Re: [PATCH 01/02] ARM: shmobile: Add r8a73a4 SMP support using APMU code

[Olof Johansson <olof@lixom.net>]

[+khilman]

Hi,

On Wed, Aug 21, 2013 at 05:57:15PM +0900, Simon Horman wrote:
> On Thu, Aug 08, 2013 at 02:52:32PM +0900, Magnus Damm wrote:
> > Hi Arnd and Olof,
> > 
> > On Thu, Aug 8, 2013 at 7:55 AM, Magnus Damm <magnus.damm@gmail.com> wrote:
> > > From: Magnus Damm <damm@opensource.se>
> > >
> > > Add r8a73a4 SMP support using the shared APMU code. To enable
> > > SMP the r8a73a4 specific DTS needs to be updated to include
> > > CPU cores, and this is happening in a separate patch.
> > >
> > > Signed-off-by: Magnus Damm <damm@opensource.se>
> > > ---
> > >
> > >  arch/arm/mach-shmobile/Makefile               |    1
> > >  arch/arm/mach-shmobile/include/mach/r8a73a4.h |    1
> > >  arch/arm/mach-shmobile/setup-r8a73a4.c        |    3 +
> > >  arch/arm/mach-shmobile/smp-r8a73a4.c          |   75 +++++++++++++++++++++++++
> > >  4 files changed, 80 insertions(+)
> > >
> > > --- 0001/arch/arm/mach-shmobile/Makefile
> > > +++ work/arch/arm/mach-shmobile/Makefile        2013-08-07 20:07:31.000000000 +0900
> > > @@ -33,6 +33,7 @@ endif
> > >  # SMP objects
> > >  smp-y                          := platsmp.o headsmp.o
> > >  smp-$(CONFIG_ARCH_SH73A0)      += smp-sh73a0.o headsmp-scu.o platsmp-scu.o
> > > +smp-$(CONFIG_ARCH_R8A73A4)     += smp-r8a73a4.o platsmp-apmu.o
> > >  smp-$(CONFIG_ARCH_R8A7779)     += smp-r8a7779.o headsmp-scu.o platsmp-scu.o
> > >  smp-$(CONFIG_ARCH_EMEV2)       += smp-emev2.o headsmp-scu.o platsmp-scu.o
> > >
> > > --- 0008/arch/arm/mach-shmobile/include/mach/r8a73a4.h
> > > +++ work/arch/arm/mach-shmobile/include/mach/r8a73a4.h  2013-08-07 20:08:02.000000000 +0900
> > > @@ -6,5 +6,6 @@ void r8a73a4_add_dt_devices(void);
> > >  void r8a73a4_clock_init(void);
> > >  void r8a73a4_pinmux_init(void);
> > >  void r8a73a4_init_early(void);
> > > +extern struct smp_operations r8a73a4_smp_ops;
> > >
> > >  #endif /* __ASM_R8A73A4_H__ */
> > > --- 0008/arch/arm/mach-shmobile/setup-r8a73a4.c
> > > +++ work/arch/arm/mach-shmobile/setup-r8a73a4.c 2013-08-07 20:07:48.000000000 +0900
> > > @@ -212,6 +212,9 @@ void __init r8a73a4_init_early(void)
> > >  #ifndef CONFIG_ARM_ARCH_TIMER
> > >         shmobile_setup_delay(1500, 2, 4); /* Cortex-A15 @ 1500MHz */
> > >  #endif
> > > +#ifdef CONFIG_SMP
> > > +       smp_set_ops(&r8a73a4_smp_ops);
> > > +#endif
> > >  }
> > 
> > Arnd or Olof, may I ask for your advice here?
> > 
> > I think it's quite nice to use smp_set_ops() in ->init_early() to
> > install the per-SoC SMP operations. I prefer that over using the
> > smp_ops directly in the per-board DT_MACHINE_START. Which way do you
> > prefer?
> 
> Olof, Arnd, Ping.


Sorry, missed the original question when it was posted.

I guess I don't see the benefit of doing it in code vs smp_init? You
already have a DT_MACHINE section for r8a73a4 in this case.

If you use .smp_init = smp_init_ops(r8a73a4_smp_ops) then there's no
ifdef needed down in the DT_MACHINE section either.


-Olof