[PATCH libdrm] modetest: Fix mode_vrefresh() for interlace/dblscan/vscan

[Geert Uytterhoeven]

mode_vrefresh() does not take into account interlaced, doublescan, and
multiscan modes, leading to incorrect refresh rates.

Fix this, based on drm_mode_vrefresh() in Linux.

Signed-off-by: Geert Uytterhoeven <geert at linux-m68k.org>
---
 tests/modetest/modetest.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/tests/modetest/modetest.c b/tests/modetest/modetest.c
index 8ff6c80da8ba6db6..9ceb5688f7683ffc 100644
--- a/tests/modetest/modetest.c
+++ b/tests/modetest/modetest.c
@@ -137,8 +137,19 @@ static inline int64_t U642I64(uint64_t val)
 
 static float mode_vrefresh(drmModeModeInfo *mode)
 {
-	return  mode->clock * 1000.00
-			/ (mode->htotal * mode->vtotal);
+	unsigned int num, den;
+
+	num = mode->clock;
+	den = mode->htotal * mode->vtotal;
+
+	if (mode->flags & DRM_MODE_FLAG_INTERLACE)
+		num *= 2;
+	if (mode->flags & DRM_MODE_FLAG_DBLSCAN)
+		den *= 2;
+	if (mode->vscan > 1)
+		den *= mode->vscan;
+
+	return num * 1000.00 / den;
 }
 
 #define bit_name_fn(res)					\
-- 
2.25.1