(In reply to Michel Dänzer from comment #4)
> (In reply to Nicholas Kazlauskas from comment #3)
> > It's hitting the "." as part of the video mode and erroring out because DRM
> > doesn't consider it a valid character.
> 
> Or maybe there's two separate issues? Failure to parse the mode name
> shouldn't affect whether or not DC picks up EDID, should it?

I suppose that doesn't actually influence whether the EDID has been read or is
valid. So that's a different bug.

The "No EDID read." error comes from the result from drm_get_edid(...) being
NULL, however.

While we're responsible for the actual transfers to and from the receiver the
actual logic is shared there between drivers.

(In reply to Babblebones from comment #2)
> Created attachment 143957 [details]
> Dmesg output from an affected kernel
> 
> Here is the issue, you can see
> [    1.335096] [drm:dc_link_detect [amdgpu]] *ERROR* No EDID read.
> 
> Which is about where the display turns into fruit salad.
> Please let me know if I can submit any more debug info that would assist! I
> am very much in need of running a newer kernel.

Can you post a dmesg log with drm.debug=4 as part of your kernel boot
parameters?