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coresight: tmc-etf: 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 11:29:07 -06:00 committed by Greg Kroah-Hartman
parent 3ecb03022a
commit 0402f75efe
1 changed files with 9 additions and 5 deletions
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14
drivers/hwtracing/coresight/coresight-tmc-etf.c
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@ -542,11 +542,15 @@ static unsigned long tmc_update_etf_buffer(struct coresight_device *csdev,
}
}
/* In snapshot mode we have to update the head */
if (buf->snapshot) {
handle->head = (cur * PAGE_SIZE) + offset;
to_read = buf->nr_pages << PAGE_SHIFT;
}
/*
* 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 (buf->snapshot)
handle->head += to_read;
CS_LOCK(drvdata->base);
out:
spin_unlock_irqrestore(&drvdata->spinlock, flags);