fix comments issues
Signed-off-by: Jerry Yu <jerry.h.yu@arm.com>
diff --git a/tests/suites/test_suite_platform.function b/tests/suites/test_suite_platform.function
index f4e12bf..2584d3d 100644
--- a/tests/suites/test_suite_platform.function
+++ b/tests/suites/test_suite_platform.function
@@ -86,8 +86,11 @@
elapsed_secs = mbedtls_time(NULL) - current;
/* Built-in mbedtls_time function returns the number of seconds since the
- * Epoch. That is affected by discontinuous jumps and cause test fail.
- * Workaround it with 1 seconds tollerance.
+ * Epoch. That is affected by discontinuous jumps. And `nanosleep` use
+ * CLOCK_MONOTONIC(monotonically-increasing time source), That will cause
+ * negative elapsed time difference.
+ *
+ * Workaround it with 1 second tolerance.
*/
TEST_ASSERT(elapsed_secs >= delay_secs - 1);
TEST_ASSERT(elapsed_secs < 4 + delay_secs);