Still waiting to get a fix so I can get video out at 4k on my RK1s on a 2.4 board. Any ideas when thats coming? Its been on the radar for months now.

We were working on identifying if TPi2 v2.4 can work with a 4K output and the answer is it might, but it depends also on a cable and the screen. We actually made changed on v2.5.2 that's going to be released shortly to address this and it'll support 4K output.

I have had this working, but the requirements are pretty specific. You need a display that can do 4K at 30hz (I think it’s HDMI 1.3), and ensure your HDMI cable is capable of handling the bandwidth.