Re: [PATCH] drivers/perf: arm-pmu: Handle per-interrupt affinity mask

[Will Deacon]

On Fri, Jul 01, 2016 at 02:21:31PM +0100, Marc Zyngier wrote:
> On a big-little system, PMUs can be wired to CPUs using per CPU
> interrups (PPI). In this case, it is important to make sure that
> the enable/disable do happen on the right set of CPUs.
> 
> So instead of relying on the interrupt-affinity property, we can
> use the actual percpu affinity that DT exposes as part of the
> interrupt specifier. The DT binding is also updated to reflect
> the fact that the interrupt-affinity property shouldn't be used
> in that case.

[...]

> -	/* If we didn't manage to parse anything, claim to support all CPUs */
> -	if (cpumask_weight(&pmu->supported_cpus) == 0)
> -		cpumask_setall(&pmu->supported_cpus);
> +	/* If we didn't manage to parse anything, try the interrupt affinity */
> +	if (cpumask_weight(&pmu->supported_cpus) == 0) {
> +		if (!using_spi) {
> +			/* If using PPIs, check the affinity of the partition */
> +			int irq = platform_get_irq(pdev, 0);
> +			irq_get_percpu_devid_partition(irq,
> +						       &pmu->supported_cpus);

Should we not at least propagate the failure if this returns -EINVAL?

Will