drm/i915/selftests: Split RPS frequency measurement

Split the frequency measurement into two modes, so that we can judge the
impact of the llc setup on top of the pure CS frequency scaling.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200420172739.11620-4-chris@chris-wilson.co.uk

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

@@ -54,7 +54,8 @@ int intel_gt_pm_live_selftests(struct drm_i915_private *i915)
 	static const struct i915_subtest tests[] = {
 		SUBTEST(live_rc6_manual),
 		SUBTEST(live_rps_control),
-		SUBTEST(live_rps_frequency),
+		SUBTEST(live_rps_frequency_cs),
+		SUBTEST(live_rps_frequency_srm),
 		SUBTEST(live_rps_power),
 		SUBTEST(live_rps_interrupt),
 		SUBTEST(live_gt_resume),

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

@@ -33,6 +33,7 @@ static int cmp_u64(const void *A, const void *B)
 static struct i915_vma *
 create_spin_counter(struct intel_engine_cs *engine,
 		    struct i915_address_space *vm,
+		    bool srm,
 		    u32 **cancel,
 		    u32 **counter)
 {
@@ -91,10 +92,12 @@ create_spin_counter(struct intel_engine_cs *engine,
 	*cs++ = MI_MATH_ADD;
 	*cs++ = MI_MATH_STORE(MI_MATH_REG(COUNT), MI_MATH_REG_ACCU);
 
+	if (srm) {
 		*cs++ = MI_STORE_REGISTER_MEM_GEN8;
 		*cs++ = i915_mmio_reg_offset(CS_GPR(COUNT));
 		*cs++ = lower_32_bits(vma->node.start + 1000 * sizeof(*cs));
 		*cs++ = upper_32_bits(vma->node.start + 1000 * sizeof(*cs));
+	}
 
 	*cs++ = MI_BATCH_BUFFER_START_GEN8;
 	*cs++ = lower_32_bits(vma->node.start + loop * sizeof(*cs));
@@ -103,7 +106,7 @@ create_spin_counter(struct intel_engine_cs *engine,
 	i915_gem_object_flush_map(obj);
 
 	*cancel = base + loop;
-	*counter = memset32(base + 1000, 0, 1);
+	*counter = srm ? memset32(base + 1000, 0, 1) : NULL;
 	return vma;
 }
 
@@ -317,12 +320,152 @@ static u64 measure_frequency_at(struct intel_rps *rps, u32 *cntr, int *freq)
 	return div_u64(x[1] + 2 * x[2] + x[3], 4);
 }
 
+static u64 __measure_cs_frequency(struct intel_engine_cs *engine,
+				  int duration_ms)
+{
+	u64 dc, dt;
+
+	dt = ktime_get();
+	dc = intel_uncore_read_fw(engine->uncore, CS_GPR(0));
+	usleep_range(1000 * duration_ms, 2000 * duration_ms);
+	dc = intel_uncore_read_fw(engine->uncore, CS_GPR(0)) - dc;
+	dt = ktime_get() - dt;
+
+	return div64_u64(1000 * 1000 * dc, dt);
+}
+
+static u64 measure_cs_frequency_at(struct intel_rps *rps,
+				   struct intel_engine_cs *engine,
+				   int *freq)
+{
+	u64 x[5];
+	int i;
+
+	*freq = rps_set_check(rps, *freq);
+	for (i = 0; i < 5; i++)
+		x[i] = __measure_cs_frequency(engine, 2);
+	*freq = (*freq + read_cagf(rps)) / 2;
+
+	/* A simple triangle filter for better result stability */
+	sort(x, 5, sizeof(*x), cmp_u64, NULL);
+	return div_u64(x[1] + 2 * x[2] + x[3], 4);
+}
+
 static bool scaled_within(u64 x, u64 y, u32 f_n, u32 f_d)
 {
 	return f_d * x > f_n * y && f_n * x < f_d * y;
 }
 
-int live_rps_frequency(void *arg)
+int live_rps_frequency_cs(void *arg)
+{
+	void (*saved_work)(struct work_struct *wrk);
+	struct intel_gt *gt = arg;
+	struct intel_rps *rps = &gt->rps;
+	struct intel_engine_cs *engine;
+	enum intel_engine_id id;
+	int err = 0;
+
+	/*
+	 * The premise is that the GPU does change freqency at our behest.
+	 * Let's check there is a correspondence between the requested
+	 * frequency, the actual frequency, and the observed clock rate.
+	 */
+
+	if (!rps->enabled || rps->max_freq <= rps->min_freq)
+		return 0;
+
+	if (INTEL_GEN(gt->i915) < 8) /* for CS simplicity */
+		return 0;
+
+	intel_gt_pm_wait_for_idle(gt);
+	saved_work = rps->work.func;
+	rps->work.func = dummy_rps_work;
+
+	for_each_engine(engine, gt, id) {
+		struct i915_request *rq;
+		struct i915_vma *vma;
+		u32 *cancel, *cntr;
+		struct {
+			u64 count;
+			int freq;
+		} min, max;
+
+		vma = create_spin_counter(engine,
+					  engine->kernel_context->vm, false,
+					  &cancel, &cntr);
+		if (IS_ERR(vma)) {
+			err = PTR_ERR(vma);
+			break;
+		}
+
+		rq = intel_engine_create_kernel_request(engine);
+		if (IS_ERR(rq)) {
+			err = PTR_ERR(rq);
+			goto err_vma;
+		}
+
+		i915_vma_lock(vma);
+		err = i915_request_await_object(rq, vma->obj, false);
+		if (!err)
+			err = i915_vma_move_to_active(vma, rq, 0);
+		if (!err)
+			err = rq->engine->emit_bb_start(rq,
+							vma->node.start,
+							PAGE_SIZE, 0);
+		i915_vma_unlock(vma);
+		i915_request_add(rq);
+		if (err)
+			goto err_vma;
+
+		if (wait_for(intel_uncore_read(engine->uncore, CS_GPR(0)),
+			     10)) {
+			pr_err("%s: timed loop did not start\n",
+			       engine->name);
+			goto err_vma;
+		}
+
+		min.freq = rps->min_freq;
+		min.count = measure_cs_frequency_at(rps, engine, &min.freq);
+
+		max.freq = rps->max_freq;
+		max.count = measure_cs_frequency_at(rps, engine, &max.freq);
+
+		pr_info("%s: min:%lluKHz @ %uMHz, max:%lluKHz @ %uMHz [%d%%]\n",
+			engine->name,
+			min.count, intel_gpu_freq(rps, min.freq),
+			max.count, intel_gpu_freq(rps, max.freq),
+			(int)DIV64_U64_ROUND_CLOSEST(100 * min.freq * max.count,
+						     max.freq * min.count));
+
+		if (!scaled_within(max.freq * min.count,
+				   min.freq * max.count,
+				   2, 3)) {
+			pr_err("%s: CS did not scale with frequency! scaled min:%llu, max:%llu\n",
+			       engine->name,
+			       max.freq * min.count,
+			       min.freq * max.count);
+			err = -EINVAL;
+		}
+
+err_vma:
+		*cancel = MI_BATCH_BUFFER_END;
+		i915_gem_object_unpin_map(vma->obj);
+		i915_vma_unpin(vma);
+		i915_vma_put(vma);
+
+		if (igt_flush_test(gt->i915))
+			err = -EIO;
+		if (err)
+			break;
+	}
+
+	intel_gt_pm_wait_for_idle(gt);
+	rps->work.func = saved_work;
+
+	return err;
+}
+
+int live_rps_frequency_srm(void *arg)
 {
 	void (*saved_work)(struct work_struct *wrk);
 	struct intel_gt *gt = arg;
@@ -357,7 +500,7 @@ int live_rps_frequency(void *arg)
 		} min, max;
 
 		vma = create_spin_counter(engine,
-					  engine->kernel_context->vm,
+					  engine->kernel_context->vm, true,
 					  &cancel, &cntr);
 		if (IS_ERR(vma)) {
 			err = PTR_ERR(vma);

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

@@ -7,7 +7,8 @@
 #define SELFTEST_RPS_H
 
 int live_rps_control(void *arg);
-int live_rps_frequency(void *arg);
+int live_rps_frequency_cs(void *arg);
+int live_rps_frequency_srm(void *arg);
 int live_rps_interrupt(void *arg);
 int live_rps_power(void *arg);