drm/i915/gt: Delete the live_hearbeat_fast selftest

The test is trying to push the heartbeat frequency to the limit, which
might sometimes fail. Such a failure does not provide valuable
information, because it does not indicate that there is something
necessarily wrong with either the driver or the hardware.

Remove the test to prevent random, unnecessary failures from appearing
in CI.

Suggested-by: Chris Wilson <chris.p.wilson@intel.com>
Signed-off-by: Niemiec, Krzysztof <krzysztof.niemiec@intel.com>
Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com>
Signed-off-by: Andi Shyti <andi.shyti@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/fe2vu5h7v7ooxbhwpbfsypxg5mjrnt56gc3cgrqpnhgrgce334@qfrv2skxrp47

drivers/gpu/drm/i915/gt/selftest_engine_heartbeat.c

@@ -193,115 +193,6 @@ static int live_idle_pulse(void *arg)
 	return err;
 }
 
-static int cmp_u32(const void *_a, const void *_b)
-{
-	const u32 *a = _a, *b = _b;
-
-	return *a - *b;
-}
-
-static int __live_heartbeat_fast(struct intel_engine_cs *engine)
-{
-	const unsigned int error_threshold = max(20000u, jiffies_to_usecs(6));
-	struct intel_context *ce;
-	struct i915_request *rq;
-	ktime_t t0, t1;
-	u32 times[5];
-	int err;
-	int i;
-
-	ce = intel_context_create(engine);
-	if (IS_ERR(ce))
-		return PTR_ERR(ce);
-
-	intel_engine_pm_get(engine);
-
-	err = intel_engine_set_heartbeat(engine, 1);
-	if (err)
-		goto err_pm;
-
-	for (i = 0; i < ARRAY_SIZE(times); i++) {
-		do {
-			/* Manufacture a tick */
-			intel_engine_park_heartbeat(engine);
-			GEM_BUG_ON(engine->heartbeat.systole);
-			engine->serial++; /*  pretend we are not idle! */
-			intel_engine_unpark_heartbeat(engine);
-
-			flush_delayed_work(&engine->heartbeat.work);
-			if (!delayed_work_pending(&engine->heartbeat.work)) {
-				pr_err("%s: heartbeat %d did not start\n",
-				       engine->name, i);
-				err = -EINVAL;
-				goto err_pm;
-			}
-
-			rcu_read_lock();
-			rq = READ_ONCE(engine->heartbeat.systole);
-			if (rq)
-				rq = i915_request_get_rcu(rq);
-			rcu_read_unlock();
-		} while (!rq);
-
-		t0 = ktime_get();
-		while (rq == READ_ONCE(engine->heartbeat.systole))
-			yield(); /* work is on the local cpu! */
-		t1 = ktime_get();
-
-		i915_request_put(rq);
-		times[i] = ktime_us_delta(t1, t0);
-	}
-
-	sort(times, ARRAY_SIZE(times), sizeof(times[0]), cmp_u32, NULL);
-
-	pr_info("%s: Heartbeat delay: %uus [%u, %u]\n",
-		engine->name,
-		times[ARRAY_SIZE(times) / 2],
-		times[0],
-		times[ARRAY_SIZE(times) - 1]);
-
-	/*
-	 * Ideally, the upper bound on min work delay would be something like
-	 * 2 * 2 (worst), +1 for scheduling, +1 for slack. In practice, we
-	 * are, even with system_wq_highpri, at the mercy of the CPU scheduler
-	 * and may be stuck behind some slow work for many millisecond. Such
-	 * as our very own display workers.
-	 */
-	if (times[ARRAY_SIZE(times) / 2] > error_threshold) {
-		pr_err("%s: Heartbeat delay was %uus, expected less than %dus\n",
-		       engine->name,
-		       times[ARRAY_SIZE(times) / 2],
-		       error_threshold);
-		err = -EINVAL;
-	}
-
-	reset_heartbeat(engine);
-err_pm:
-	intel_engine_pm_put(engine);
-	intel_context_put(ce);
-	return err;
-}
-
-static int live_heartbeat_fast(void *arg)
-{
-	struct intel_gt *gt = arg;
-	struct intel_engine_cs *engine;
-	enum intel_engine_id id;
-	int err = 0;
-
-	/* Check that the heartbeat ticks at the desired rate. */
-	if (!CONFIG_DRM_I915_HEARTBEAT_INTERVAL)
-		return 0;
-
-	for_each_engine(engine, gt, id) {
-		err = __live_heartbeat_fast(engine);
-		if (err)
-			break;
-	}
-
-	return err;
-}
-
 static int __live_heartbeat_off(struct intel_engine_cs *engine)
 {
 	int err;
@@ -372,7 +263,6 @@ int intel_heartbeat_live_selftests(struct drm_i915_private *i915)
 	static const struct i915_subtest tests[] = {
 		SUBTEST(live_idle_flush),
 		SUBTEST(live_idle_pulse),
-		SUBTEST(live_heartbeat_fast),
 		SUBTEST(live_heartbeat_off),
 	};
 	int saved_hangcheck;