diff options
| author | Joakim Zhang <qiangqing.zhang@nxp.com> | 2020-02-25 20:56:43 +0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-03-25 08:25:47 +0100 |
| commit | 1002a094e066f4e87d78022227b387138bfb0f0f (patch) | |
| tree | cb1f9ac8d55f29322ae6b1be13d879ee22d448cf /drivers/perf | |
| parent | 0f6ae2cba3b834f3bfaf476f5989679362ec1ad7 (diff) | |
drivers/perf: fsl_imx8_ddr: Correct the CLEAR bit definition
[ Upstream commit 049d919168458ac54e7fad27cd156a958b042d2f ]
When disabling a counter from ddr_perf_event_stop(), the counter value
is reset to 0 at the same time.
Preserve the counter value by performing a read-modify-write of the
PMU register and clearing only the enable bit.
Signed-off-by: Joakim Zhang <qiangqing.zhang@nxp.com>
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'drivers/perf')
| -rw-r--r-- | drivers/perf/fsl_imx8_ddr_perf.c | 10 |
1 files changed, 6 insertions, 4 deletions
diff --git a/drivers/perf/fsl_imx8_ddr_perf.c b/drivers/perf/fsl_imx8_ddr_perf.c index 0e51baa48b14..6eef47de8fcc 100644 --- a/drivers/perf/fsl_imx8_ddr_perf.c +++ b/drivers/perf/fsl_imx8_ddr_perf.c @@ -327,9 +327,10 @@ static void ddr_perf_counter_enable(struct ddr_pmu *pmu, int config, if (enable) { /* - * must disable first, then enable again - * otherwise, cycle counter will not work - * if previous state is enabled. + * cycle counter is special which should firstly write 0 then + * write 1 into CLEAR bit to clear it. Other counters only + * need write 0 into CLEAR bit and it turns out to be 1 by + * hardware. Below enable flow is harmless for all counters. */ writel(0, pmu->base + reg); val = CNTL_EN | CNTL_CLEAR; @@ -337,7 +338,8 @@ static void ddr_perf_counter_enable(struct ddr_pmu *pmu, int config, writel(val, pmu->base + reg); } else { /* Disable counter */ - writel(0, pmu->base + reg); + val = readl_relaxed(pmu->base + reg) & CNTL_EN_MASK; + writel(val, pmu->base + reg); } } |