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drm/i915/selftest: Fix engine timestamp and ktime disparity

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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 <chris.p.wilson@intel.com>
Signed-off-by: Anshuman Gupta <anshuman.gupta@intel.com>
Reviewed-by: Badal Nilawar <badal.nilawar@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230223100503.3323627-2-anshuman.gupta@intel.com
This commit is contained in:
Anshuman Gupta
2023-02-23 15:35:02 +05:30
parent 5060060557
commit 29b41cf707
2 changed files with 3 additions and 3 deletions
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2
drivers/gpu/drm/i915/gt/selftest_gt_pm.c
View File

@@ -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();
}

4
drivers/gpu/drm/i915/gt/selftest_rps.c
View File

@@ -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();
}