Adjust the description and constants in the timing check to match each other.
Relax the timing constraint to prevent false positives in vblank interval 
checking.
---
 tests/kms_flip.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/tests/kms_flip.c b/tests/kms_flip.c
index 289335a..53b0b10 100644
--- a/tests/kms_flip.c
+++ b/tests/kms_flip.c
@@ -1206,9 +1206,12 @@ static void calibrate_ts(struct test_output *o, int 
crtc_idx)
        stddev = igt_stats_get_std_deviation(&stats);
 
        igt_info("Expected frametime: %.0fus; measured %.1fus +- %.3fus 
accuracy %.2f%%\n",
-                expected, mean, stddev, 100 * 6 * stddev / mean);
-       igt_assert(6 * stddev / mean < 0.005); /* 99% accuracy within 0.5% */
-
+                expected, mean, stddev, 100 * 3 * stddev / mean);
+       /* 99.7% samples within 0.5% of the mean */
+       igt_assert(3 * stddev / mean < 0.005);
+       /* 84% samples within 0.5% of the expected value.
+        * See comments in check_timings() in kms_setmode.c
+        */
        if (fabs(mean - expected) > 2*stddev) {
                igt_warn("vblank interval differs from modeline! expected 
%.1fus, measured %1.fus +- %.3fus, difference %.1fus (%.1f sigma)\n",
                                expected, mean, stddev,
-- 
2.7.4
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