drm/i915/selftests: Exercise basic RPS interrupt generation

Since we depend upon RPS generating interrupts after evaluation
intervals to determine when to up/down clock the GPU, it is imperative
that we successfully enable interrupt generation! Verify that we do see
an interrupt if we keep the GPU busy for an entire EI.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Andi Shyti <andi.shyti@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200415170318.16771-1-chris@chris-wilson.co.uk

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

@@ -1923,3 +1923,7 @@ bool i915_gpu_turbo_disable(void)
 	return ret;
 }
 EXPORT_SYMBOL_GPL(i915_gpu_turbo_disable);
+
+#if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
+#include "selftest_rps.c"
+#endif

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

@@ -7,6 +7,7 @@
 
 #include "selftest_llc.h"
 #include "selftest_rc6.h"
+#include "selftest_rps.h"
 
 static int live_gt_resume(void *arg)
 {
@@ -52,6 +53,7 @@ int intel_gt_pm_live_selftests(struct drm_i915_private *i915)
 {
 	static const struct i915_subtest tests[] = {
 		SUBTEST(live_rc6_manual),
+		SUBTEST(live_rps_interrupt),
 		SUBTEST(live_gt_resume),
 	};
 

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

@@ -0,0 +1,223 @@
+// SPDX-License-Identifier: MIT
+/*
+ * Copyright © 2020 Intel Corporation
+ */
+
+#include "intel_engine_pm.h"
+#include "intel_gt_pm.h"
+#include "intel_rc6.h"
+#include "selftest_rps.h"
+#include "selftests/igt_flush_test.h"
+#include "selftests/igt_spinner.h"
+
+static void dummy_rps_work(struct work_struct *wrk)
+{
+}
+
+static int __rps_up_interrupt(struct intel_rps *rps,
+			      struct intel_engine_cs *engine,
+			      struct igt_spinner *spin)
+{
+	struct intel_uncore *uncore = engine->uncore;
+	struct i915_request *rq;
+	u32 timeout;
+
+	if (!intel_engine_can_store_dword(engine))
+		return 0;
+
+	intel_gt_pm_wait_for_idle(engine->gt);
+	GEM_BUG_ON(rps->active);
+
+	rps->pm_iir = 0;
+	rps->cur_freq = rps->min_freq;
+
+	rq = igt_spinner_create_request(spin, engine->kernel_context, MI_NOOP);
+	if (IS_ERR(rq))
+		return PTR_ERR(rq);
+
+	i915_request_get(rq);
+	i915_request_add(rq);
+
+	if (!igt_wait_for_spinner(spin, rq)) {
+		pr_err("%s: RPS spinner did not start\n",
+		       engine->name);
+		i915_request_put(rq);
+		intel_gt_set_wedged(engine->gt);
+		return -EIO;
+	}
+
+	if (!rps->active) {
+		pr_err("%s: RPS not enabled on starting spinner\n",
+		       engine->name);
+		igt_spinner_end(spin);
+		i915_request_put(rq);
+		return -EINVAL;
+	}
+
+	if (!(rps->pm_events & GEN6_PM_RP_UP_THRESHOLD)) {
+		pr_err("%s: RPS did not register UP interrupt\n",
+		       engine->name);
+		i915_request_put(rq);
+		return -EINVAL;
+	}
+
+	if (rps->last_freq != rps->min_freq) {
+		pr_err("%s: RPS did not program min frequency\n",
+		       engine->name);
+		i915_request_put(rq);
+		return -EINVAL;
+	}
+
+	timeout = intel_uncore_read(uncore, GEN6_RP_UP_EI);
+	timeout = GT_PM_INTERVAL_TO_US(engine->i915, timeout);
+
+	usleep_range(2 * timeout, 3 * timeout);
+	GEM_BUG_ON(i915_request_completed(rq));
+
+	igt_spinner_end(spin);
+	i915_request_put(rq);
+
+	if (rps->cur_freq != rps->min_freq) {
+		pr_err("%s: Frequency unexpectedly changed [up], now %d!\n",
+		       engine->name, intel_rps_read_actual_frequency(rps));
+		return -EINVAL;
+	}
+
+	if (!(rps->pm_iir & GEN6_PM_RP_UP_THRESHOLD)) {
+		pr_err("%s: UP interrupt not recorded for spinner, pm_iir:%x, prev_up:%x, up_threshold:%x, up_ei:%x\n",
+		       engine->name, rps->pm_iir,
+		       intel_uncore_read(uncore, GEN6_RP_PREV_UP),
+		       intel_uncore_read(uncore, GEN6_RP_UP_THRESHOLD),
+		       intel_uncore_read(uncore, GEN6_RP_UP_EI));
+		return -EINVAL;
+	}
+
+	intel_gt_pm_wait_for_idle(engine->gt);
+	return 0;
+}
+
+static int __rps_down_interrupt(struct intel_rps *rps,
+				struct intel_engine_cs *engine)
+{
+	struct intel_uncore *uncore = engine->uncore;
+	u32 timeout;
+
+	mutex_lock(&rps->lock);
+	GEM_BUG_ON(!rps->active);
+	intel_rps_set(rps, rps->max_freq);
+	mutex_unlock(&rps->lock);
+
+	if (!(rps->pm_events & GEN6_PM_RP_DOWN_THRESHOLD)) {
+		pr_err("%s: RPS did not register DOWN interrupt\n",
+		       engine->name);
+		return -EINVAL;
+	}
+
+	if (rps->last_freq != rps->max_freq) {
+		pr_err("%s: RPS did not program max frequency\n",
+		       engine->name);
+		return -EINVAL;
+	}
+
+	timeout = intel_uncore_read(uncore, GEN6_RP_DOWN_EI);
+	timeout = GT_PM_INTERVAL_TO_US(engine->i915, timeout);
+
+	/* Flush any previous EI */
+	usleep_range(timeout, 2 * timeout);
+
+	/* Reset the interrupt status */
+	rps_disable_interrupts(rps);
+	GEM_BUG_ON(rps->pm_iir);
+	rps_enable_interrupts(rps);
+
+	/* And then wait for the timeout, for real this time */
+	usleep_range(2 * timeout, 3 * timeout);
+
+	if (rps->cur_freq != rps->max_freq) {
+		pr_err("%s: Frequency unexpectedly changed [down], now %d!\n",
+		       engine->name,
+		       intel_rps_read_actual_frequency(rps));
+		return -EINVAL;
+	}
+
+	if (!(rps->pm_iir & (GEN6_PM_RP_DOWN_THRESHOLD | GEN6_PM_RP_DOWN_TIMEOUT))) {
+		pr_err("%s: DOWN interrupt not recorded for idle, pm_iir:%x, prev_down:%x, down_threshold:%x, down_ei:%x [prev_up:%x, up_threshold:%x, up_ei:%x]\n",
+		       engine->name, rps->pm_iir,
+		       intel_uncore_read(uncore, GEN6_RP_PREV_DOWN),
+		       intel_uncore_read(uncore, GEN6_RP_DOWN_THRESHOLD),
+		       intel_uncore_read(uncore, GEN6_RP_DOWN_EI),
+		       intel_uncore_read(uncore, GEN6_RP_PREV_UP),
+		       intel_uncore_read(uncore, GEN6_RP_UP_THRESHOLD),
+		       intel_uncore_read(uncore, GEN6_RP_UP_EI));
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+int live_rps_interrupt(void *arg)
+{
+	struct intel_gt *gt = arg;
+	struct intel_rps *rps = &gt->rps;
+	void (*saved_work)(struct work_struct *wrk);
+	struct intel_engine_cs *engine;
+	enum intel_engine_id id;
+	struct igt_spinner spin;
+	u32 pm_events;
+	int err = 0;
+
+	/*
+	 * First, let's check whether or not we are receiving interrupts.
+	 */
+
+	if (!rps->enabled || rps->max_freq <= rps->min_freq)
+		return 0;
+
+	intel_gt_pm_get(gt);
+	pm_events = rps->pm_events;
+	intel_gt_pm_put(gt);
+	if (!pm_events) {
+		pr_err("No RPS PM events registered, but RPS is enabled?\n");
+		return -ENODEV;
+	}
+
+	if (igt_spinner_init(&spin, gt))
+		return -ENOMEM;
+
+	intel_gt_pm_wait_for_idle(gt);
+	saved_work = rps->work.func;
+	rps->work.func = dummy_rps_work;
+
+	for_each_engine(engine, gt, id) {
+		/* Keep the engine busy with a spinner; expect an UP! */
+		if (pm_events & GEN6_PM_RP_UP_THRESHOLD) {
+			err = __rps_up_interrupt(rps, engine, &spin);
+			if (err)
+				goto out;
+		}
+
+		/* Keep the engine awake but idle and check for DOWN */
+		if (pm_events & GEN6_PM_RP_DOWN_THRESHOLD) {
+			intel_engine_pm_get(engine);
+			intel_rc6_disable(&gt->rc6);
+
+			err = __rps_down_interrupt(rps, engine);
+
+			intel_rc6_enable(&gt->rc6);
+			intel_engine_pm_put(engine);
+			if (err)
+				goto out;
+		}
+	}
+
+out:
+	if (igt_flush_test(gt->i915))
+		err = -EIO;
+
+	igt_spinner_fini(&spin);
+
+	intel_gt_pm_wait_for_idle(gt);
+	rps->work.func = saved_work;
+
+	return err;
+}

drivers/gpu/drm/i915/gt/selftest_rps.h

@@ -0,0 +1,11 @@
+/* SPDX-License-Identifier: MIT */
+/*
+ * Copyright © 2020 Intel Corporation
+ */
+
+#ifndef SELFTEST_RPS_H
+#define SELFTEST_RPS_H
+
+int live_rps_interrupt(void *arg);
+
+#endif /* SELFTEST_RPS_H */