[igt-dev] [PATCH i-g-t v2 1/2] tests/frontbuffer_tracking: Do not assert FBC state after a page flip changing stride

[José Roberto de Souza]

When the stridechange subtest was introduced f23ea58f1fbb
("kms_frontbuffer_tracking: expand badstride and stridechange")
atomic was not around and change the stride using drmModePageFlip()
was not allowed so it was expected that it would return -EINVAL and
kernel would keep the old framebuffer with the smaller plane that is
know to fit on CFB(if it don't fit the test will skip on the first
full-modeset because "not enough stolen memory" is set).

But after the introduction of atomic the subtest was updated by
f63e070b469d ("kms_frontbuffer_tracking: Fix tests with the new
atomic reality.") to accept a no error return from drmModePageFlip()
but the do_assertions() that follows it was not updated.
As the subtest function comment states, kernel will do fastsets in
this scenario and the allocated CFB could not be enough to keep FBC
enabled over the new framebuffer, so here adding the missing
DONT_ASSERT_FEATURE_STATUS to ignore the FBC state and just test if
CRC match and if kernel do not misbehave.

Other way to solve this issue would be make the kernel do a
full-modeset when CFB is not enough for the new plane so FBC is
disabled with the CRC freeing the actual CFB and then after enable
CRTC again it will try to enable FBC again if it can allocate the
required CFB but by the subtest comment this is not intended.

v2: Assert features when drmModePageFlip() fails aka non-atomic driver(Dhinakaran)

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=105683
Cc: Dhinakaran Pandiyan <dhinakaran.pandiyan at intel.com>
Cc: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
Cc: Paulo Zanoni <paulo.r.zanoni at intel.com>
Signed-off-by: José Roberto de Souza <jose.souza at intel.com>
---
 tests/kms_frontbuffer_tracking.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tests/kms_frontbuffer_tracking.c b/tests/kms_frontbuffer_tracking.c
index 89586326..caef6755 100644
--- a/tests/kms_frontbuffer_tracking.c
+++ b/tests/kms_frontbuffer_tracking.c
@@ -2932,7 +2932,7 @@ static void stridechange_subtest(const struct test_mode *t)
 	 */
 	rc = drmModePageFlip(drm.fd, drm.display.pipes[params->pipe].crtc_id, new_fb->fb_id, 0, NULL);
 	igt_assert(rc == -EINVAL || rc == 0);
-	do_assertions(0);
+	do_assertions(rc ? 0 : DONT_ASSERT_FEATURE_STATUS);
 }
 
 /**
-- 
2.21.0