From e89ecd8368860bf05437eabd07d292c316221cfc Mon Sep 17 00:00:00 2001 From: Xu Yang Date: Fri, 11 Aug 2023 09:54:37 +0800 Subject: perf/imx_ddr: speed up overflow frequency of cycle For i.MX8MP, we cannot ensure that cycle counter overflow occurs at least 4 times as often as other events. Due to byte counters will count for any event configured, it will overflow more often. And if byte counters overflow that related counters would stop since they share the COUNTER_CNTL. We can speed up cycle counter overflow frequency by setting counter parameter (CP) field of cycle counter. In this way, we can avoid stop counting byte counters when interrupt didn't come and the byte counters can be fetched or updated from each cycle counter overflow interrupt. 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 Reviewed-by: Frank Li Link: https://lore.kernel.org/r/20230811015438.1999307-1-xu.yang_2@nxp.com Signed-off-by: Will Deacon --- drivers/perf/fsl_imx8_ddr_perf.c | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) (limited to 'drivers/perf') diff --git a/drivers/perf/fsl_imx8_ddr_perf.c b/drivers/perf/fsl_imx8_ddr_perf.c index 1cb3861ab0e0..7d4e49565738 100644 --- a/drivers/perf/fsl_imx8_ddr_perf.c +++ b/drivers/perf/fsl_imx8_ddr_perf.c @@ -27,6 +27,8 @@ #define CNTL_CLEAR_MASK 0xFFFFFFFD #define CNTL_OVER_MASK 0xFFFFFFFE +#define CNTL_CP_SHIFT 16 +#define CNTL_CP_MASK (0xFF << CNTL_CP_SHIFT) #define CNTL_CSV_SHIFT 24 #define CNTL_CSV_MASK (0xFFU << CNTL_CSV_SHIFT) @@ -34,6 +36,8 @@ #define EVENT_CYCLES_COUNTER 0 #define NUM_COUNTERS 4 +/* For removing bias if cycle counter CNTL.CP is set to 0xf0 */ +#define CYCLES_COUNTER_MASK 0x0FFFFFFF #define AXI_MASKING_REVERT 0xffff0000 /* AXI_MASKING(MSB 16bits) + AXI_ID(LSB 16bits) */ #define to_ddr_pmu(p) container_of(p, struct ddr_pmu, pmu) @@ -426,6 +430,17 @@ static void ddr_perf_counter_enable(struct ddr_pmu *pmu, int config, writel(0, pmu->base + reg); val = CNTL_EN | CNTL_CLEAR; val |= FIELD_PREP(CNTL_CSV_MASK, config); + + /* + * On i.MX8MP we need to bias the cycle counter to overflow more often. + * We do this by initializing bits [23:16] of the counter value via the + * COUNTER_CTRL Counter Parameter (CP) field. + */ + if (pmu->devtype_data->quirks & DDR_CAP_AXI_ID_FILTER_ENHANCED) { + if (counter == EVENT_CYCLES_COUNTER) + val |= FIELD_PREP(CNTL_CP_MASK, 0xf0); + } + writel(val, pmu->base + reg); } else { /* Disable counter */ @@ -465,6 +480,12 @@ static void ddr_perf_event_update(struct perf_event *event) int ret; new_raw_count = ddr_perf_read_counter(pmu, counter); + /* Remove the bias applied in ddr_perf_counter_enable(). */ + if (pmu->devtype_data->quirks & DDR_CAP_AXI_ID_FILTER_ENHANCED) { + if (counter == EVENT_CYCLES_COUNTER) + new_raw_count &= CYCLES_COUNTER_MASK; + } + local64_add(new_raw_count, &event->count); /* -- cgit v1.2.3