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Re: [Xen-devel] [ARM:PATCH v1 1/1] Add Odroid-XU (Exynos5410) support

On Tue, 2014-07-29 at 08:49 -0700, Suriyan Ramasami wrote:
> On Tue, Jul 29, 2014 at 12:30 AM, Ian Campbell <Ian.Campbell@xxxxxxxxxx> 
> wrote:
> > On Mon, 2014-07-28 at 15:25 -0700, Suriyan Ramasami wrote:
> >> So, why is any other CPU other than CPU0 not able to read the CNTFRQ
> >> register? Is my CPU turn on code causing this issue, or is something
> >> extra needed to be done to the other CPUs in the bring up code?
> >
> > Are you sure you are writing CNTFRQ on every pCPU? This is a processor
> > local register so it needs setting everywhere, not just once.
> >
> Ah! I didn't know that. I was setting it only once on the booting CPU
> in u-boot through am smc call.

All cp registers are always local. At least I can't think of an
exception offhand.

> > You symptoms are sounding very much like it is only set on the boot CPU.
> >
> Thanks for pointing this out. I am wondering if I should go the psci
> route for the Exynos 5410 or add an smc call in the cpu bring up code.

PSCI would certainly be preferable if it is available for your platform.

A basic PSCI framework got added to u-boot mainline just this week, if
that is helpful.


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