From 7d29f0679d51e6503ebb0f409ebfec44a1da2062 Mon Sep 17 00:00:00 2001
From: Anshuman Gupta <anshuman.gupta@intel.com>
Date: Tue, 30 Nov 2021 18:50:05 +0530
Subject: drm/i915/selftest: Disable IRQ for timestamp calculation
Git-commit: 2ebc9e4af0291d2e8d14ecc0bad8f36de8cc6e62
Patch-mainline: v5.17-rc1
References: jsc#PED-1166 jsc#PED-1168 jsc#PED-1170 jsc#PED-1218 jsc#PED-1220 jsc#PED-1222 jsc#PED-1223 jsc#PED-1225
gt_pm selftest calculates engine ticks cycles and wall time
cycles by delta of respective engine elapsed TIMESTAMP and ktime
for period of 1000us.
It compares the engine ticks cycles with wall time cycles.
Disable local cpu interrupt so that interrupt handler does not
switch out the thread during measure_clocks() and prevent
miscalculation of engine tick cycles.
v2:
- nuke preempt_{disable,enable}, as disable_local_irq()
disable the preemption. (Chris)
Cc: Chris P Wilson <chris.p.wilson@intel.com>
Cc: Badal Nilawar <badal.nilawar@intel.com>
Cc: Ashutosh Dixit <ashutosh.dixit@intel.com>
Signed-off-by: Anshuman Gupta <anshuman.gupta@intel.com>
Reviewed-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211130132005.6305-1-anshuman.gupta@intel.com
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
drivers/gpu/drm/i915/gt/selftest_gt_pm.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/i915/gt/selftest_gt_pm.c b/drivers/gpu/drm/i915/gt/selftest_gt_pm.c
index b9441217ca3d..55c5cdb99f45 100644
--- a/drivers/gpu/drm/i915/gt/selftest_gt_pm.c
+++ b/drivers/gpu/drm/i915/gt/selftest_gt_pm.c
@@ -43,7 +43,7 @@ static void measure_clocks(struct intel_engine_cs *engine,
int i;
for (i = 0; i < 5; i++) {
- preempt_disable();
+ local_irq_disable();
cycles[i] = -ENGINE_READ_FW(engine, RING_TIMESTAMP);
dt[i] = ktime_get();
@@ -51,7 +51,7 @@ static void measure_clocks(struct intel_engine_cs *engine,
dt[i] = ktime_sub(ktime_get(), dt[i]);
cycles[i] += ENGINE_READ_FW(engine, RING_TIMESTAMP);
- preempt_enable();
+ local_irq_enable();
}
/* Use the median of both cycle/dt; close enough */
--
2.38.1