Hi all,
On 08/08/14 17:47, Lorenzo Pieralisi wrote:
> On Fri, Aug 08, 2014 at 02:21:05PM +0100, Russell King - ARM Linux wrote:
>> On Fri, Aug 08, 2014 at 01:42:37PM +0100, Juri Lelli wrote:
>>> Commit af040ffc9ba1 ("ARM: make it easier to check the CPU part number
>>> correctly") 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.
>>>
>>> Update the check to reflect changes on ARM_CPU_PART_X masks. Also,
>>> make the check easier to understand.
>>
>> I don't like this "let's work out our own way to check the CPU type"
>> stuff which people seem to create. Let's try and do the job better
>> and have some proper interfaces to do this kind of thing.
>>
>> Maybe we should have smp_cpuid_part(cpu) which returns the CPU vendor/
>> part identifier for the particular CPU in an efficient manner.
Thanks a lot for the comment. Does what below address it?
>
> Ok, basically an inline function that either read and mask the cpuid
> stashed at boot in cpu_data or read the part number straight away on UP.
>
> Should it belong in asm/smp_plat.h ?
>
Ok, this is how it could look like.
>From 6dbaf6c2eb34b06966daf5e90d1f08a0202c86e2 Mon Sep 17 00:00:00 2001
From: Juri Lelli <[email protected]>
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 <[email protected]>
Signed-off-by: Lorenzo Pieralisi <[email protected]>
---
arch/arm/include/asm/cputype.h | 3 ++-
arch/arm/include/asm/smp_plat.h | 17 +++++++++++++++++
drivers/cpuidle/cpuidle-big_little.c | 13 +++----------
3 files changed, 22 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..b84ee77 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 +26,22 @@ 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..1703d32 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 match_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) == match_id)
cpumask_set_cpu(cpu, cpumask);
- }
drv->cpumask = cpumask;
--
2.0.4
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