From c344e60c9adaf3b744940a501fab099250f6075b Mon Sep 17 00:00:00 2001
From: "Enrico Weigelt, metux IT consult" <info@metux.net>
Date: Thu, 22 Jan 2026 13:16:25 +0100
Subject: [PATCH] fix rounding on result of SiSCalcVRate()

Signed-off-by: Enrico Weigelt, metux IT consult <info@metux.net>
---
 src/sis_driver.c  | 6 ++++--
 src/sis_utility.c | 8 +++++---
 src/sis_vga.c     | 4 +++-
 3 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/src/sis_driver.c b/src/sis_driver.c
index db21afc..a1c657b 100644
--- a/src/sis_driver.c
+++ b/src/sis_driver.c
@@ -44,6 +44,8 @@
  */
 #include "config.h"
 
+#include <math.h>
+
 #include "sis.h"
 
 #include "extinit.h"
@@ -1148,7 +1150,7 @@ SiSCopyModeNLink(ScrnInfoPtr pScrn, DisplayModePtr dest,
      * simply set this to the refresh rate for the CRT1 mode (since CRT2 will
      * mostly be LCD or TV anyway).
      */
-    mode->VRefresh = SiSCalcVRate(i);
+    mode->VRefresh = roundf(SiSCalcVRate(i));
 
     if( ((mode->HDisplay * ((pScrn->bitsPerPixel + 7) / 8) * mode->VDisplay) > pSiS->maxxfbmem) ||
 	(mode->HDisplay > 4088) ||
@@ -13102,7 +13104,7 @@ SISSearchCRT1Rate(ScrnInfoPtr pScrn, DisplayModePtr mode)
 
    defindex = (xres == 800 || xres == 1024 || xres == 1280) ? 0x02 : 0x01;
 
-   irefresh = (int)SiSCalcVRate(mode);
+   irefresh = roundf(SiSCalcVRate(mode));
    if(!irefresh) return defindex;
 
    /* SiS730 has troubles on CRT2 if CRT1 is at 32bpp */
diff --git a/src/sis_utility.c b/src/sis_utility.c
index ca8d98c..98efe6d 100644
--- a/src/sis_utility.c
+++ b/src/sis_utility.c
@@ -30,8 +30,10 @@
  */
 #include "config.h"
 
-#include "sis.h"
+#include <math.h>
 #include <X11/X.h>
+
+#include "sis.h"
 #include "dixstruct.h"
 
 #include "sis_videostr.h"
@@ -784,12 +786,12 @@ SISGetMergedModeDetails(ScrnInfoPtr pScrn,
     tmode = ((SiSMergedDisplayModePtr)mode->Private)->CRT1;
     *crt1x = tmode->HDisplay;
     *crt1y = tmode->VDisplay;
-    *crt1clk = (unsigned int)SiSCalcVRate(tmode);
+    *crt1clk = roundf(SiSCalcVRate(tmode));
 
     tmode = ((SiSMergedDisplayModePtr)mode->Private)->CRT2;
     *crt2x = tmode->HDisplay;
     *crt2y = tmode->VDisplay;
-    *crt2clk = (unsigned int)SiSCalcVRate(tmode);
+    *crt2clk = roundf(SiSCalcVRate(tmode));
 }
 
 /***********************************
diff --git a/src/sis_vga.c b/src/sis_vga.c
index dc6cd22..eb39935 100644
--- a/src/sis_vga.c
+++ b/src/sis_vga.c
@@ -35,6 +35,8 @@
  */
 #include "config.h"
 
+#include <math.h>
+
 #include "sis.h"
 #define SIS_NEED_inSISREG
 #define SIS_NEED_outSISREG
@@ -179,7 +181,7 @@ SISInit(ScrnInfoPtr pScrn, DisplayModePtr mode)
     int          clock = mode->Clock;
     int          width = mode->HDisplay;
     int          height = mode->VDisplay;
-    int          rate = (int)SiSCalcVRate(mode);
+    int          rate = roundf(SiSCalcVRate(mode));
     int          buswidth = pSiS->BusWidth;
     unsigned int vclk[5];
     UShort       CRT_CPUthresholdLow, CRT_CPUthresholdHigh, CRT_ENGthreshold;