[Intel-gfx] [PATCH igt 2/4] tests/kms_fb_crc: call gem_sync() instead of gem_bo_busy()

[Paulo Zanoni]

From: Paulo Zanoni <paulo.r.zanoni at intel.com>

The way kms_fbc_crc works is that it does an operation that may
trigger/invalidate/update FBC, then it sleeps for 300ms to wait for
FBC to kick in again, then it calls "igt_assert(fbc_enabled())".

This was causing problems where the BLT test would eventually fail in
the fbc_eanbled() assertion.

With the recent FBC move to front buffer rendering tracking, if we
don't call gem_sync() after submitting render and blt commands, it may
take much more than 300ms for FBC to be reenabled:
i915_gem_execbuffer2() indirectly calls intel_fb_obj_invalidate(),
which disables FBC, and then it is only reenabled when
i915_gem_retire_work_handler() happens and indirectly calls
intel_frontbuffer_flush(). Notice that while FBC is not yet enabled,
the screen contents are correct, so this shouldn't really be a "bug".

The gem_sync() call will make sure the long waits don't happen. With
this, 300ms should be much more than enough: either we wait about 50ms
for FBC to be re-enabled - intel_enable_fbc() uses a delayed work - or
it's instantaneous - on the cases where we just do the nuke.

Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
Signed-off-by: Paulo Zanoni <paulo.r.zanoni at intel.com>
---
 tests/kms_fbc_crc.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tests/kms_fbc_crc.c b/tests/kms_fbc_crc.c
index 32c3d98..7c3a412 100644
--- a/tests/kms_fbc_crc.c
+++ b/tests/kms_fbc_crc.c
@@ -122,7 +122,7 @@ static void fill_blt(data_t *data,
 	intel_batchbuffer_flush(batch);
 	intel_batchbuffer_free(batch);
 
-	gem_bo_busy(data->drm_fd, handle);
+	gem_sync(data->drm_fd, handle);
 }
 
 static void scratch_buf_init(struct igt_buf *buf, drm_intel_bo *bo)
@@ -187,7 +187,7 @@ static void fill_render(data_t *data, uint32_t handle,
 
 	intel_batchbuffer_free(batch);
 
-	gem_bo_busy(data->drm_fd, handle);
+	gem_sync(data->drm_fd, handle);
 }
 
 static bool fbc_enabled(data_t *data)
-- 
2.1.3