Lorenzo Pieralisi <lorenzo.pieral...@arm.com> wrote @ Thu, 10 Jan 2013 15:33:34
+0100:
> On Thu, Jan 10, 2013 at 02:03:50PM +0000, Hiroshi Doyu wrote:
> > Lorenzo Pieralisi <lorenzo.pieral...@arm.com> wrote @ Thu, 10 Jan 2013
> > 14:47:23 +0100:
>
> [...]
>
> > > > +static int __init smp_detect_ncores(void)
> > > > +{
> > > > + unsigned int ncores, mpidr;
> > > > + u32 l2ctlr;
> > > > + phys_addr_t pa;
> > > > +
> > > > + mpidr = read_cpuid_mpidr();
> > > > + switch (mpidr) {
> > > > + case ARM_CPU_PART_CORTEX_A15:
> > > > + asm("mrc p15, 1, %0, c9, c0, 2\n" : "=r" (l2ctlr));
> > > > + ncores = ((l2ctlr >> 24) & 3) + 1;
> > > > + break;
> > >
> > > I do not want to see the case above merged. We keep the existing legacy
> > > methods there for legacy reasons and as a fall-back mechanism but I am not
> > > keen on adding new HW probing code to detect the number of cores.
> > >
> > > From A15/A7 onwards DT-only cpu map initialization is the way to go.
> >
> > Ok, then, smp_detect_ncores(void) could be...
> >
> > static int __init smp_detect_ncores(void)
> > {
> > unsigned int ncores, mpidr;
> > phys_addr_t pa;
> >
> > mpidr = read_cpuid_mpidr();
>
> Careful, MPIDR is not at all what you want. MIDR is.
>
> > switch (mpidr) {
> > case ARM_CPU_PART_CORTEX_A9:
> > /* Get SCU physical base */
> > asm("mrc p15, 4, %0, c15, c0, 0" : "=r" (pa));
> > scu_base = IO_ADDRESS(pa);
> > ncores = scu_get_core_count(scu_base);
> > break;
> > case ARM_CPU_PART_CORTEX_A15:
>
> Remove the ARM_CPU_PART_CORTEX_A15 case, I do not see how it helps.
>
> And be careful with the case matching, if I am not mistaken read_cpuid_id()
> (which is the function you have to use) will return the full MIDR, you need
> to mask the return value.
Oops, I'll fix.
> > default:
> > pr_warn("Unsupported MPIDR %x\n", mpidr);
> > ncores = 1;
> > break;
>
> This is reasonable.
Ok, thank you for your reivew, I'll keep this func,
"smp_detect_ncores()" in this file since it's mostly for the backward
compatibility. Not necessary to be relocated in common place newly..
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