[Intel-gfx] [PATCH i-g-t] perf: Verify rc6 works first

[Chris Wilson]

We want to verify that OA disables rc6 (so that its metrics are not
interrupted by the device sleeping), and once OA is finished, the device
is allowed to sleep again. If rc6 is broken, the test fails since rc6
never recovers -- but that is expected as rc6 is broken.

Skip the test rather than fail for an external issue; we know rc6 is
broken on ehl!

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
---
 tests/perf.c | 28 ++++++++++++++++++----------
 1 file changed, 18 insertions(+), 10 deletions(-)

diff --git a/tests/perf.c b/tests/perf.c
index b7d5e50e3..24d245496 100644
--- a/tests/perf.c
+++ b/tests/perf.c
@@ -4147,27 +4147,35 @@ test_rc6_disable(void)
 		.num_properties = sizeof(properties) / 16,
 		.properties_ptr = to_user_pointer(properties),
 	};
-	unsigned long n_events_start, n_events_end;
-	unsigned long rc6_enabled;
+	unsigned long rc6_start, rc6_end, rc6_enabled;
 
 	rc6_enabled = 0;
 	igt_sysfs_scanf(sysfs, "power/rc6_enable", "%lu", &rc6_enabled);
 	igt_require(rc6_enabled);
 
+	/* Verify rc6 is functional by measuring residency while idle */
+	gem_quiescent_gpu(drm_fd);
+	rc6_start = rc6_residency_ms();
+	usleep(50000);
+	rc6_end = rc6_residency_ms();
+	igt_require(rc6_end != rc6_start);
+
+	/* While OA is active, we keep rc6 disabled so we don't lose metrics */
 	stream_fd = __perf_open(drm_fd, &param, false);
 
-	n_events_start = rc6_residency_ms();
-	nanosleep(&(struct timespec){ .tv_sec = 0, .tv_nsec = 500000000 }, NULL);
-	n_events_end = rc6_residency_ms();
-	igt_assert_eq(n_events_end - n_events_start, 0);
+	rc6_start = rc6_residency_ms();
+	usleep(50000);
+	rc6_end = rc6_residency_ms();
+	igt_assert_eq(rc6_end - rc6_start, 0);
 
 	__perf_close(stream_fd);
 	gem_quiescent_gpu(drm_fd);
 
-	n_events_start = rc6_residency_ms();
-	nanosleep(&(struct timespec){ .tv_sec = 1, .tv_nsec = 0 }, NULL);
-	n_events_end = rc6_residency_ms();
-	igt_assert_neq(n_events_end - n_events_start, 0);
+	/* But once OA is closed, we expect the device to sleep again */
+	rc6_start = rc6_residency_ms();
+	usleep(50000);
+	rc6_end = rc6_residency_ms();
+	igt_assert_neq(rc6_end - rc6_start, 0);
 }
 
 static void
-- 
2.26.2