| Message ID | ba5f38b3dc733cd06bfb5e659b697e76d18c2183.1670269572.git.robin.murphy@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | perf/arm-cmn: Reset DTM_PMU_CONFIG at probe | expand |
On Mon, 5 Dec 2022 19:46:13 +0000, Robin Murphy wrote: > Although we treat the DTM counters as free-running such that we're not > too concerned about the initial DTM state, it's possible for a previous > user to have left DTM counters enabled and paired with DTC counters. > Thus if the first events are scheduled using some, but not all, DTMs, > the as-yet-unused ones could end up adding spurious increments to the > event counts at the DTC. Make sure we sync our initial DTM_PMU_CONFIG > state to all the DTMs at probe time to avoid that possibility. > > [...] Applied to will (for-next/perf), thanks! [1/1] perf/arm-cmn: Reset DTM_PMU_CONFIG at probe https://git.kernel.org/will/c/bb21ef19a3d8 Cheers,
diff --git a/drivers/perf/arm-cmn.c b/drivers/perf/arm-cmn.c index 0b2df72cee9f..81b0dfd511aa 100644 --- a/drivers/perf/arm-cmn.c +++ b/drivers/perf/arm-cmn.c @@ -1862,6 +1862,7 @@ static void arm_cmn_init_dtm(struct arm_cmn_dtm *dtm, struct arm_cmn_node *xp, i dtm->base = xp->pmu_base + CMN_DTM_OFFSET(idx); dtm->pmu_config_low = CMN_DTM_PMU_CONFIG_PMU_EN; + writeq_relaxed(dtm->pmu_config_low, dtm->base + CMN_DTM_PMU_CONFIG); for (i = 0; i < 4; i++) { dtm->wp_event[i] = -1; writeq_relaxed(0, dtm->base + CMN_DTM_WPn_MASK(i));
Although we treat the DTM counters as free-running such that we're not too concerned about the initial DTM state, it's possible for a previous user to have left DTM counters enabled and paired with DTC counters. Thus if the first events are scheduled using some, but not all, DTMs, the as-yet-unused ones could end up adding spurious increments to the event counts at the DTC. Make sure we sync our initial DTM_PMU_CONFIG state to all the DTMs at probe time to avoid that possibility. Signed-off-by: Robin Murphy <robin.murphy@arm.com> --- drivers/perf/arm-cmn.c | 1 + 1 file changed, 1 insertion(+)