[PATCH v2 2/3] perf/imx_ddr: adjust counter result after read cycle counter

[Xu Yang]

Because we initialize CP filed to shorten counter0 overflow time, the cycle
counter will start couting from a fixed/base value each time. We need to
remove the base from the result too. Therefore, we could get precise result
from cycle counter.

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

---
Changes in v2:
 - improve if condition
---
 drivers/perf/fsl_imx8_ddr_perf.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/perf/fsl_imx8_ddr_perf.c b/drivers/perf/fsl_imx8_ddr_perf.c
index 039069756bbc..d65200d4e96e 100644
--- a/drivers/perf/fsl_imx8_ddr_perf.c
+++ b/drivers/perf/fsl_imx8_ddr_perf.c
@@ -481,6 +481,12 @@ static void ddr_perf_event_update(struct perf_event *event)
 	int ret;
 
 	new_raw_count = ddr_perf_read_counter(pmu, counter);
+	/* Workaround for i.MX8MP */
+	if (pmu->devtype_data->quirks & DDR_CAP_AXI_ID_FILTER_ENHANCED) {
+		if (counter == EVENT_CYCLES_COUNTER)
+			new_raw_count -= 0xF0000000;
+	}
+
 	local64_add(new_raw_count, &event->count);
 
 	/*
-- 
2.34.1