Subject: [PATCH 06/11] arm: arm64: Add routine to determine cpuid of other cpus

From: [email-masked] (Jeremy Linton)
Date: Wed, 6 Jul 2016 19:34:23 -0500

On 07/06/2016 11:30 AM, Will Deacon wrote:
> On Tue, Jun 21, 2016 at 12:11:44PM -0500, Jeremy Linton wrote:
>> It is helpful if we can read the cpuid/midr of other CPUs
>> in the system independent of arm/arm64.
>>
>> Signed-off-by: Jeremy Linton <[email-masked]>
>> ---
>>   arch/arm/include/asm/cputype.h   | 6 +++++-
>>   arch/arm64/include/asm/cputype.h | 4 ++++
>>   2 files changed, 9 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/arm/include/asm/cputype.h b/arch/arm/include/asm/cputype.h
>> index 1ee94c7..e391b67 100644
>> --- a/arch/arm/include/asm/cputype.h
>> +++ b/arch/arm/include/asm/cputype.h
>> @@ -81,6 +81,8 @@
>>   #define ARM_CPU_XSCALE_ARCH_V2		0x4000
>>   #define ARM_CPU_XSCALE_ARCH_V3		0x6000
>>
>> +#define ARM_PARTNUM(cpuid_id) (cpuid_id & ARM_CPU_PART_MASK)
>> +
>>   extern unsigned int processor_id;
>>
>>   #ifdef CONFIG_CPU_CP15
>> @@ -180,7 +182,7 @@ static inline unsigned int __attribute_const__ read_cpuid_implementor(void)
>>    */
>>   static inline unsigned int __attribute_const__ read_cpuid_part(void)
>>   {
>> -	return read_cpuid_id() & ARM_CPU_PART_MASK;
>> +	return ARM_PARTNUM(read_cpuid_id());
>
> I don't understand why you need to make this change.

The short answer is that the ARM_PARTNUM stuff is left over from v4 (?) 
of the patch, where it seemed a good idea to create a macro that was 
arm/arm64 independent for use in arm_pmu.c. Somewhere along there I 
reverted the ARM_PARTNUM to MIDR_PARTNUM in the arm_pmu_acpi.c but 
didn't drop that portion from this patch. Partially because it seems 
like a good idea. OTOH, your right probably doesn't belong here without 
the large cleanup which would form their own patch set.