[Intel-gfx] [PATCH v3] drm/i915/selftests: Wait for the dma-fence timeout

[Chris Wilson]

When testing that the timeout fired, we need to be sure we have waited
just long enough for the timeout to have occurred and for the softirq
(on another cpu) to have completed. Sleeping for an arbitrary amount is
prone to error, so wait for the timeout instead and complain if it was
too late.

v2: Use wait_event_timeout to provide an upper bound
v3: Fix inverted check for wait_event_timeout timing out

References: https://bugs.freedesktop.org/show_bug.cgi?id=104670
Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
---
 drivers/gpu/drm/i915/selftests/i915_sw_fence.c | 27 +++++---------------------
 1 file changed, 5 insertions(+), 22 deletions(-)

diff --git a/drivers/gpu/drm/i915/selftests/i915_sw_fence.c b/drivers/gpu/drm/i915/selftests/i915_sw_fence.c
index 4fb51deb81a1..d75eb97819c1 100644
--- a/drivers/gpu/drm/i915/selftests/i915_sw_fence.c
+++ b/drivers/gpu/drm/i915/selftests/i915_sw_fence.c
@@ -661,7 +661,6 @@ static int test_dma_fence(void *arg)
 {
 	struct i915_sw_fence *timeout = NULL, *not = NULL;
 	unsigned long delay = i915_selftest.timeout_jiffies;
-	unsigned long end, sleep;
 	struct dma_fence *dma;
 	int err;
 
@@ -688,36 +687,20 @@ static int test_dma_fence(void *arg)
 	}
 
 	/* We round the timeout for the fence up to the next second */
-	end = round_jiffies_up(jiffies + delay);
+	delay = round_jiffies_up_relative(delay);
 
-	sleep = jiffies_to_usecs(delay) / 3;
-	usleep_range(sleep, 2 * sleep);
-	if (time_after(jiffies, end)) {
-		pr_debug("Slept too long, delay=%lu, skipping!\n", delay);
-		goto skip;
-	}
-
-	if (i915_sw_fence_done(timeout) || i915_sw_fence_done(not)) {
-		pr_err("Fences signaled too early\n");
+	if (!wait_event_timeout(timeout->wait,
+				i915_sw_fence_done(timeout),
+				2 * delay)) {
+		pr_err("Timeout fence unsignaled!\n");
 		goto err;
 	}
 
-	do {
-		sleep = jiffies_to_usecs(end - jiffies + 1);
-		usleep_range(sleep, 2 * sleep);
-	} while (!time_after(jiffies, end));
-
 	if (i915_sw_fence_done(not)) {
 		pr_err("No timeout fence signaled!\n");
 		goto err;
 	}
 
-	if (!i915_sw_fence_done(timeout)) {
-		pr_err("Timeout fence unsignaled!\n");
-		goto err;
-	}
-
-skip:
 	dma_fence_signal(dma);
 
 	if (!i915_sw_fence_done(timeout) || !i915_sw_fence_done(not)) {
-- 
2.15.1