: support deep sleep feature on T104x
>     
> On Tue, 2016-09-27 at 11:05 +0000, C.H. Zhao wrote:
> > 
> > From: Scott Wood <oss@...error.net>
> > Sent: Sunday, September 25, 2016 3:24 PM
> > To: C.H. Zhao
> > Cc: linuxppc-dev@...ts.ozlabs.org; linux-kernel@...r.kernel.org; z.chenhui
> > @g
> > mail.com; Jason Jin
> > Subject: Re: [v3,4/5] powerpc/pm: support deep sleep feature on T104x
> >     
> > On Tue, Aug 02, 2016 at 07:59:31PM +0800, Chenhui Zhao wrote:
> > > 
> > > 
> > > T104x has deep sleep feature, which can switch off most parts of
> > > the SoC when it is in deep sleep mode. This way, it becomes more
> > > energy-efficient.
> > > 
> > > The DDR controller will also be powered off in deep sleep. Therefore,
> > > the last stage (the latter part of fsl_dp_enter_low) will run without
> > > DDR
> > > access. This piece of code and related TLBs are prefetched in advance.
> > > 
> > > Due to the different initialization code between 32-bit and 64-bit, they
> > > have separate resume entry and precedure.
> > > 
> > > The feature supports 32-bit and 64-bit kernel mode.
> > > 
> > > Signed-off-by: Chenhui Zhao <chenhui.zhao@....com>
> > > ---
> > >   arch/powerpc/include/asm/fsl_pm.h             |  24 ++
> > >   arch/powerpc/kernel/asm-offsets.c             |  12 +
> > >   arch/powerpc/kernel/fsl_booke_entry_mapping.S |  10 +
> > >   arch/powerpc/kernel/head_64.S                 |   2 +-
> > >   arch/powerpc/platforms/85xx/Makefile          |   1 +
> > >   arch/powerpc/platforms/85xx/deepsleep.c       | 278 ++++++++++++++
> > >   arch/powerpc/platforms/85xx/qoriq_pm.c        |  25 ++
> > >   arch/powerpc/platforms/85xx/t104x_deepsleep.S | 531
> > > ++++++++++++++++++++++++++
> > >   arch/powerpc/sysdev/fsl_rcpm.c                |   8 +-
> > >   9 files changed, 889 insertions(+), 2 deletions(-)
> > >   create mode 100644 arch/powerpc/platforms/85xx/deepsleep.c
> > >   create mode 100644 arch/powerpc/platforms/85xx/t104x_deepsleep.S
> > > 
> > > diff --git a/arch/powerpc/include/asm/fsl_pm.h
> > > b/arch/powerpc/include/asm/fsl_pm.h
> > > index e05049b..48c2631 100644
> > > --- a/arch/powerpc/include/asm/fsl_pm.h
> > > +++ b/arch/powerpc/include/asm/fsl_pm.h
> > > @@ -20,6 +20,7 @@
> > >   
> > >   #define PLAT_PM_SLEEP        20
> > >   #define PLAT_PM_LPM20        30
> > > +#define PLAT_PM_LPM35        40
> > >   
> > >   #define FSL_PM_SLEEP         (1 << 0)
> > >   #define FSL_PM_DEEP_SLEEP    (1 << 1)
> > > @@ -48,4 +49,27 @@ extern const struct fsl_pm_ops *qoriq_pm_ops;
> > >   
> > >   int __init fsl_rcpm_init(void);
> > >   
> > > +#ifdef CONFIG_FSL_QORIQ_PM
> > > +int fsl_enter_deepsleep(void);
> > > +int fsl_deepsleep_init(void);
> > > +#else
> > > +static inline int fsl_enter_deepsleep(void) { return -1; }
> > > +static inline int fsl_deepsleep_init(void) { return -1; }
> > > +#endif
> > Please return proper error codes.
> > 
> > Where can fsl_deepsleep_init() be called without CONFIG_FSL_QORIQ_PM?
> > 
> > [Chenhui] I can get rid of the ifdef here. And add it
> > in arch/powerpc/sysdev/fsl_rcpm.c.
> No, this is the right place for the ifdef for functions that are called from
> code that doesn't depend on CONFIG_FSL_QORIQ_PM.  But fsl_deepsleep_init()
> is
> called from deepsleep.c which is only built with CONFIG_FSL_QORIQ_PM, and
> it's
> hard to picture a scenario where it would be called from elsewhere.
> 
> 
> [Chenhui] You are right. No need to enclose fsl_deepsleep_init() in the
> ifdef.
>                  But regarding fsl_enter_deepsleep(), it is called in
> rcpm_v2_plat_enter_sleep()
>                  in arch/powerpc/sysdev/fsl_rcpm.c. It still needs to be
> enclosed in the ifdef.

Right.  That's why I specifically asked about fsl_deepsleep_init(). :-)

-Scott