linux-kernel - Re: [PATCH v8 1/2] arm: introduce psci_smp

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Message-ID: <20130425084711.GA12848@mudshark.cambridge.arm.com>
Date:	Thu, 25 Apr 2013 09:47:11 +0100
From:	Will Deacon <will.deacon@....com>
To:	Stefano Stabellini <stefano.stabellini@...citrix.com>
Cc:	"xen-devel@...ts.xensource.com" <xen-devel@...ts.xensource.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"arnd@...db.de" <arnd@...db.de>,
	"nicolas.pitre@...aro.org" <nicolas.pitre@...aro.org>,
	"rob.herring@...xeda.com" <rob.herring@...xeda.com>,
	"linux@....linux.org.uk" <linux@....linux.org.uk>,
	"olof@...om.net" <olof@...om.net>
Subject: Re: [PATCH v8 1/2] arm: introduce psci_smp_ops

Hi Stefano,

On Wed, Apr 24, 2013 at 07:40:18PM +0100, Stefano Stabellini wrote:
> Rename virt_smp_ops to psci_smp_ops and move them to arch/arm/kernel/psci_smp.c.
> Remove mach-virt/platsmp.c, now unused.
> Compile psci_smp if CONFIG_ARM_PSCI and CONFIG_SMP.
> 
> Add a cpu_die smp_op based on psci_ops.cpu_off.
> 
> Initialize PSCI before setting smp_ops in setup_arch.
> Use psci_smp_ops if the platform doesn't provide its own smp_ops.
> 
> If PSCI is available on the platform, prefer psci_smp_ops over the
> platform smp_ops.
> 
> Changes in v8:
> - merge "prefer psci_smp_ops over mdesc->smp" into this patch.
> 
> Changes in v6:
> - fixed return values for psci_smp_available and psci_init ifndef
> CONFIG_ARM_PSCI.
> 
> Changes in v5:
> - document psci_operations;
> - psci_init returns NULL.
> 
> Signed-off-by: Stefano Stabellini <stefano.stabellini@...citrix.com>
> ---
>  arch/arm/include/asm/psci.h  |   29 ++++++++++++++++++
>  arch/arm/kernel/Makefile     |    5 ++-
>  arch/arm/kernel/psci.c       |    7 ++--
>  arch/arm/kernel/psci_smp.c   |   67 ++++++++++++++++++++++++++++++++++++++++++
>  arch/arm/kernel/setup.c      |    7 ++++-
>  arch/arm/mach-virt/Makefile  |    1 -
>  arch/arm/mach-virt/platsmp.c |   58 ------------------------------------
>  arch/arm/mach-virt/virt.c    |    3 --
>  8 files changed, 109 insertions(+), 68 deletions(-)
>  create mode 100644 arch/arm/kernel/psci_smp.c
>  delete mode 100644 arch/arm/mach-virt/platsmp.c
> 
> diff --git a/arch/arm/include/asm/psci.h b/arch/arm/include/asm/psci.h
> index ce0dbe7..fa44417 100644
> --- a/arch/arm/include/asm/psci.h
> +++ b/arch/arm/include/asm/psci.h
> @@ -23,6 +23,26 @@ struct psci_power_state {
>  	u8	affinity_level;
>  };
>  
> +/*
> + * cpu_suspend   Suspend the execution on a CPU
> + * @state        we don't currently describe affinity levels, so just pass 0.
> + * @entry_point  the first instruction to be executed on return
> + * returns 0  success, < 0 on failure
> + *
> + * cpu_off       Power down a CPU
> + * @state        we don't currently describe affinity levels, so just pass 0.
> + * no return on successful call
> + *
> + * cpu_on        Power up a CPU
> + * @cpuid        cpuid of target CPU, as from MPIDR
> + * @entry_point  the first instruction to be executed on return
> + * returns 0  success, < 0 on failure
> + *
> + * migrate       Migrate the context to a different CPU
> + * @cpuid        cpuid of target CPU, as from MPIDR
> + * returns 0  success, < 0 on failure
> + *
> + */

Can you move these comments into psci-smp.c please? They're really specific
to the implementation there, and if we put them in a header we're lying to
ourselves about the parameters actually described by the PSCI specification.

With that change:

  Acked-by: Will Deacon <will.deacon@....com>

Will
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