tests/kms_flip: Skip VBlank tests in modules without VBlank

The kms_flip test relies on VBlank support, and this situation may
exclude some virtual drivers to take advantage of this set of tests.
This commit adds a mechanism that checks if a module has VBlank. If the
target module has VBlank support, kms_flip will run all the VBlank
tests; otherwise, the VBlank tests will be skipped. Additionally, this
commit improves the test coverage by checks if the function
drmWaitVBlank() returns EOPNOTSUPP (i.e., no VBlank support).

V7: Skip seq number checking and busy flip if the device doesn't support
vblank

V6: Set errno to zero before call drmWaitVBlank() (Chris Wilson)

V5: Drop the DRM_VBLANK_NEXTONMISS (Chris Wilson)

V4: Replace DRM_VBLANK_ABSOLUTE by DRM_VBLANK_RELATIVE and
DRM_VBLANK_NEXTONMISS

V3: Add documentation (Daniel Vetter)

V2: Add new branch coverage to check if VBlank is enabled or not and
update commit message

V1: Chris Wilson
  - Change function name from igt_there_is_vblank to kms_has_vblank
  - Move vblank function check from igt_aux to igt_kms
  - Utilizes memset in dummy_vbl variable
  - Directly return the result of drmWaitVBlank()

Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Rodrigo Siqueira <rodrigosiqueiramelo@gmail.com>

1 files changed, 21 insertions, 0 deletions

diff --git a/lib/igt_kms.c b/lib/igt_kms.c
index d7d711a7..8a465f67 100644
--- a/lib/igt_kms.c
+++ b/lib/igt_kms.c
@@ -1673,6 +1673,27 @@ void igt_assert_plane_visible(int fd, enum pipe pipe, int plane_index, bool visi
 	igt_assert_eq(visible, visibility);
 }
 
+/**
+ * kms_has_vblank:
+ * @fd: DRM fd
+ *
+ * Get the VBlank errno after an attempt to call drmWaitVBlank(). This
+ * function is useful for checking if a driver has support or not for VBlank.
+ *
+ * Returns: true if target driver has VBlank support, otherwise return false.
+ */
+bool kms_has_vblank(int fd)
+{
+	drmVBlank dummy_vbl;
+
+	memset(&dummy_vbl, 0, sizeof(drmVBlank));
+	dummy_vbl.request.type = DRM_VBLANK_RELATIVE;
+
+	errno = 0;
+	drmWaitVBlank(fd, &dummy_vbl);
+	return (errno != EOPNOTSUPP);
+}
+
 /*
  * A small modeset API
  */