EGLFS (interlaced) modeline cannot be selected

I am trying to setup an modeline for an BlackMagick ATEM, which has an 1080@50i input requirement. Under Xorg, using xrandr this is not a problem, I can set it up, everything works flawlessly even up to a way that I can export the modeline required to get it to work.

Using the tool https://github.com/alanbork/kmsmodeline I was also able to validate that the modeline in fact works. In order to select this modeline I am using an a configuration file. 

{{

{ "device": "/dev/dri/card0", "outputs": [

{ "name": "DVI1", "mode": "74.25 1920 2448 2492 2640 1080 1084 1094 1125 +hsync +vsync interlace" }

]
}}

{{{
qt.qpa.eglfs.kms: "DVI1" mode count: 16 crtc index: 0 crtc id: 50
qt.qpa.eglfs.kms: mode 0 1920 x 1080 @ 60 hz
qt.qpa.eglfs.kms: mode 1 1920 x 1080 @ 60 hz
qt.qpa.eglfs.kms: mode 2 1920 x 1080 @ 60 hz
qt.qpa.eglfs.kms: mode 3 1920 x 1080 @ 60 hz
qt.qpa.eglfs.kms: mode 4 1920 x 1080 @ 50 hz
qt.qpa.eglfs.kms: mode 5 1920 x 1080 @ 50 hz
qt.qpa.eglfs.kms: mode 6 1920 x 1080 @ 30 hz
qt.qpa.eglfs.kms: mode 7 1920 x 1080 @ 30 hz
qt.qpa.eglfs.kms: mode 8 1920 x 1080 @ 25 hz
qt.qpa.eglfs.kms: mode 9 1920 x 1080 @ 24 hz
qt.qpa.eglfs.kms: mode 10 1920 x 1080 @ 24 hz
qt.qpa.eglfs.kms: mode 11 1280 x 720 @ 60 hz
qt.qpa.eglfs.kms: mode 12 1280 x 720 @ 60 hz
qt.qpa.eglfs.kms: mode 13 1280 x 720 @ 50 hz
qt.qpa.eglfs.kms: mode 14 1440 x 576 @ 50 hz
qt.qpa.eglfs.kms: mode 15 1440 x 480 @ 60 hz
qt.qpa.eglfs.kms: Selected mode 16 : 1920 x 1080 @ 0 hz for output "DVI1"
}}

I took the liberty to investigate qkmsdevice.cpp, specifically parseModeline.

{{
static bool parseModeline(const QByteArray &text, drmModeModeInfoPtr mode)
{
char hsync[16];
char vsync[16];
float fclock;

mode->type = DRM_MODE_TYPE_USERDEF;
mode->hskew = 0;
mode->vscan = 0;
mode->vrefresh = 0;
mode->flags = 0;

if (sscanf(text.constData(), "%f %hd %hd %hd %hd %hd %hd %hd %hd %15s %15s",
&fclock,
&mode->hdisplay,
&mode->hsync_start,
&mode->hsync_end,
&mode->htotal,
&mode->vdisplay,
&mode->vsync_start,
&mode->vsync_end,
&mode->vtotal, hsync, vsync) != 11)
return false;

mode->clock = fclock * 1000;

if (strcmp(hsync, "+hsync") == 0)
mode->flags |= DRM_MODE_FLAG_PHSYNC;
else if (strcmp(hsync, "-hsync") == 0)
mode->flags |= DRM_MODE_FLAG_NHSYNC;
else
return false;

if (strcmp(vsync, "+vsync") == 0)
mode->flags |= DRM_MODE_FLAG_PVSYNC;
else if (strcmp(vsync, "-vsync") == 0)
mode->flags |= DRM_MODE_FLAG_NVSYNC;
else
return false;

return true;
}
}}

As can be read from the code above it misses the interlace and dblclk flags. I'll do an attempt to make a patch.