From 29b41cf707b5ecc55cab12bfa04fbd9811f4fd04 Mon Sep 17 00:00:00 2001 From: Anshuman Gupta Date: Thu, 23 Feb 2023 15:35:02 +0530 Subject: [PATCH] drm/i915/selftest: Fix engine timestamp and ktime disparity While reading the engine timestamps there can be uncontrollable concurrent mmio access via other i915 child drivers and by GuC, which is not truly atomic context as expected by this selftest, which may cause mmio latency to read the engine timestamps, Account such latency to calculate time to read engine timestamp such that selftest can validate the timestamp and ktime pair. Cc: Chris Wilson Signed-off-by: Anshuman Gupta Reviewed-by: Badal Nilawar Link: https://patchwork.freedesktop.org/patch/msgid/20230223100503.3323627-2-anshuman.gupta@intel.com --- drivers/gpu/drm/i915/gt/selftest_gt_pm.c | 2 +- drivers/gpu/drm/i915/gt/selftest_rps.c | 4 ++-- 2 files changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/gpu/drm/i915/gt/selftest_gt_pm.c b/drivers/gpu/drm/i915/gt/selftest_gt_pm.c index b46425aeb2f04..0971241707ce8 100644 --- a/drivers/gpu/drm/i915/gt/selftest_gt_pm.c +++ b/drivers/gpu/drm/i915/gt/selftest_gt_pm.c @@ -63,8 +63,8 @@ static void measure_clocks(struct intel_engine_cs *engine, udelay(1000); - dt[i] = ktime_sub(ktime_get(), dt[i]); cycles[i] += read_timestamp(engine); + dt[i] = ktime_sub(ktime_get(), dt[i]); local_irq_enable(); } diff --git a/drivers/gpu/drm/i915/gt/selftest_rps.c b/drivers/gpu/drm/i915/gt/selftest_rps.c index 6755bbc4ebdac..c0cc0dd78c7c8 100644 --- a/drivers/gpu/drm/i915/gt/selftest_rps.c +++ b/drivers/gpu/drm/i915/gt/selftest_rps.c @@ -299,13 +299,13 @@ int live_rps_clock_interval(void *arg) for (i = 0; i < 5; i++) { preempt_disable(); - dt_[i] = ktime_get(); cycles_[i] = -intel_uncore_read_fw(gt->uncore, GEN6_RP_CUR_UP_EI); + dt_[i] = ktime_get(); udelay(1000); - dt_[i] = ktime_sub(ktime_get(), dt_[i]); cycles_[i] += intel_uncore_read_fw(gt->uncore, GEN6_RP_CUR_UP_EI); + dt_[i] = ktime_sub(ktime_get(), dt_[i]); preempt_enable(); } -- 2.30.2