I connect the rockpi 4 to a Samsung display whose normal resolution is 1680x1050 via a hdmi to dvi line, but the maxium resolution I can choose is 1280x1024. 

And when I connect it to a 4K tv via hdmi, the maxium resolution is 1920x1080, not 3840x2160.

The legacy kernel (4.4.210) works perfectly in both cases.

Probably not supported yet.   Try - Chromium > chrome://gpu

 

I get

Quote

Graphics Feature Status

Canvas: Software only, hardware acceleration unavailable

Flash: Unavailable

Flash Stage3D: Unavailable

Flash Stage3D Baseline profile: Unavailable

Compositing: Unavailable

Multiple Raster Threads: Force enabled

Out-of-process Rasterization: Unavailable

Hardware Protected Video Decode: Unavailable

Rasterization: Hardware accelerated

Skia Renderer: Disabled

Video Decode: Unavailable

Viz Display Compositor: Enabled

Viz Hit-test Surface Layer: Enabled

Vulkan: Disabled

WebGL: Hardware accelerated but at reduced performance

WebGL2: Unavailable

 

On 1/25/2020 at 9:59 AM, hallo1 said:

The legacy kernel (4.4.210) works perfectly in both cases.

In about a year (or more) most/all features will come to the modern kernel and (hopefully) work perfectly. Which is why we provide both kernels. 

can you provide an the output of sudo armbianmonitor -u? I don't have a recent current nor dev image installed on my RockPi.

Output is here: http://ix.io/28uM

Sadly, my board's HDMI output have been damanged by static electricity when I get the output. Probably it will cause wrong information.

I tried out my Rock Pi 4B with a custom-built 5.8.0-rc6 kernel based on @balbes150 armbian-build fork, and despite my monitor supporting a resolution of 1920x1200, the maximum I could select was 1920x1080.

http://ix.io/2siM

Once I've tried the official Armbian images and balbes150's own build, I'm going to edit this post/reply again with whether any of them fix this problem.