Blank console but X11 works on MCP79 - old regression since 3.8

From: Ondrej Zary
Date: Fri Nov 17 2017 - 09:26:21 EST

I've just been hit by this old bug which is still present in 4.14:

On MCP79 (ION), when stolen memory is set to 32MB in BIOS, console is blank
but X11 works. When the stolen memory is increased to 64MB, console works

Bisected it to this:

4f6029da58ba9204c98e33f4f3737fe085c87a6f is the first bad commit
commit 4f6029da58ba9204c98e33f4f3737fe085c87a6f
Author: Ben Skeggs <bskeggs@xxxxxxxxxx>
Date: Fri Nov 16 11:54:31 2012 +1000

drm/nv50-nvc0: switch to common disp impl, removing previous version

Signed-off-by: Ben Skeggs <bskeggs@xxxxxxxxxx>

It's a big change so I'm not able to do more debugging.

Ondrej Zary