From bb21ef19a3d8f586a99310116d40622fb5b79942 Mon Sep 17 00:00:00 2001 From: Robin Murphy Date: Mon, 5 Dec 2022 19:46:13 +0000 Subject: [PATCH] perf/arm-cmn: Reset DTM_PMU_CONFIG at probe 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 Link: https://lore.kernel.org/r/ba5f38b3dc733cd06bfb5e659b697e76d18c2183.1670269572.git.robin.murphy@arm.com Signed-off-by: Will Deacon --- drivers/perf/arm-cmn.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/perf/arm-cmn.c b/drivers/perf/arm-cmn.c index b80a9b7..e220714 100644 --- a/drivers/perf/arm-cmn.c +++ b/drivers/perf/arm-cmn.c @@ -1865,6 +1865,7 @@ 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)); -- 2.7.4