[Intel-gfx] [PATCH igt 2/2] igt/perf_pmu: Replace hard-coded sleep before rc6 with a probe

[Chris Wilson]

Instead of trying to sleep for 2 evaluations intervals and then assuming
that rc6 is working, poll the rc6 residency instead.

References: https://bugs.freedesktop.org/show_bug.cgi?id=103929
Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
---
 tests/perf_pmu.c | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/tests/perf_pmu.c b/tests/perf_pmu.c
index e872f4e55..65bc734da 100644
--- a/tests/perf_pmu.c
+++ b/tests/perf_pmu.c
@@ -1008,6 +1008,20 @@ static unsigned long rc6_enable_us(void)
 	return 2 * 160 * 1000;
 }
 
+static bool wait_for_rc6(int fd)
+{
+	struct timespec tv = {};
+	uint64_t start, now;
+
+	start = pmu_read_single(fd);
+	do {
+		usleep(50);
+		now = pmu_read_single(fd);
+	} while (start == now && !igt_seconds_elapsed(&tv));
+
+	return start != now;
+}
+
 static void
 test_rc6(int gem_fd)
 {
@@ -1019,7 +1033,7 @@ test_rc6(int gem_fd)
 	fd = open_pmu(I915_PMU_RC6_RESIDENCY);
 
 	gem_quiescent_gpu(gem_fd);
-	usleep(rc6_enable_us()); /* wait for the rc6 cycle counter to kick in */
+	igt_require(wait_for_rc6(fd));
 
 	/* Go idle and check full RC6. */
 	prev = pmu_read_single(fd);
-- 
2.15.1