Re: [PATCH linux-next tag: next-20210322] ARM: aspeed: Add CPU hotplug callbacks for kexec support

[Bruce Mitchell]

On 3/22/2021 09:40, Bruce Mitchell wrote:
> On 3/22/2021 08:57, Bruce Mitchell wrote:
> > These callbacks are required for kexec to function. The AST2600 does not
> > expose any controls for powering down it's CPU cores, so we borrow the
> > approach taken from socfpga and wait in the idle loop.
> >
> > Author: Joel Stanley <joel@xxxxxxxxx>
> >
> > Signed-off-by: Bruce Mitchell <bruce.mitchell@xxxxxxxxxxxxxxxxxx>
> > ---
> >   arch/arm/mach-aspeed/platsmp.c | 20 ++++++++++++++++++++
> >   1 file changed, 20 insertions(+)
> >
> > diff --git a/arch/arm/mach-aspeed/platsmp.c 
> > b/arch/arm/mach-aspeed/platsmp.c
> > index 2324becf7991..1ae3ff5a9701 100644
> > --- a/arch/arm/mach-aspeed/platsmp.c
> > +++ b/arch/arm/mach-aspeed/platsmp.c
> > @@ -7,6 +7,8 @@
> >   #include <linux/of.h>
> >   #include <linux/smp.h>
> >
> > +#include <asm/proc-fns.h>
> > +
> >   #define BOOT_ADDR    0x00
> >   #define BOOT_SIG    0x04
> >
> > @@ -53,9 +55,27 @@ static void __init 
> > aspeed_g6_smp_prepare_cpus(unsigned int max_cpus)
> >       iounmap(base);
> >   }
> >
> > +#ifdef CONFIG_HOTPLUG_CPU
> > +static void aspeed_g6_cpu_die(unsigned int cpu)
> > +{
> > +        /* Do WFI. If we wake up early, go back into WFI */
> > +        while (1)
> > +                cpu_do_idle();
> > +}
> > +
> > +static int aspeed_g6_cpu_kill(unsigned int cpu)
> > +{
> > +        return 1;
> > +}
> > +#endif
> > +
> >   static const struct smp_operations aspeed_smp_ops __initconst = {
> >       .smp_prepare_cpus    = aspeed_g6_smp_prepare_cpus,
> >       .smp_boot_secondary    = aspeed_g6_boot_secondary,
> > +#ifdef CONFIG_HOTPLUG_CPU
> > +    .cpu_die        = aspeed_g6_cpu_die,
> > +    .cpu_kill        = aspeed_g6_cpu_kill,
> > +#endif
> >   };
> >
> >   CPU_METHOD_OF_DECLARE(aspeed_smp, "aspeed,ast2600-smp", 
> > &aspeed_smp_ops);
>
> Adding Andrew Jeffery and Eddie James to the CC list.

Adding linux-kernel@xxxxxxxxxxxxxxx and 
linux-arm-kernel@xxxxxxxxxxxxxxxxxxx based feedback.