Comment # 27 on bug 108577 from Duncan Roe

(In reply to Alex Deucher from comment #24)
> Does just removing this line from the code:
> value |= 0x84;
> also fix the issue?

No, I get the black screen again. To be clear, I applied the patch in 
Attachment 142382 [details] to Linux 4.19 stable commit
84df9525b0c27f3ebc2ebb1864fa62a97fdedb7d