PMU and sysfs use different wakeref's to "interpret" zero freq. Sysfs uses runtime PM wakeref (see intel_rps_read_punit_req and intel_rps_read_actual_frequency). PMU uses the GT parked/unparked wakeref. In general the GT wakeref is held for less time that the runtime PM wakeref which causes PMU to report a lower average freq than the average freq obtained from sampling sysfs.
To resolve this, use the same freq functions (and wakeref's) in PMU as those used in sysfs. Bug: https://gitlab.freedesktop.org/drm/intel/-/issues/7025 Reported-by: Ashwin Kumar Kulkarni <ashwin.kumar.kulka...@intel.com> Cc: Tvrtko Ursulin <tvrtko.ursu...@linux.intel.com> Signed-off-by: Ashutosh Dixit <ashutosh.di...@intel.com> --- drivers/gpu/drm/i915/i915_pmu.c | 27 ++------------------------- 1 file changed, 2 insertions(+), 25 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_pmu.c b/drivers/gpu/drm/i915/i915_pmu.c index 958b37123bf1..eda03f264792 100644 --- a/drivers/gpu/drm/i915/i915_pmu.c +++ b/drivers/gpu/drm/i915/i915_pmu.c @@ -371,37 +371,16 @@ static void frequency_sample(struct intel_gt *gt, unsigned int period_ns) { struct drm_i915_private *i915 = gt->i915; - struct intel_uncore *uncore = gt->uncore; struct i915_pmu *pmu = &i915->pmu; struct intel_rps *rps = >->rps; if (!frequency_sampling_enabled(pmu)) return; - /* Report 0/0 (actual/requested) frequency while parked. */ - if (!intel_gt_pm_get_if_awake(gt)) - return; - if (pmu->enable & config_mask(I915_PMU_ACTUAL_FREQUENCY)) { - u32 val; - - /* - * We take a quick peek here without using forcewake - * so that we don't perturb the system under observation - * (forcewake => !rc6 => increased power use). We expect - * that if the read fails because it is outside of the - * mmio power well, then it will return 0 -- in which - * case we assume the system is running at the intended - * frequency. Fortunately, the read should rarely fail! - */ - val = intel_uncore_read_fw(uncore, GEN6_RPSTAT1); - if (val) - val = intel_rps_get_cagf(rps, val); - else - val = rps->cur_freq; - add_sample_mult(&pmu->sample[__I915_SAMPLE_FREQ_ACT], - intel_gpu_freq(rps, val), period_ns / 1000); + intel_rps_read_actual_frequency(rps), + period_ns / 1000); } if (pmu->enable & config_mask(I915_PMU_REQUESTED_FREQUENCY)) { @@ -409,8 +388,6 @@ frequency_sample(struct intel_gt *gt, unsigned int period_ns) intel_rps_get_requested_frequency(rps), period_ns / 1000); } - - intel_gt_pm_put_async(gt); } static enum hrtimer_restart i915_sample(struct hrtimer *hrtimer) -- 2.34.1
