oprofile and ARM A9 hardware counter

[Will Deacon]

On Tue, Apr 03, 2012 at 10:42:30AM +0100, Shilimkar, Santosh wrote:
> On Tue, Apr 3, 2012 at 2:55 PM, Will Deacon <will.deacon at arm.com> wrote:
> > Did you ever get to the bottom of this? This change really is required in
> > order to generate PMU interrupts with the CTI and I don't know of any
> > alternative to the above.
> >
> > Any suggestions?
> >
> Sorry I lost track of this one. There is one relevant patch in Kevin's queue
> for 3.4/fixes. [1] which I generated for perf time stamp issue.

Thanks, I'll take a look.

> Can you try that patch and see if it helps the CTI issue as well ? There
> is an outside chance that it might help. If it doesn't, we should commit
> Ming Lei  patch.

It seems that they're both needed to get reliable PMU operation. Without the
CLKDM_CAN_SWSUP fix, no interrupts are generated at all. Without the patch
below ([1]), it seems that we don't generate enough. So it looks like we
need them both.

> [1] http://lists.infradead.org/pipermail/linux-arm-kernel/2012-March/089679.html

Cheers,

Will