linux-kernel - [PATCH v2 13/17] coresight: trbe: Add a helper to determine the minimum buffer size

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Message-Id: <20210921134121.2423546-14-suzuki.poulose@arm.com>
Date:   Tue, 21 Sep 2021 14:41:17 +0100
From:   Suzuki K Poulose <suzuki.poulose@....com>
To:     linux-arm-kernel@...ts.infradead.org
Cc:     linux-kernel@...r.kernel.org, maz@...nel.org,
        catalin.marinas@....com, mark.rutland@....com, james.morse@....com,
        anshuman.khandual@....com, leo.yan@...aro.org,
        mike.leach@...aro.org, mathieu.poirier@...aro.org, will@...nel.org,
        lcherian@...vell.com, coresight@...ts.linaro.org,
        Suzuki K Poulose <suzuki.poulose@....com>
Subject: [PATCH v2 13/17] 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@....com>
Cc: Mike Leach <mike.leach@...aro.org>
Cc: Mathieu Poirier <mathieu.poirier@...aro.org>
Cc: Leo Yan <leo.yan@...aro.org>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@....com>
---
 drivers/hwtracing/coresight/coresight-trbe.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/hwtracing/coresight/coresight-trbe.c b/drivers/hwtracing/coresight/coresight-trbe.c
index 797d978f9fa7..3373f4e2183b 100644
--- a/drivers/hwtracing/coresight/coresight-trbe.c
+++ b/drivers/hwtracing/coresight/coresight-trbe.c
@@ -277,6 +277,11 @@ trbe_handle_to_cpudata(struct perf_output_handle *handle)
 	return buf->cpudata;
 }
 
+static u64 trbe_min_trace_buf_size(struct perf_output_handle *handle)
+{
+	return TRBE_TRACE_MIN_BUF_SIZE;
+}
+
 /*
  * TRBE Limit Calculation
  *
@@ -447,7 +452,7 @@ 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);
 	}
-- 
2.24.1