linux-kernel - [PATCH v6 5/7] perf: imx_perf: fix counter start and config sequence

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Date: Thu,  7 Mar 2024 17:57:28 +0800
From: Xu Yang <xu.yang_2@....com>
To: Frank.li@....com,
	will@...nel.org,
	mark.rutland@....com,
	robh+dt@...nel.org,
	krzysztof.kozlowski+dt@...aro.org,
	conor+dt@...nel.org,
	shawnguo@...nel.org,
	s.hauer@...gutronix.de,
	kernel@...gutronix.de,
	festevam@...il.com,
	john.g.garry@...cle.com,
	jolsa@...nel.org,
	namhyung@...nel.org,
	irogers@...gle.com
Cc: mike.leach@...aro.org,
	peterz@...radead.org,
	mingo@...hat.com,
	acme@...nel.org,
	alexander.shishkin@...ux.intel.com,
	adrian.hunter@...el.com,
	linux-arm-kernel@...ts.infradead.org,
	devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-perf-users@...r.kernel.org,
	imx@...ts.linux.dev
Subject: [PATCH v6 5/7] perf: imx_perf: fix counter start and config sequence

In current driver, the counter will start firstly and then be configured.
This sequence is not correct for AXI filter events since the correct
AXI_MASK and AXI_ID are not set yet. Then the results may be inaccurate.

Signed-off-by: Xu Yang <xu.yang_2@....com>

---
Changes in v5:
 - new patch
Changes in v6:
 - no changes
---
 drivers/perf/fsl_imx9_ddr_perf.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/perf/fsl_imx9_ddr_perf.c b/drivers/perf/fsl_imx9_ddr_perf.c
index 4e8a3a4349c5..52234b97d0cb 100644
--- a/drivers/perf/fsl_imx9_ddr_perf.c
+++ b/drivers/perf/fsl_imx9_ddr_perf.c
@@ -543,12 +543,12 @@ static int ddr_perf_event_add(struct perf_event *event, int flags)
 	hwc->idx = counter;
 	hwc->state |= PERF_HES_STOPPED;
 
-	if (flags & PERF_EF_START)
-		ddr_perf_event_start(event, flags);
-
 	/* read trans, write trans, read beat */
 	imx93_ddr_perf_monitor_config(pmu, event_id, counter, cfg1, cfg2);
 
+	if (flags & PERF_EF_START)
+		ddr_perf_event_start(event, flags);
+
 	return 0;
 }
 
-- 
2.34.1