[Intel-gfx] [PATCH i-g-t] kms_flip: Calculate max acceptable delta for TEST_TS_CONT

[Tomeu Vizoso]

Right now it's hardcoded to a maximum difference of 150 page flips to
account the fixed amount of time that the suspend cycle should take, but
in some cases suspending and resuming will take much more time due to
unrelated issues.

In my case, I have a machine in which the RTC will cause an interrupt
storm (~8k interrupts per second) from the moment an alarm is set until
the alarm actually fires. This causes so much CPU contention that the
suspend cycle takes much longer and the 150 value is not enough.

This patch takes into account the time that passed between the last two
page flips and calculates an acceptable difference taking into account
the vertical refresh rate of the current mode.

Signed-off-by: Tomeu Vizoso <tomeu.vizoso at collabora.com>
References: https://bugs.freedesktop.org/show_bug.cgi?id=98289
---
 tests/kms_flip.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/tests/kms_flip.c b/tests/kms_flip.c
index 41406dfe9199..522777c24da2 100644
--- a/tests/kms_flip.c
+++ b/tests/kms_flip.c
@@ -500,17 +500,25 @@ static void check_state(const struct test_output *o, const struct event_state *e
 
 	/* Check that the vblank frame didn't wrap unexpectedly. */
 	if (o->flags & TEST_TS_CONT) {
+		double elapsed;
+		unsigned max_delta;
+
 		/* Ignore seq_step here since vblank waits time out immediately
 		 * when we kill the crtc. */
 		igt_assert_f(es->current_seq - es->last_seq >= 0,
 			     "unexpected %s seq %u, should be >= %u\n",
 			     es->name, es->current_seq, es->last_seq);
-		igt_assert_f(es->current_seq - es->last_seq <= 150,
+
+		timersub(&es->current_ts, &es->last_ts, &diff);
+		elapsed = 1e6*diff.tv_sec + diff.tv_usec;
+		max_delta = elapsed * o->kmode[0].vrefresh / 1e6;
+
+		igt_assert_f(es->current_seq - es->last_seq <= max_delta,
 			     "unexpected %s seq %u, should be < %u\n",
-			     es->name, es->current_seq, es->last_seq + 150);
+			     es->name, es->current_seq, es->last_seq + max_delta);
 
-		igt_debug("testing ts continuity: Current frame %u, old frame %u\n",
-			  es->current_seq, es->last_seq);
+		igt_debug("testing ts continuity: Current frame %u, old frame %u, max delta %u\n",
+			  es->current_seq, es->last_seq, max_delta);
 	}
 
 	if (o->flags & TEST_CHECK_TS) {
-- 
2.9.3