[PATCH 1/2] ARM: perf: reset counters on all CPUs during initialisation

Will Deacon will.deacon at arm.com
Wed Mar 16 12:21:09 EDT 2011

Hi Jean,

> On Wed, Mar 16, 2011 at 4:38 PM, Will Deacon <will.deacon at arm.com> wrote:
> > ARMv7 dictates that the interrupt-enable and count-enable registers for
> > each PMU counter are UNKNOWN following core reset.
> Great! Is this development driven by actual issues or by precaution?

Just precautionary, but it's also a precursor to some power management
work in ARM which might leave the registers in a funny state when they
come out of a low-power state. This code at least gives them an entry
hook for dealing with that.
> >
> > This patch adds an arch_initcall to the ARMv7 perf events backend which
> > disables the counters on each CPU prior to setting the Enable bit in the
> > PMCR.
> Also the function rename is a good thing.


> >
> > Cc: Jean Pihet <jean.pihet at newoldbits.com>
> > Signed-off-by: Will Deacon <will.deacon at arm.com>
> Acked-by: Jean Pihet <j-pihet at ti.com>

Thanks for the Ack,


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