[igt-dev] [PATCH V4 i-g-t] Skip VBlank tests in modules without VBlank

[Rodrigo Siqueira]

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).

Changes since V3:
 Daniel Vetter:
  - Add documentation for kms_vblank_status()

Changes since V2:
 - Add new branch coverage to check if VBlank is enabled or not
 - Update commit message
 - Change function name from kms_has_vblank to kms_vblank_status

Changes since 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()

Signed-off-by: Rodrigo Siqueira <rodrigosiqueiramelo at gmail.com>
---
 lib/igt_kms.c    | 20 ++++++++++++++++++++
 lib/igt_kms.h    |  2 ++
 tests/kms_flip.c | 27 +++++++++++++++++++++++++--
 3 files changed, 47 insertions(+), 2 deletions(-)

diff --git a/lib/igt_kms.c b/lib/igt_kms.c
index 85a911e1..81fbafe0 100644
--- a/lib/igt_kms.c
+++ b/lib/igt_kms.c
@@ -1654,6 +1654,26 @@ void igt_assert_plane_visible(int fd, enum pipe pipe, bool visibility)
 	igt_assert_eq(visible, visibility);
 }
 
+/**
+ * kms_vblank_status:
+ * @fd: DRM fd
+ *
+ * Get the VBlank status after an attempt to call drmWaitVBlank(). This
+ * function is useful for checking if a driver has support or not for VBlank.
+ *
+ * Returns: The errno code generated by drmWaitVBlank()
+ */
+int kms_vblank_status(int fd)
+{
+	drmVBlank dummy_vbl;
+
+	memset(&dummy_vbl, 0, sizeof(drmVBlank));
+	dummy_vbl.request.type = DRM_VBLANK_ABSOLUTE;
+
+	drmWaitVBlank(fd, &dummy_vbl);
+	return errno;
+}
+
 /*
  * A small modeset API
  */
diff --git a/lib/igt_kms.h b/lib/igt_kms.h
index 679d4e84..259eaa75 100644
--- a/lib/igt_kms.h
+++ b/lib/igt_kms.h
@@ -230,6 +230,8 @@ void kmstest_wait_for_pageflip(int fd);
 unsigned int kmstest_get_vblank(int fd, int pipe, unsigned int flags);
 void igt_assert_plane_visible(int fd, enum pipe pipe, bool visibility);
 
+int kms_vblank_status(int fd);
+
 /*
  * A small modeset API
  */
diff --git a/tests/kms_flip.c b/tests/kms_flip.c
index 798fc4e8..efc59328 100755
--- a/tests/kms_flip.c
+++ b/tests/kms_flip.c
@@ -73,6 +73,7 @@
 #define TEST_TS_CONT		(1 << 27)
 #define TEST_BO_TOOBIG		(1 << 28)
 
+#define TEST_NO_VBLANK		(1 << 29)
 #define TEST_BASIC		(1 << 30)
 
 #define EVENT_FLIP		(1 << 0)
@@ -125,6 +126,18 @@ struct event_state {
 	int seq_step;
 };
 
+static bool vblank_dependence(int flags)
+{
+	int vblank_flags = TEST_VBLANK | TEST_VBLANK_BLOCK |
+			   TEST_VBLANK_ABSOLUTE | TEST_VBLANK_EXPIRED_SEQ |
+			   TEST_TS_CONT | TEST_CHECK_TS | TEST_VBLANK_RACE;
+
+	if (flags & vblank_flags)
+		return true;
+
+	return false;
+}
+
 static float timeval_float(const struct timeval *tv)
 {
 	return tv->tv_sec + tv->tv_usec / 1000000.0f;
@@ -493,11 +506,11 @@ static void check_state(const struct test_output *o, const struct event_state *e
 	/* check only valid if no modeset happens in between, that increments by
 	 * (1 << 23) on each step. This bounding matches the one in
 	 * DRM_IOCTL_WAIT_VBLANK. */
-	if (!(o->flags & (TEST_DPMS | TEST_MODESET)))
+	if (!(o->flags & (TEST_DPMS | TEST_MODESET | TEST_NO_VBLANK))) {
 		igt_assert_f(es->current_seq - (es->last_seq + o->seq_step) <= 1UL << 23,
 			     "unexpected %s seq %u, should be >= %u\n",
 			     es->name, es->current_seq, es->last_seq + o->seq_step);
-
+	}
 	/* Check that the vblank frame didn't wrap unexpectedly. */
 	if (o->flags & TEST_TS_CONT) {
 		/* Ignore seq_step here since vblank waits time out immediately
@@ -1184,6 +1197,7 @@ static void run_test_on_crtc_set(struct test_output *o, int *crtc_idxs,
 	unsigned bo_size = 0;
 	uint64_t tiling;
 	int i;
+	int vblank_status = 0;
 
 	switch (crtc_count) {
 	case 1:
@@ -1267,6 +1281,15 @@ static void run_test_on_crtc_set(struct test_output *o, int *crtc_idxs,
 	}
 	igt_assert(fb_is_bound(o, o->fb_ids[0]));
 
+	vblank_status = kms_vblank_status(drm_fd);
+	if (vblank_status == EOPNOTSUPP) {
+		if (vblank_dependence(o->flags))
+			igt_require_f(!(vblank_status == EOPNOTSUPP),
+				      "Vblank: %s\n", strerror(vblank_status));
+		else
+			o->flags |= TEST_NO_VBLANK;
+	}
+
 	/* quiescent the hw a bit so ensure we don't miss a single frame */
 	if (o->flags & TEST_CHECK_TS)
 		calibrate_ts(o, crtc_idxs[0]);
-- 
2.20.1
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