lib/igt_kms: Reset FIFO underruns on first commit after init()/reset().

When we set the test to its first state, we will clear FIFO underrun
status through the debugfs, so that any underruns caused by the tests
will not affect other tests. In particular this also resets the FBC
FIFO underrun status, so previous failures won't affect other tests
that depend on FBC.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=105681
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/lib/igt_kms.c b/lib/igt_kms.c
index 4b25f836..35c77da7 100644
--- a/lib/igt_kms.c
+++ b/lib/igt_kms.c
@@ -3115,6 +3115,13 @@ display_commit_changed(igt_display_t *display, enum igt_commit_style s)
 	}
 
 	if (display->first_commit) {
+		int fd = igt_debugfs_open(display->drm_fd, "i915_fifo_underrun_reset", O_WRONLY);
+		if (fd >= 0) {
+			igt_assert_eq(write(fd, "y", 1), 1);
+
+			close(fd);
+		}
+
 		igt_display_drop_events(display);
 		display->first_commit = false;
 	}