[BUG] Rockchip VOP2 Mainline Resume from Suspend

[Chris Morgan]

I noticed a bug on the Rockchip mainline VOP2 driver where it fails to
resume from suspend.

I dumped the registers and noticed the following were changed between
working (pre-suspend) and non working (post-suspend) states.

pre: 0xfe0400b0: 0x00000030
post: 0xfe0400b0: 0x00000010

pre: 0xfe0400bc: 0x000003CD
post: 0xfe0400bc: 0x000003ED

pre:0xfe0400cc: 0x000000E3
post: 0xfe0400cc: 0x000000EF

pre: 0xfe04181c: 0x00000280
pre: 0xfe041820: 0x01DF027F
pre: 0xfe041824: 0x01DF027F
post: 0xfe04181c: 0x00000000
post: 0xfe041820: 0x00000000
post: 0xfe041824: 0x00000000

pre: 0xfe041830: 0x00000044
pre: 0xfe041834: 0x00000000
post: 0xfe041830: 0x00000000
post: 0xfe041834: 0x10001000

What's interesting is that if I write the pre-suspend values back the
display starts to work again. I assume this means something is missing
from the driver that needs to catch a resume from suspend scenario?

Let me know if there's any more I can do to help debug this further.
I'm not very knowledgeable on the DRM side of the house, but hopefully
this is enough information to find the issue.
Thank you.