builtin display using amdgpu gives a black screen on macbook pro 13, 3

[D Marinus]

Hi!

Since I've updated the linux kernel to 5.6 my builtin display of my
Apple Macbook Pro 13,3 is blank. The following bug reports have been
opened:

https://github.com/Dunedan/mbp-2016-linux/issues/142
https://bugzilla.kernel.org/show_bug.cgi?id=207589
https://bugzilla.redhat.com/show_bug.cgi?id=1829174


xrandr gives the following message
xrandr: Output eDP is not disconnected but has no modes

the /sys/kernel/debug/vgaswitcheroo/switch entry is missing

lspci gives:
01:00.0 VGA compatible controller: Advanced Micro Devices, Inc.
[AMD/ATI] Baffin [Radeon RX 460/560D / Pro
450/455/460/555/555X/560/560X] (rev ef)

Any thoughts on the cause or fix? What would be helpful information?

Thanks a lot!