[PATCH V5 2/3] coresight: etm: Make cycle count threshold user configurable
From: Anshuman Khandual <hidden>
Date: 2023-08-21 04:52:45
Also in:
linux-doc, lkml
Subsystem:
arm/coresight framework and drivers, hardware tracing facilities, the rest · Maintainers:
Suzuki K Poulose, Alexander Shishkin, Linus Torvalds
Cycle counting is enabled, when requested and supported but with a default threshold value ETM_CYC_THRESHOLD_DEFAULT i.e 0x100 getting into TRCCCCTLR, representing the minimum interval between cycle count trace packets. This makes cycle threshold user configurable, from the user space via perf event attributes. Although it falls back using ETM_CYC_THRESHOLD_DEFAULT, in case no explicit request. As expected it creates a sysfs file as well. /sys/bus/event_source/devices/cs_etm/format/cc_threshold New 'cc_threshold' uses 'event->attr.config3' as no more space is available in 'event->attr.config1' or 'event->attr.config2'. Cc: Suzuki K Poulose <suzuki.poulose@arm.com> Cc: Mike Leach <redacted> Cc: James Clark <redacted> Cc: Leo Yan <redacted> Cc: coresight@lists.linaro.org Cc: linux-arm-kernel@lists.infradead.org Cc: linux-doc@vger.kernel.org Cc: linux-kernel@vger.kernel.org Reviewed-by: Mike Leach <redacted> Signed-off-by: Anshuman Khandual <redacted> --- drivers/hwtracing/coresight/coresight-etm-perf.c | 2 ++ drivers/hwtracing/coresight/coresight-etm4x-core.c | 9 +++++++-- 2 files changed, 9 insertions(+), 2 deletions(-)
diff --git a/drivers/hwtracing/coresight/coresight-etm-perf.c b/drivers/hwtracing/coresight/coresight-etm-perf.c
index 5ca6278baff4..09f75dffae60 100644
--- a/drivers/hwtracing/coresight/coresight-etm-perf.c
+++ b/drivers/hwtracing/coresight/coresight-etm-perf.c@@ -68,6 +68,7 @@ PMU_FORMAT_ATTR(preset, "config:0-3"); PMU_FORMAT_ATTR(sinkid, "config2:0-31"); /* config ID - set if a system configuration is selected */ PMU_FORMAT_ATTR(configid, "config2:32-63"); +PMU_FORMAT_ATTR(cc_threshold, "config3:0-11"); /*
@@ -101,6 +102,7 @@ static struct attribute *etm_config_formats_attr[] = { &format_attr_preset.attr, &format_attr_configid.attr, &format_attr_branch_broadcast.attr, + &format_attr_cc_threshold.attr, NULL, };
diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c
index 1308d89f58d1..9edba406f523 100644
--- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
+++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c@@ -635,7 +635,7 @@ static int etm4_parse_event_config(struct coresight_device *csdev, struct etmv4_config *config = &drvdata->config; struct perf_event_attr *attr = &event->attr; unsigned long cfg_hash; - int preset; + int preset, cc_threshold; /* Clear configuration from previous run */ memset(config, 0, sizeof(struct etmv4_config));
@@ -658,7 +658,12 @@ static int etm4_parse_event_config(struct coresight_device *csdev, if (attr->config & BIT(ETM_OPT_CYCACC)) { config->cfg |= TRCCONFIGR_CCI; /* TRM: Must program this for cycacc to work */ - config->ccctlr = ETM_CYC_THRESHOLD_DEFAULT; + cc_threshold = attr->config3 & ETM_CYC_THRESHOLD_MASK; + if (!cc_threshold) + cc_threshold = ETM_CYC_THRESHOLD_DEFAULT; + if (cc_threshold < drvdata->ccitmin) + cc_threshold = drvdata->ccitmin; + config->ccctlr = cc_threshold; } if (attr->config & BIT(ETM_OPT_TS)) { /*
--
2.25.1
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