Hello! It works already when I modify imx6q-pistachio.dts (my board) and enable mxcfb1 to mxcfb4..
And another trick is the boot argument have to take out "bpp=32" setting...
I think it's due to the FSL apps has some hard code to detect demo board setting but I'm not trace yet, after all, I know what's going on, thanks!