Re: [PATCH 1/2] perf: dsu: Allow multiple devices share same IRQ.

[Mark Rutland <mark.rutland@arm.com>]

On Thu, Mar 19, 2020 at 02:32:51PM +0000, Mark Rutland wrote:
> On Tue, Mar 17, 2020 at 05:26:15PM -0700, Tuan Phan wrote:
> > Add IRQF_SHARED flag when register IRQ such that multiple dsu
> > devices can share same IRQ.
> > 
> > Signed-off-by: Tuan Phan <tuanphan@os.amperecomputing.com>
> 
> I don't think that this makes sense; further I think that this
> highlights that the current driver doesn't support such a configuration
> for other reasons.
> 
> A DSU instance can only be accessed from a CPU associated with it, since
> it's accessed via sysregs. The IRQ handler must run on one of those
> CPUs.
> 
> To handle that, the DSU PMU driver will need to gain an understanding of
> which CPUs are associated with the instance. As it stands the driver
> seems to assume that there's a single DSU instance, and that all CPUs
> are affine to that same instance.

Sorry, I misread dsu_pmu_get_online_cpu_any_but(), multiple instances
are handled already.

> So NAK to this patch, given the above.

Regardless, this NAK stands.

Thanks,
Mark.