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authorMathieu Poirier <mathieu.poirier@linaro.org>2019-06-19 11:29:06 -0600
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2019-06-19 20:29:13 +0200
commit3ecb03022a25b3f089b93a35f608ea7ee6a244aa (patch)
tree4947be32cfca46316b3feade696685bee9f2b345
parent514e5150e7c6b247d7a473f935fc49d6f194688b (diff)
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coresight: tmc-etr: Properly set AUX buffer head in snapshot mode
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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--drivers/hwtracing/coresight/coresight-tmc-etr.c11
1 files changed, 5 insertions, 6 deletions
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: