Re: [PATCH v5 06/14] coresight: etm3x: Update ETM3 driver to use Trace ID API

On 01/11/2022 16:30, Mike Leach wrote:

Use the TraceID API to allocate ETM trace IDs dynamically.

As with the etm4x we allocate on enable / disable for perf, allocate on enable / reset for sysfs.

Additionally we allocate on sysfs file read as both perf and sysfs can read the ID before enabling the hardware.

Remove sysfs option to write trace ID - which is inconsistent with both the dynamic allocation method and the fixed allocation method previously used.

Signed-off-by: Mike Leach mike.leach@linaro.org

drivers/hwtracing/coresight/coresight-etm.h | 2 + .../coresight/coresight-etm3x-core.c | 69 +++++++++++++++++-- .../coresight/coresight-etm3x-sysfs.c | 27 ++------ 3 files changed, 72 insertions(+), 26 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-etm.h b/drivers/hwtracing/coresight/coresight-etm.h index f3ab96eaf44e..3667428d38b6 100644 --- a/drivers/hwtracing/coresight/coresight-etm.h +++ b/drivers/hwtracing/coresight/coresight-etm.h @@ -287,4 +287,6 @@ int etm_get_trace_id(struct etm_drvdata *drvdata); void etm_set_default(struct etm_config *config); void etm_config_trace_mode(struct etm_config *config); struct etm_config *get_etm_config(struct etm_drvdata *drvdata); +int etm_read_alloc_trace_id(struct etm_drvdata *drvdata); +void etm_release_trace_id(struct etm_drvdata *drvdata); #endif diff --git a/drivers/hwtracing/coresight/coresight-etm3x-core.c b/drivers/hwtracing/coresight/coresight-etm3x-core.c index d0ab9933472b..9a7a9e974d41 100644 --- a/drivers/hwtracing/coresight/coresight-etm3x-core.c +++ b/drivers/hwtracing/coresight/coresight-etm3x-core.c @@ -32,6 +32,7 @@ #include "coresight-etm.h" #include "coresight-etm-perf.h" +#include "coresight-trace-id.h" /*

• Not really modular but using module_param is the easiest way to

@@ -490,16 +491,59 @@ static int etm_trace_id(struct coresight_device *csdev) return etm_get_trace_id(drvdata); } +int etm_read_alloc_trace_id(struct etm_drvdata *drvdata) +{

• int trace_id;
• /*

• * This will allocate a trace ID to the cpu,
  

• * or return the one currently allocated.
  

• *
  

• * trace id function has its own lock
  

• */
  

• trace_id = coresight_trace_id_get_cpu_id(drvdata->cpu);
• if (IS_VALID_ID(trace_id))

• drvdata->traceid = (u8)trace_id;
  

• else

• dev_err(&drvdata->csdev->dev,
  

• 	"Failed to allocate trace ID for %s on CPU%d\n",
  

• 	dev_name(&drvdata->csdev->dev), drvdata->cpu);
  

• return trace_id;

+}

+void etm_release_trace_id(struct etm_drvdata *drvdata) +{

• coresight_trace_id_put_cpu_id(drvdata->cpu);

+}

• static int etm_enable_perf(struct coresight_device *csdev, struct perf_event *event) { struct etm_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
• int trace_id;

if (WARN_ON_ONCE(drvdata->cpu != smp_processor_id())) return -EINVAL; /* Configure the tracer based on the session's specifics */ etm_parse_event_config(drvdata, event);

• /*

• * perf allocates cpu ids as part of _setup_aux() - device needs to use
  

• * the allocated ID. This reads the current version without allocation.
  

• *
  

• * This does not use the trace id lock to prevent lock_dep issues
  

• * with perf locks - we know the ID cannot change until perf shuts down
  

• * the session
  

• */
  

• trace_id = coresight_trace_id_read_cpu_id(drvdata->cpu);
• if (!IS_VALID_ID(trace_id)) {

• dev_err(&drvdata->csdev->dev, "Failed to set trace ID for %s on CPU%d\n",
  

• 	dev_name(&drvdata->csdev->dev), drvdata->cpu);
  

• return -EINVAL;
  

• }
• drvdata->traceid = (u8)trace_id;
• /* And enable it */ return etm_enable_hw(drvdata); }

@@ -512,6 +556,11 @@ static int etm_enable_sysfs(struct coresight_device *csdev) spin_lock(&drvdata->spinlock);

• /* sysfs needs to allocate and set a trace ID */
• ret = etm_read_alloc_trace_id(drvdata);
• if (ret < 0)

• goto unlock_enable_sysfs;
  

• /*
  • Configure the ETM only if the CPU is online. If it isn't online
  • hw configuration will take place on the local CPU during bring up.

@@ -528,6 +577,10 @@ static int etm_enable_sysfs(struct coresight_device *csdev) ret = -ENODEV; }

• if (ret)

• etm_release_trace_id(drvdata);
  

+unlock_enable_sysfs: spin_unlock(&drvdata->spinlock); if (!ret) @@ -611,6 +664,9 @@ static void etm_disable_perf(struct coresight_device *csdev) coresight_disclaim_device_unlocked(csdev); CS_LOCK(drvdata->base);

• /* perf will release trace ids when _free_aux() is called at the end of the session */

Minor nit: Please split the line.

With that

Reviewed-by: Suzuki K Poulose suzuki.poulose@arm.com