On Fri, 10 Jan 2014, Will Deacon wrote:
> In the absence of a core change, I think I'd rather have something like your
> second patch, but without the extra no_overflow_irq field (you can check the
> platform device, as I mentioned previously).
Something like the following? It works on my rasp-pi, still waiting for
the compile to finish on the pandaboard so I haven't verified that the
has-working-interrupt case still works.
---
Allow hardware perf_events to be enabled even if no overflow
interrupt is available. Return EOPNOTSUPP if a sampling event
is attempted and the interrupt is not available.
This is necessary for access to hardware perf_events on
the Raspberry-Pi (bcm2835).
Signed-off-by: Vince Weaver <vincent.wea...@maine.edu>
diff --git a/arch/arm/kernel/perf_event.c b/arch/arm/kernel/perf_event.c
index bc3f2ef..e2c4aa2 100644
--- a/arch/arm/kernel/perf_event.c
+++ b/arch/arm/kernel/perf_event.c
@@ -397,7 +397,7 @@ __hw_perf_event_init(struct perf_event *event)
*/
hwc->config_base |= (unsigned long)mapping;
- if (!hwc->sample_period) {
+ if (!is_sampling_event(event)) {
/*
* For non-sampling runs, limit the sample_period to half
* of the counter width. That way, the new counter value
@@ -407,6 +407,14 @@ __hw_perf_event_init(struct perf_event *event)
hwc->sample_period = armpmu->max_period >> 1;
hwc->last_period = hwc->sample_period;
local64_set(&hwc->period_left, hwc->sample_period);
+ } else {
+
+ /*
+ * If we have no PMU interrupt we cannot sample.
+ */
+ if (platform_get_irq(armpmu->plat_device, 0) < 0)
+ return -EOPNOTSUPP;
+
}
if (event->group_leader != event) {
diff --git a/arch/arm/kernel/perf_event_cpu.c b/arch/arm/kernel/perf_event_cpu.c
index d85055c..7a84738 100644
--- a/arch/arm/kernel/perf_event_cpu.c
+++ b/arch/arm/kernel/perf_event_cpu.c
@@ -97,8 +97,8 @@ static int cpu_pmu_request_irq(struct arm_pmu *cpu_pmu,
irq_handler_t handler)
irqs = min(pmu_device->num_resources, num_possible_cpus());
if (irqs < 1) {
- pr_err("no irqs for PMUs defined\n");
- return -ENODEV;
+ printk_once("no irqs for PMUs defined, sampled events not
supported\n");
+ return 0;
}
for (i = 0; i < irqs; ++i) {
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
