[PATCH] cpuidle/cpuidle-big_little: fix reading cpu id part number

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:

quoted

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.

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 ?

Thanks,
Lorenzo