[PATCH 2/2] coresight: etm3x: fix inconsistencies with sysfs configration

[Yeoreum Yun <yeoreum.yun@arm.com>]

The current ETM3x configuration via sysfs can lead to the following
inconsistencies:

- If a configuration is modified via sysfs while a perf session is
  active, the running configuration may differ between before
  a sched-out and after a subsequent sched-in.

To resolve these inconsistencies, the configuration should be separated into:

  - active_config, which represents the currently applied configuration
  - config, which stores the settings configured via sysfs.

Signed-off-by: Yeoreum Yun <yeoreum.yun@arm.com>
---
 drivers/hwtracing/coresight/coresight-etm.h        |  2 ++
 drivers/hwtracing/coresight/coresight-etm3x-core.c | 11 +++++++----
 2 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-etm.h b/drivers/hwtracing/coresight/coresight-etm.h
index 1d753cca2943..d94adb08a235 100644
--- a/drivers/hwtracing/coresight/coresight-etm.h
+++ b/drivers/hwtracing/coresight/coresight-etm.h
@@ -226,6 +226,7 @@ struct etm_config {
  * @etmccr:	value of register ETMCCR.
  * @etmccer:	value of register ETMCCER.
  * @traceid:	value of the current ID for this component.
+ * @active_config:	structure holding current running configuration parameters.
  * @config:	structure holding configuration parameters.
  */
 struct etm_drvdata {
@@ -248,6 +249,7 @@ struct etm_drvdata {
 	u32				etmccr;
 	u32				etmccer;
 	u32				traceid;
+	struct etm_config		active_config;
 	struct etm_config		config;
 };
 
diff --git a/drivers/hwtracing/coresight/coresight-etm3x-core.c b/drivers/hwtracing/coresight/coresight-etm3x-core.c
index a547a6d2e0bd..30390ec38762 100644
--- a/drivers/hwtracing/coresight/coresight-etm3x-core.c
+++ b/drivers/hwtracing/coresight/coresight-etm3x-core.c
@@ -308,7 +308,7 @@ void etm_config_trace_mode(struct etm_config *config)
 static int etm_parse_event_config(struct etm_drvdata *drvdata,
 				  struct perf_event *event)
 {
-	struct etm_config *config = &drvdata->config;
+	struct etm_config *config = &drvdata->active_config;
 	struct perf_event_attr *attr = &event->attr;
 	u8 ts_level;
 
@@ -367,7 +367,7 @@ static int etm_enable_hw(struct etm_drvdata *drvdata)
 {
 	int i, rc;
 	u32 etmcr;
-	struct etm_config *config = &drvdata->config;
+	struct etm_config *config = &drvdata->active_config;
 	struct coresight_device *csdev = drvdata->csdev;
 
 	CS_UNLOCK(drvdata->csa.base);
@@ -513,6 +513,8 @@ static int etm_enable_sysfs(struct coresight_device *csdev, struct coresight_pat
 
 	spin_lock(&drvdata->spinlock);
 
+	drvdata->active_config = drvdata->config;
+
 	drvdata->traceid = path->trace_id;
 
 	/*
@@ -563,7 +565,7 @@ static int etm_enable(struct coresight_device *csdev, struct perf_event *event,
 static void etm_disable_hw(struct etm_drvdata *drvdata)
 {
 	int i;
-	struct etm_config *config = &drvdata->config;
+	struct etm_config *config = &drvdata->active_config;
 	struct coresight_device *csdev = drvdata->csdev;
 
 	CS_UNLOCK(drvdata->csa.base);
@@ -877,7 +879,8 @@ static int etm_probe(struct amba_device *adev, const struct amba_id *id)
 	if (etm_arch_supported(drvdata->arch) == false)
 		return -EINVAL;
 
-	etm_set_default(&drvdata->config);
+	etm_set_default(&drvdata->active_config);
+	drvdata->config = drvdata->active_config;
 
 	pdata = coresight_get_platform_data(dev);
 	if (IS_ERR(pdata))
-- 
LEVI:{C3F47F37-75D8-414A-A8BA-3980EC8A46D7}