[PATCH v2] Added perf functionality to mmdc driver

quoted

	Added cpumask and migration handling support to driver
	Validated event during event_init
	Added code to properly stop counters
	Used perf_invalid_context instead of perf_sw_context
	Added hrtimer to poll for overflow
	Added better description
	Added support for multiple mmdcs

As I commented on v1 w.r.t. the above, I would appreciate being Cc'd on
future versions of this patch.

Sorry about that, I'll be sure to CC you in the future. 

quoted

+static void mmdc_event_start(struct perf_event *event, int flags) {
+	struct mmdc_pmu *pmu_mmdc = to_mmdc_pmu(event->pmu);
+	void __iomem *mmdc_base, *reg;
+
+	local64_set(&event->count, 0);
+	mmdc_base = pmu_mmdc->mmdc_base;
+	reg = mmdc_base + MMDC_MADPCR0;
+	hrtimer_start(&pmu_mmdc->hrtimer, mmdc_timer_period(),
+			HRTIMER_MODE_REL_PINNED);

Why is a hrtimer necessary? Is this just copy-pasted from CCN, or do you
have similar HW issues?

Is there no overflow interrupt?

When overflow occurs, a register bit is set to one. There is no overflow
interrupt which is why the timer is needed. 

Thanks a lot for the feedback!