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Message-ID: <53EB48A0.3040204@arm.com>
Date: Wed, 13 Aug 2014 12:14:40 +0100
From: Juri Lelli <juri.lelli@....com>
To: Russell King - ARM Linux <linux@....linux.org.uk>
CC: Lorenzo Pieralisi <Lorenzo.Pieralisi@....com>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
Daniel Lezcano <daniel.lezcano@...aro.org>,
"Rafael J. Wysocki" <rjw@...ysocki.net>,
"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
"linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>,
Juri Lelli <juri.lelli@...il.com>
Subject: Re: [PATCH] cpuidle/cpuidle-big_little: fix reading cpu id part number
On 13/08/14 11:44, Russell King - ARM Linux wrote:
> On Wed, Aug 13, 2014 at 11:04:13AM +0100, Juri Lelli wrote:
>> Thanks a lot for the comment. Does what below address it?
>
> Yes, thanks, but a few of nitpicks though.
>
>> +/*
>> + * smp_cpuid_part() - return part id for a given cpu
>> + *
>> + * @cpu: logical cpu id
>> + *
>> + * Return: part id of logical cpu passed as argument
>> + *
>> + */
>
> If this is supposed to be a kerneldoc-compatible comment, please read
> Documentation/kernel-doc-nano-HOWTO.txt for the correct format.
>
>> +static inline unsigned int smp_cpuid_part(int cpu)
>> +{
>> + struct cpuinfo_arm *cpu_info = &per_cpu(cpu_data, cpu);
>> +
>> + return is_smp() ? (cpu_info->cpuid & ARM_CPU_PART_MASK) :
>
> Parens are not required, and there's a double space before &.
>
> The BNF for the ?: operator is:
>
> cond-expr:
> log-or-expr ? expr : cond-expr
>
> So the compiler knows that whatever is between the ? and : is a single
> expression, and the parens are surplus.
>
>> -static int __init bl_idle_driver_init(struct cpuidle_driver *drv, int cpu_id)
>> +static int __init bl_idle_driver_init(struct cpuidle_driver *drv, int match_id)
>
> If we're changing the name, "part_id" would probably be better than the
> opaque "match_id" here.
>
Right, thanks! What follows has those fixed. Should I send it as a new post?
Thanks,
- Juri
>From 61b88de0f021213f894e843c8e4673203f953ca9 Mon Sep 17 00:00:00 2001
From: Juri Lelli <juri.lelli@....com>
Date: Thu, 7 Aug 2014 17:26:54 +0100
Subject: [PATCH] cpuidle/cpuidle-big_little: fix reading cpu id part number
Commit af040ffc9ba1e079ee4c0748aff64fa3d4716fa5 by Russell King changed
ARM_CPU_PART_X masks, and the way they are returned and checked against.
Usage of read_cpuid_part_number() is now deprecated, and calling places
updated accordingly. This actually broke cpuidle-big_little initialization,
as bl_idle_driver_init() performs a check using and hardcoded mask on
cpu_id.
Create an interface to perform the check (that is now even easier to read).
Define also a proper mask (ARM_CPU_PART_MASK) that makes this kind of checks
cleaner and helps preventing bugs in the future. Update usage accordingly.
Signed-off-by: Juri Lelli <juri.lelli@....com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@....com>
---
arch/arm/include/asm/cputype.h | 3 ++-
arch/arm/include/asm/smp_plat.h | 15 +++++++++++++++
drivers/cpuidle/cpuidle-big_little.c | 13 +++----------
3 files changed, 20 insertions(+), 11 deletions(-)
diff --git a/arch/arm/include/asm/cputype.h b/arch/arm/include/asm/cputype.h
index 963a251..819777d 100644
--- a/arch/arm/include/asm/cputype.h
+++ b/arch/arm/include/asm/cputype.h
@@ -74,6 +74,7 @@
#define ARM_CPU_PART_CORTEX_A12 0x4100c0d0
#define ARM_CPU_PART_CORTEX_A17 0x4100c0e0
#define ARM_CPU_PART_CORTEX_A15 0x4100c0f0
+#define ARM_CPU_PART_MASK 0xff00fff0
#define ARM_CPU_XSCALE_ARCH_MASK 0xe000
#define ARM_CPU_XSCALE_ARCH_V1 0x2000
@@ -179,7 +180,7 @@ static inline unsigned int __attribute_const__ read_cpuid_implementor(void)
*/
static inline unsigned int __attribute_const__ read_cpuid_part(void)
{
- return read_cpuid_id() & 0xff00fff0;
+ return read_cpuid_id() & ARM_CPU_PART_MASK;
}
static inline unsigned int __attribute_const__ __deprecated read_cpuid_part_number(void)
diff --git a/arch/arm/include/asm/smp_plat.h b/arch/arm/include/asm/smp_plat.h
index a252c0b..0ad7d49 100644
--- a/arch/arm/include/asm/smp_plat.h
+++ b/arch/arm/include/asm/smp_plat.h
@@ -8,6 +8,7 @@
#include <linux/cpumask.h>
#include <linux/err.h>
+#include <asm/cpu.h>
#include <asm/cputype.h>
/*
@@ -25,6 +26,20 @@ static inline bool is_smp(void)
#endif
}
+/**
+ * smp_cpuid_part() - return part id for a given cpu
+ * @cpu: logical cpu id.
+ *
+ * Return: part id of logical cpu passed as argument.
+ */
+static inline unsigned int smp_cpuid_part(int cpu)
+{
+ struct cpuinfo_arm *cpu_info = &per_cpu(cpu_data, cpu);
+
+ return is_smp() ? cpu_info->cpuid & ARM_CPU_PART_MASK :
+ read_cpuid_part();
+}
+
/* all SMP configurations have the extended CPUID registers */
#ifndef CONFIG_MMU
#define tlb_ops_need_broadcast() 0
diff --git a/drivers/cpuidle/cpuidle-big_little.c b/drivers/cpuidle/cpuidle-big_little.c
index 344d79fa..ef94c3b 100644
--- a/drivers/cpuidle/cpuidle-big_little.c
+++ b/drivers/cpuidle/cpuidle-big_little.c
@@ -138,25 +138,18 @@ static int bl_enter_powerdown(struct cpuidle_device *dev,
return idx;
}
-static int __init bl_idle_driver_init(struct cpuidle_driver *drv, int cpu_id)
+static int __init bl_idle_driver_init(struct cpuidle_driver *drv, int part_id)
{
- struct cpuinfo_arm *cpu_info;
struct cpumask *cpumask;
- unsigned long cpuid;
int cpu;
cpumask = kzalloc(cpumask_size(), GFP_KERNEL);
if (!cpumask)
return -ENOMEM;
- for_each_possible_cpu(cpu) {
- cpu_info = &per_cpu(cpu_data, cpu);
- cpuid = is_smp() ? cpu_info->cpuid : read_cpuid_id();
-
- /* read cpu id part number */
- if ((cpuid & 0xFFF0) == cpu_id)
+ for_each_possible_cpu(cpu)
+ if (smp_cpuid_part(cpu) == part_id)
cpumask_set_cpu(cpu, cpumask);
- }
drv->cpumask = cpumask;
--
2.0.4
--
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