[Intel-gfx] [PATCH i-g-t] igt/pm_rps: Clear previous high load on high->low transition

[Chris Wilson]

Make sure we do flush out the previous spinner and delay signaling
transition completion until we do.

References: https://bugs.freedesktop.org/show_bug.cgi?id=102250
Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Katarzyna Dec <katarzyna.dec at intel.com>
---
 tests/pm_rps.c | 26 +++++++++++++++++++++-----
 1 file changed, 21 insertions(+), 5 deletions(-)

diff --git a/tests/pm_rps.c b/tests/pm_rps.c
index 84e71fa8a..23b33f41b 100644
--- a/tests/pm_rps.c
+++ b/tests/pm_rps.c
@@ -218,6 +218,7 @@ static void load_helper_set_load(enum load load)
 
 static void load_helper_run(enum load load)
 {
+	bool dummy;
 	int link[2];
 
 	/*
@@ -233,13 +234,14 @@ static void load_helper_run(enum load load)
 
 	lh.exit = false;
 	lh.load = load;
-	lh.signal = false;
+	lh.signal = true;
 
 	pipe(link);
 	lh.link = link[1];
 
 	igt_fork_helper(&lh.igt_proc) {
 		igt_spin_t *spin[2] = {};
+		bool prev_load;
 		uint32_t handle;
 
 		signal(SIGUSR1, load_helper_signal_handler);
@@ -247,10 +249,14 @@ static void load_helper_run(enum load load)
 
 		igt_debug("Applying %s load...\n", lh.load ? "high" : "low");
 
+		prev_load = lh.load == HIGH;
 		spin[0] = __igt_spin_batch_new(drm_fd);
-		if (lh.load == HIGH)
+		if (prev_load)
 			spin[1] = __igt_spin_batch_new(drm_fd);
+		prev_load = !prev_load; /* send the initial signal */
 		while (!lh.exit) {
+			bool high_load;
+
 			handle = spin[0]->handle;
 			igt_spin_batch_end(spin[0]);
 			while (gem_bo_busy(drm_fd, handle))
@@ -259,13 +265,20 @@ static void load_helper_run(enum load load)
 			igt_spin_batch_free(drm_fd, spin[0]);
 			usleep(100);
 
-			spin[0] = spin[1];
-			spin[lh.load == HIGH] = __igt_spin_batch_new(drm_fd);
+			high_load = lh.load == HIGH;
+			if (!high_load && spin[1]) {
+				igt_spin_batch_free(drm_fd, spin[1]);
+				spin[1] = NULL;
+			} else {
+				spin[0] = spin[1];
+			}
+			spin[high_load] = __igt_spin_batch_new(drm_fd);
 
-			if (lh.signal) {
+			if (lh.signal && high_load != prev_load) {
 				write(lh.link, &lh.signal, sizeof(lh.signal));
 				lh.signal = false;
 			}
+			prev_load = high_load;
 		}
 
 		handle = spin[0]->handle;
@@ -294,6 +307,9 @@ static void load_helper_run(enum load load)
 
 	close(lh.link);
 	lh.link = link[0];
+
+	/* wait for our helper to complete its first round */
+	igt_assert_eq(read(lh.link, &dummy, sizeof(dummy)), sizeof(dummy));
 }
 
 static void load_helper_stop(void)
-- 
2.19.0.rc1