perf cs-etm: Start reading 'Z' --itrace option

Recently the 'Z' --itrace option was added to override detection
of timeless decoding. This is also useful in Coresight to work around
issues with invalid timestamps on some hardware.

When the 'Z' option is provided, the existing timeless decoding mode
will be used, even if timestamps were recorded.

Signed-off-by: James Clark <james.clark@arm.com>
Reviewed-by: Leo Yan <leo.yan@linaro.org>
Cc: Al Grant <al.grant@arm.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Branislav Rankov <branislav.rankov@arm.com>
Cc: Denis Nikitin <denik@chromium.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: John Garry <john.garry@huawei.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Mike Leach <mike.leach@linaro.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Suzuki Poulouse <suzuki.poulose@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: coresight@lists.linaro.org
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lore.kernel.org/lkml/20210517131741.3027-3-james.clark@arm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/cs-etm.c

@@ -2473,6 +2473,10 @@ static bool cs_etm__is_timeless_decoding(struct cs_etm_auxtrace *etm)
 	struct evlist *evlist = etm->session->evlist;
 	bool timeless_decoding = true;
 
+	/* Override timeless mode with user input from --itrace=Z */
+	if (etm->synth_opts.timeless_decoding)
+		return true;
+
 	/*
 	 * Circle through the list of event and complain if we find one
 	 * with the time bit set.