linux-kernel - Re: [PATCH 04/19] ARM64 / ACPI: Introduce arch_fix_phys_package

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Message-ID: <53D69BB3.8040106@arm.com>
Date:	Mon, 28 Jul 2014 19:51:31 +0100
From:	Sudeep Holla <sudeep.holla@....com>
To:	Hanjun Guo <hanjun.guo@...aro.org>,
	Catalin Marinas <Catalin.Marinas@....com>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Mark Rutland <Mark.Rutland@....com>
CC:	Sudeep Holla <sudeep.holla@....com>,
	"graeme.gregory@...aro.org" <graeme.gregory@...aro.org>,
	Arnd Bergmann <arnd@...db.de>,
	"grant.likely@...aro.org" <grant.likely@...aro.org>,
	Will Deacon <Will.Deacon@....com>,
	Jason Cooper <jason@...edaemon.net>,
	Marc Zyngier <Marc.Zyngier@....com>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Daniel Lezcano <daniel.lezcano@...aro.org>,
	Mark Brown <broonie@...aro.org>,
	Robert Richter <rric@...nel.org>,
	Lv Zheng <lv.zheng@...el.com>,
	Robert Moore <robert.moore@...el.com>,
	Lorenzo Pieralisi <Lorenzo.Pieralisi@....com>,
	Liviu Dudau <Liviu.Dudau@....com>,
	Randy Dunlap <rdunlap@...radead.org>,
	Charles Garcia-Tobin <Charles.Garcia-Tobin@....com>,
	"linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 04/19] ARM64 / ACPI: Introduce arch_fix_phys_package_id()
 for cpu topology



On 24/07/14 14:00, Hanjun Guo wrote:
> arch_fix_phys_package_id() will be called in ACPI core to use
> the slot number provided by ACPI to update the physical package
> id, then we can get the right value in the "physical id" field
> of /proc/cpuinfo.
>
> Signed-off-by: Hanjun Guo <hanjun.guo@...aro.org>
> ---
>   arch/arm64/include/asm/topology.h |    2 ++
>   arch/arm64/kernel/topology.c      |   14 ++++++++++++++
>   2 files changed, 16 insertions(+)
>
> diff --git a/arch/arm64/include/asm/topology.h b/arch/arm64/include/asm/topology.h
> index 7ebcd31..2b216d4 100644
> --- a/arch/arm64/include/asm/topology.h
> +++ b/arch/arm64/include/asm/topology.h
> @@ -23,11 +23,13 @@ extern struct cpu_topology cpu_topology[NR_CPUS];
>   void init_cpu_topology(void);
>   void store_cpu_topology(unsigned int cpuid);
>   const struct cpumask *cpu_coregroup_mask(int cpu);
> +void arch_fix_phys_package_id(int num, u32 slot);
>
>   #else
>
>   static inline void init_cpu_topology(void) { }
>   static inline void store_cpu_topology(unsigned int cpuid) { }
> +static inline void arch_fix_phys_package_id(int num, u32 slot) { }
>
>   #endif
>
> diff --git a/arch/arm64/kernel/topology.c b/arch/arm64/kernel/topology.c
> index 43514f9..c547885 100644
> --- a/arch/arm64/kernel/topology.c
> +++ b/arch/arm64/kernel/topology.c
> @@ -281,3 +281,17 @@ void __init init_cpu_topology(void)
>   	if (parse_dt_topology())
>   		reset_cpu_topology();
>   }
> +
> +/*
> + * Use the CPU slot number provided by ACPI to update the physical
> + * package id when cpuid_topo->cluster_id is not available, then we
> + * can get the right value in the "physical id" field of /proc/cpuinfo.
> + */

We don't have "physical id" field in /proc/cpuinfo on ARM64.

> +void arch_fix_phys_package_id(int num, u32 slot)
> +{
> +	struct cpu_topology *cpuid_topo = &cpu_topology[num];
> +
> +	if (cpuid_topo->cluster_id == -1)
> +		cpuid_topo->cluster_id = slot;
> +}
> +EXPORT_SYMBOL_GPL(arch_fix_phys_package_id);
>

The ACPI core uses this function to set the package id as read from
_SUN from the device. As per spec, _SUN is used by OSPM UI to identify
slots for the user. Do we know how will this be used on ARM64 ?

If not clear at this time, better to define it or keep it empty. I see
even x86 does nothing in that function.

Regards,
Sudeep

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