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-rw-r--r--arch/metag/kernel/perf/perf_event.c22
1 files changed, 15 insertions, 7 deletions
diff --git a/arch/metag/kernel/perf/perf_event.c b/arch/metag/kernel/perf/perf_event.c
index 8096db2a550b..a00f527eade5 100644
--- a/arch/metag/kernel/perf/perf_event.c
+++ b/arch/metag/kernel/perf/perf_event.c
@@ -643,13 +643,15 @@ static void metag_pmu_enable_counter(struct hw_perf_event *event, int idx)
config = tmp >> 4;
}
- /*
- * Enabled counters start from 0. Early cores clear the count on
- * write but newer cores don't, so we make sure that the count is
- * set to 0.
- */
tmp = ((config & 0xf) << 28) |
((1 << 24) << cpu_2_hwthread_id[get_cpu()]);
+ if (metag_pmu->max_period)
+ /*
+ * Cores supporting overflow interrupts may have had the counter
+ * set to a specific value that needs preserving.
+ */
+ tmp |= metag_in32(PERF_COUNT(idx)) & 0x00ffffff;
+
metag_out32(tmp, PERF_COUNT(idx));
unlock:
raw_spin_unlock_irqrestore(&events->pmu_lock, flags);
@@ -764,10 +766,16 @@ static irqreturn_t metag_pmu_counter_overflow(int irq, void *dev)
/*
* Enable the counter again once core overflow processing has
- * completed.
+ * completed. Note the counter value may have been modified while it was
+ * inactive to set it up ready for the next interrupt.
*/
- if (!perf_event_overflow(event, &sampledata, regs))
+ if (!perf_event_overflow(event, &sampledata, regs)) {
+ __global_lock2(flags);
+ counter = (counter & 0xff000000) |
+ (metag_in32(PERF_COUNT(idx)) & 0x00ffffff);
metag_out32(counter, PERF_COUNT(idx));
+ __global_unlock2(flags);
+ }
return IRQ_HANDLED;
}