I am using Qt as a gui rendering to fb0. At the same time, I am rendering OpenGL via the GPU (not using Qt) to fb1. I modify the alpha value of the foreground/background to blend the two. It all works fine out the hdmi port in terms of performance (the opengl is actually video blended with images) and image quality.
Now I need to output the same thing out the lcd interface, but in YCrCb (YUV16) not RGB. The GPU can only render RGB, so somehow the IC needs to do the colorspace transforms.
I have tried various settings of video=lcd:1280x720@60M,fbpix=<f>,if=<i> (where <f> has been YUV444, RGB245, RGB16, etc and similarly <i> has been various formats. No combination seems to work. It's always lots of green and pink - which I think means the display is treating RGB pixels as if they were in fact YUV.