coresight: trbe: Add a helper to determine the minimum buffer size

For the TRBE to operate, we need a minimum space available to collect
meaningful trace session. This is currently a few bytes, but we may need
to extend this for working around errata. So, abstract this into a helper
function.

Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Mike Leach <mike.leach@linaro.org>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Leo Yan <leo.yan@linaro.org>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20211019163153.3692640-12-suzuki.poulose@arm.com
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>

diff --git a/drivers/hwtracing/coresight/coresight-trbe.c b/drivers/hwtracing/coresight/coresight-trbe.c
index 2d39e5e..02a639e 100644 (file)
--- a/drivers/hwtracing/coresight/coresight-trbe.c
+++ b/drivers/hwtracing/coresight/coresight-trbe.c
@@ -303,6 +303,11 @@ static unsigned long trbe_snapshot_offset(struct perf_output_handle *handle)
        return buf->nr_pages * PAGE_SIZE;
 }
 
+static u64 trbe_min_trace_buf_size(struct perf_output_handle *handle)
+{
+       return TRBE_TRACE_MIN_BUF_SIZE;
+}
+
 /*
  * TRBE Limit Calculation
  *
@@ -473,7 +478,7 @@ static unsigned long trbe_normal_offset(struct perf_output_handle *handle)
         * have space for a meaningful run, we rather pad it
         * and start fresh.
         */
-       if (limit && (limit - head < TRBE_TRACE_MIN_BUF_SIZE)) {
+       if (limit && ((limit - head) < trbe_min_trace_buf_size(handle))) {
                trbe_pad_buf(handle, limit - head);
                limit = __trbe_normal_offset(handle);
        }