[PATCH v3 08/13] coresight: tmc-etr: Relax collection of trace from sysfs mode

Suzuki K Poulose
2018-07-26T12:55:16Z

Since the ETR now uses mode specific buffers, we can reliably
provide the trace data captured in sysfs mode, even when the ETR
is operating in PERF mode.

Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
---
drivers/hwtracing/coresight/coresight-tmc-etr.c | 14 ++++++--------
1 file changed, 6 insertions(+), 8 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c b/drivers/hwtracing/coresight/coresight-tmc-etr.c
index 58c7935..671a2ba 100644
--- a/drivers/hwtracing/coresight/coresight-tmc-etr.c
+++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c
@@ -1168,19 +1168,17 @@ int tmc_read_prepare_etr(struct tmc_drvdata *drvdata)
goto out;
}

- /* Don't interfere if operated from Perf */
- if (drvdata->mode == CS_MODE_PERF) {
- ret = -EINVAL;
- goto out;
- }
-
- /* If sysfs_buf is NULL the trace data has been read already */
+ /*
+ * We can safely allow reads even if the ETR is operating in PERF mode,
+ * since the sysfs session is captured in mode specific data.
+ * If drvdata::sysfs_data is NULL the trace data has been read already.
+ */
if (!drvdata->sysfs_buf) {
ret = -EINVAL;
goto out;
}

- /* Disable the TMC if we are trying to read from a running session */
+ /* Disable the TMC if we are trying to read from a running session. */
if (drvdata->mode == CS_MODE_SYSFS)
tmc_etr_disable_hw(drvdata);

--
2.7.4