[PATCH] winex11.drv: Fix incorrect frequency for doublescan and interlaced modes.

[Zhiyi Zhang]

Signed-off-by: Zhiyi Zhang 
---
 dlls/winex11.drv/xrandr.c | 23 +++++++++++++++++++++--
 1 file changed, 21 insertions(+), 2 deletions(-)

diff --git a/dlls/winex11.drv/xrandr.c b/dlls/winex11.drv/xrandr.c
index 930e0282be..454f6f2df2 100644
--- a/dlls/winex11.drv/xrandr.c
+++ b/dlls/winex11.drv/xrandr.c
@@ -478,6 +478,26 @@ static XRRCrtcInfo *xrandr12_get_primary_crtc_info( XRRScreenResources *resource
     return NULL;
 }

+static DWORD get_frequency( const XRRModeInfo *mode )
+{
+    if (mode->hTotal && mode->vTotal)
+    {
+        double v_total = mode->vTotal;
+
+        if (mode->modeFlags & RR_DoubleScan)
+            v_total *= 2;
+        if (mode->modeFlags & RR_Interlace)
+            v_total /= 2;
+
+        /* Adding 0.05 instead of 0.5 to round so that common frequencies like
+         * 59.94Hz and 23.976Hz become 59Hz and 24Hz. Using 0.5 would make
+         * 59.94Hz become 60Hz and would make it seem like there are two 60Hz modes */
+        return mode->dotClock / (mode->hTotal * v_total) + 0.05;
+    }
+
+    return 0;
+}
+
 static int xrandr12_init_modes(void)
 {
     unsigned int only_one_resolution = 1, mode_count;
@@ -536,8 +556,7 @@ static int xrandr12_init_modes(void)

if (mode->id == output_info->modes[i])
             {
-                unsigned int dots = mode->hTotal * mode->vTotal;
-                unsigned int refresh = dots ? (mode->dotClock + dots / 2) / dots : 0;
+                unsigned int refresh = get_frequency(mode);

TRACE("Adding mode %#lx: %ux%u@%u.\n", mode->id, mode->width, mode->height, refresh);
                 X11DRV_Settings_AddOneMode( mode->width, mode->height, 0, refresh );

[Dmitry Timoshkov]

Zhiyi Zhang  wrote:
> +static DWORD get_frequency( const XRRModeInfo *mode )
> +{
> - if (mode->hTotal && mode->vTotal)
> - {
> -
>    double v_total = mode->vTotal;
> -
> -
>    if (mode->modeFlags & RR_DoubleScan)
> -
>        v_total *= 2;
> -
>    if (mode->modeFlags & RR_Interlace)
> -
>        v_total /= 2;
> -
> -
>    /* Adding 0.05 instead of 0.5 to round so that common frequencies like
> -
>     * 59.94Hz and 23.976Hz become 59Hz and 24Hz. Using 0.5 would make
> -
>     * 59.94Hz become 60Hz and would make it seem like there are two 60Hz modes */
> -
>    return mode->dotClock / (mode->hTotal * v_total) + 0.05;
> - }
> -
> - return 0;
>
> +}

It seems that floating point (and especially double) is not needed here
to do a proper calculation.

[Zhiyi Zhang]

On 2/4/20 4:27 PM, Dmitry Timoshkov wrote:
> Zhiyi Zhang  wrote:
> > +static DWORD get_frequency( const XRRModeInfo *mode )
> > +{
> > - if (mode->hTotal && mode->vTotal)
> > - {
> > -
> >    double v_total = mode->vTotal;
> > -
> > -
> >    if (mode->modeFlags & RR_DoubleScan)
> > -
> >        v_total *= 2;
> > -
> >    if (mode->modeFlags & RR_Interlace)
> > -
> >        v_total /= 2;
> > -
> > -
> >    /* Adding 0.05 instead of 0.5 to round so that common frequencies like
> > -
> >     * 59.94Hz and 23.976Hz become 59Hz and 24Hz. Using 0.5 would make
> > -
> >     * 59.94Hz become 60Hz and would make it seem like there are two 60Hz modes */
> > -
> >    return mode->dotClock / (mode->hTotal * v_total) + 0.05;
> > - }
> > -
> > - return 0;
> >
> > +}
>
> It seems that floating point (and especially double) is not needed here
> to do a proper calculation.

It's needed. See https://gitlab.freedesktop.org/xorg/app/xrandr/commit/00c795e99fe29ecd56e05e...

[Gabriel Ivăncescu]

On 04/02/2020 10:37, Zhiyi Zhang wrote:
> On 2/4/20 4:27 PM, Dmitry Timoshkov wrote:
> > Zhiyi Zhang  wrote:
> > > +static DWORD get_frequency( const XRRModeInfo *mode )
> > > +{
> > > - if (mode->hTotal && mode->vTotal)
> > > - {
> > > -
> > >    double v_total = mode->vTotal;
> > > -
> > > -
> > >    if (mode->modeFlags & RR_DoubleScan)
> > > -
> > >        v_total *= 2;
> > > -
> > >    if (mode->modeFlags & RR_Interlace)
> > > -
> > >        v_total /= 2;
> > > -
> > > -
> > >    /* Adding 0.05 instead of 0.5 to round so that common frequencies like
> > > -
> > >     * 59.94Hz and 23.976Hz become 59Hz and 24Hz. Using 0.5 would make
> > > -
> > >     * 59.94Hz become 60Hz and would make it seem like there are two 60Hz modes */
> > > -
> > >    return mode->dotClock / (mode->hTotal * v_total) + 0.05;
> > > - }
> > > -
> > > - return 0;
> > >
> > > +}
> >
> > It seems that floating point (and especially double) is not needed here
> > to do a proper calculation.
>
> It's needed. See https://gitlab.freedesktop.org/xorg/app/xrandr/commit/00c795e99fe29ecd56e05e...

I think he meant, can't you just multiply both v_total and 
mode->dotClock by 2 for same effect?

int v_total = mode->vTotal * 2;

...

return mode->dotClock * 2 / (mode->hTotal * v_total);

Admittedly it doesn't handle the 0.05 but that seems somewhat arbitrary.