Re: [PATCH] keystone: adds cpu_die implementation

[Vitaly Andrianov]

On 06/29/2015 01:52 PM, Mark Rutland wrote:
> On Mon, Jun 29, 2015 at 06:52:32PM +0100, Vitaly Andrianov wrote:
> > This commit add cpu_die implementation
> >
> > Signed-off-by: Vitaly Andrianov <vitalya@xxxxxx>
> > ---
> >
> > The discussion of the "keystone: psci: adds cpu_die implementation" commit
> > shows that if PCSI is enabled platform code doesn't need that implementation
> > at all. Having PSCI commands in DTB should be sufficient. Unfortunately
> > Keystone with LPAE enable requires some additional development.
>
> I don't follow.
>
> What do you need to implement for LPAE?
Hi Mark,

The Keystone platform needs to set ttbr1 when it boots secondary core.
It is done in the keystone_smp_secondary_initmem(), which is 
.smp_secondary_init member of the keystone_smp_ops. I couldn't find a 
way how I can add similar function to psci_smp_ops.

Do you have any idea?

> Why not implement that rather than adding more platform code that you'll
> likely want to remove later anyway?

If I can solve the above problem, I will not add this code.

Thanks,
Vitaly

> Thanks,
> Mark.
>
> > To support HOTPLUG_CPU w/o PSCI we need platform implementation of
> > the cpu_die(), which is added by this patch.
> >
> >   arch/arm/mach-keystone/keystone.h |  1 +
> >   arch/arm/mach-keystone/platsmp.c  | 24 ++++++++++++++++++++++++
> >   2 files changed, 25 insertions(+)
> >
> > diff --git a/arch/arm/mach-keystone/keystone.h b/arch/arm/mach-keystone/keystone.h
> > index cd04a1c..93549cf 100644
> > --- a/arch/arm/mach-keystone/keystone.h
> > +++ b/arch/arm/mach-keystone/keystone.h
> > @@ -12,6 +12,7 @@
> >   #define __KEYSTONE_H__
> >
> >   #define KEYSTONE_MON_CPU_UP_IDX		0x00
> > +#define KEYSTONE_MON_CPU_DIE_IDX	0x84000002
> >
> >   #ifndef __ASSEMBLER__
> >
> > diff --git a/arch/arm/mach-keystone/platsmp.c b/arch/arm/mach-keystone/platsmp.c
> > index 5f46a7c..4e5bdde 100644
> > --- a/arch/arm/mach-keystone/platsmp.c
> > +++ b/arch/arm/mach-keystone/platsmp.c
> > @@ -51,7 +51,31 @@ static inline void __cpuinit keystone_smp_secondary_initmem(unsigned int cpu)
> >   {}
> >   #endif
> >
> > +
> > +#ifdef CONFIG_HOTPLUG_CPU
> > +static void keystone_cpu_die(unsigned int cpu)
> > +{
> > +	int error;
> > +
> > +	pr_debug("keystone-smp: cpu_die %d\n", cpu);
> > +
> > +	error = keystone_cpu_smc(KEYSTONE_MON_CPU_DIE_IDX, cpu, 0);
> > +	if (error)
> > +		pr_err("CPU %d die failed with %d\n", cpu, error);
> > +
> > +	/*
> > +	 * we shouldn't come here. But in case something went
> > +	 * wrong the code below prevents kernel from crush
> > +	 */
> > +	while (1)
> > +		cpu_do_idle();
> > +}
> > +#endif
> > +
> >   struct smp_operations keystone_smp_ops __initdata = {
> >   	.smp_boot_secondary	= keystone_smp_boot_secondary,
> >   	.smp_secondary_init     = keystone_smp_secondary_initmem,
> > +#ifdef CONFIG_HOTPLUG_CPU
> > +	.cpu_die		= keystone_cpu_die,
> > +#endif
> >   };
> > --
> > 1.9.1
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