[bug report]: Black screen in 5.10

[Klaus Kusche]

Hello,

I don't know where and how to report amdgpu bugs 
as the freedesktop.org bugzilla is closed...

My problem:

With kernel 5.10.x, both the internal notebook display and any external screen
become black (or go to the "off" state?) when the kernel boots
(one or two seconds after the VGA text console is shown), 
and the system no longer reacts.

5.9.x is fine.

This seems to happen as soon as the amdgpu kernel driver loads/initializes,
even in pure text mode (VGA console or framebuffer), without starting X.

Dell Precision notebook with 
AMD Radeon (TM) Pro WX 3200 Series (POLARIS12, DRM 3.39.0, 5.9.15-gentoo, LLVM 11.0.0) (0x6981)

Tried all combinations of DC/non-DC, FB/non-FB kernel configurations
(even happens when configuring Amdgpu without framebuffer!).

Many thanks for any help!

-- 
Prof. Dr. Klaus Kusche
Private address: Rosenberg 41, 07546 Gera, Germany
+49 365 20413058 klaus.kusche at computerix.info https://www.computerix.info
Office address: DHGE Gera, Weg der Freundschaft 4, 07546 Gera, Germany
+49 365 4341 306 klaus.kusche at dhge.de https://www.dhge.de