linux-kernel - [PATCH v9 5/8] perf: imx_perf: fix counter start and config sequence

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Date: Mon, 15 Apr 2024 10:03:50 +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 v9 5/8] 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.

Reviewed-by: Frank Li <Frank.Li@....com>
Fixes: 55691f99d417 ("drivers/perf: imx_ddr: Add support for NXP i.MX9 SoC DDRC PMU driver")
cc: <stable@...r.kernel.org>
Signed-off-by: Xu Yang <xu.yang_2@....com>

---
Changes in v5:
 - new patch
Changes in v6:
 - no changes
Changes in v7:
 - no changes
Changes in v8:
 - add fix tag
Changes in v9:
 - add Rb tag
---
 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 1510502862fe..910fda7eb2c6 100644
--- a/drivers/perf/fsl_imx9_ddr_perf.c
+++ b/drivers/perf/fsl_imx9_ddr_perf.c
@@ -541,12 +541,12 @@ 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