Comment # 84 on bug 1177428 from Karl Mistelberger

(In reply to Takashi Iwai from comment #82)
> I guess it's kernel-firmware workaround, but hey, who knows :)
> 
> In anyway, assume that it'll keep working, and let's close now.
> Feel free to reopen if you encounter the same problem again.  Thanks.

Changed the monitor and the freeze upon suspend/resume is back:

3400G:~ # hwinfo --monitor
35: None 00.0: 10002 LCD Monitor                                
  [Created at monitor.125]
  Unique ID: rdCR.K1i5gxVmsEC
  Parent ID: GBI1.Tt0a+NI8vi1
  Hardware Class: monitor
  Model: "SAMSUNG LU28R55"
  Vendor: SAM "SAMSUNG"
  Device: eisa 0x1017 "LU28R55"
  Serial ID: "H4ZN302578"
  Resolution: 720x400@70Hz
  Resolution: 640x480@60Hz
  Resolution: 640x480@67Hz
  Resolution: 640x480@72Hz
  Resolution: 640x480@75Hz
  Resolution: 800x600@56Hz
  Resolution: 800x600@60Hz
  Resolution: 800x600@72Hz
  Resolution: 800x600@75Hz
  Resolution: 832x624@75Hz
  Resolution: 1024x768@60Hz
  Resolution: 1024x768@70Hz
  Resolution: 1024x768@75Hz
  Resolution: 1280x1024@75Hz
  Resolution: 1152x864@75Hz
  Resolution: 1280x720@60Hz
  Resolution: 1280x1024@60Hz
  Resolution: 3840x2160@60Hz
  Size: 632x360 mm
  Year of Manufacture: 2038
  Week of Manufacture: 50
  Detailed Timings #0:
     Resolution: 3840x2160
     Horizontal: 3840 4016 4104 4400 (+176 +264 +560) +hsync
       Vertical: 2160 2168 2178 2250 (+8 +18 +90) +vsync
    Frequencies: 594.00 MHz, 135.00 kHz, 60.00 Hz
  Driver Info #0:
    Max. Resolution: 3840x2160
    Vert. Sync Range: 50-75 Hz
    Hor. Sync Range: 30-135 kHz
    Bandwidth: 594 MHz
  Config Status: cfg=new, avail=yes, need=no, active=unknown
  Attached to: #12 (VGA compatible controller)

3400G:~ # journalctl -b -3 --grep amdgpu -o short-monotonic -p err 
-- Logs begin at Wed 2020-10-21 16:58:25 CEST, end at Thu 2020-10-29 16:00:08
CET. --
[  274.870164] 3400G kernel: amdgpu 0000:06:00.0: [drm:amdgpu_ib_ring_tests
[amdgpu]] *ERROR* IB test failed on gfx (-22).
[  377.490546] 3400G kernel: amdgpu 0000:06:00.0: [drm:amdgpu_ib_ring_tests
[amdgpu]] *ERROR* IB test failed on gfx (-110).
3400G:~ #