Hi,
A few remarks...
- LCD panels need to be fed with native resolution. You can slightly change frequencies and blanking but you can't absolutely drive them with a different resolution. Although you will see the LCD has a controller that is a tcon so it's only role is to generate low level LCD driving signals and doesn't do any scaling
- format converters such as the HDMI to mipi converter you're using are just converting the "protocol" so they don't perform any scaling. Even if it's edid reports variable scan frequencies it's just due to laziness of the developer... I bet that if you feed it with 300mhz clock it won't work.
- simple scaler boards don't have a frame buffer so they can scale image but vertical timing will stay the same. If for example you want to drive a panel with a 30 hz vertical frequency likely it won't work as panels usually accept vertical frequencies above 50hz.
- complex scaler boards have frame buffers and can perform scan conversion. The most sophisticated ones even do motion compensation, generating intermediate frames when upconverting say from 30 to 60 hz by analyzing moving portions...
Now, getting back to your issue, probably next week I'll release the full flow so you can modify output resolution. Actually it's also possible that we'll release a version that allows changing resolution at run time but that will come later as it requires run time reconfiguration of the pll as Riccardo mentioned.