Working on getting cloning to work on a laptop, and realized that laptop panel's only provides a single resolution. At least with Intel, these usually have a panel fitter that allows you to set the CRTC to any resolution, and the panel fitter scales for you.
We also figured out that you can use DRM_MODE_SCALE_FULLSCREEN with drmModeConnectorSetProperty and the "scaling mode" property to tell the panel fitter how you want it to scale.
The problem that I have is, how exactly should we fill in the modeInfo structure. Right now, we have gotten it to work on all of our test equipment (two laptops) by just taking the preferred mode, and changing it's vdisplay and hdisplay to the resolution that we want. The rest of the settings are left unchanged, which in my mind makes no sense.
One option that I was thinking of was to take the mode from the other monitor that is not being scaled. Most of the settings in the modeInfo struct should be good, except I noticed in testing that the flags field is different between the panel and a VGA monitor (and I really have no idea what the flags field should be set to).
I also noticed that there is a DRM_MODE_TYPE_USERDEF type, and it would make sense to me that the type should be changed to this since I am defining it in software, but I'm not sure if it is actually used.
At any rate, do any of you have any insight on the proper way to fill out this modeInfo struct when using the panel fitter and a user defined mode?
Thanks a ton, - Rian