diff mbox series

[02/45] coresight: tmc-etr: Properly set AUX buffer head in snapshot mode

Message ID 20190619172949.4522-3-mathieu.poirier@linaro.org (mailing list archive)
State Mainlined, archived
Commit 3ecb03022a25b3f089b93a35f608ea7ee6a244aa
Headers show
Series coresight: next v5.2-rc5 | expand

Commit Message

Mathieu Poirier June 19, 2019, 5:29 p.m. UTC 
Unify amongst sink drivers how the AUX ring buffer head is communicated
to user space.  That way the same algorithm in user space can be used to
determine where the latest data is and how much of it to access.

Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Tested-by: Leo Yan <leo.yan@linaro.org>
---
 drivers/hwtracing/coresight/coresight-tmc-etr.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)
diff mbox series

Patch

diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c b/drivers/hwtracing/coresight/coresight-tmc-etr.c
index df6e4b0b84e9..cc8401c76c39 100644
--- a/drivers/hwtracing/coresight/coresight-tmc-etr.c
+++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c
@@ -1501,14 +1501,13 @@  tmc_update_etr_buffer(struct coresight_device *csdev,
 	tmc_etr_sync_perf_buffer(etr_perf);
 
 	/*
-	 * Update handle->head in snapshot mode. Also update the size to the
-	 * hardware buffer size if there was an overflow.
+	 * In snapshot mode we simply increment the head by the number of byte
+	 * that were written.  User space function  cs_etm_find_snapshot() will
+	 * figure out how many bytes to get from the AUX buffer based on the
+	 * position of the head.
 	 */
-	if (etr_perf->snapshot) {
+	if (etr_perf->snapshot)
 		handle->head += size;
-		if (etr_buf->full)
-			size = etr_buf->size;
-	}
 
 	lost |= etr_buf->full;
 out: