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coresight: tmc-etr: Properly set AUX buffer head in snapshot mode

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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>
This commit is contained in:
Mathieu Poirier 2019-06-19 11:29:06 -06:00 committed by Greg Kroah-Hartman
parent 514e5150e7
commit 3ecb03022a
1 changed files with 5 additions and 6 deletions
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11
drivers/hwtracing/coresight/coresight-tmc-etr.c
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@ -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: