Bug 106846

Summary: RX480 with multiple HDMI ports shows monitor connected to unused port when using amdgpu.dc=1
Product: DRI Reporter: Tim Carr <tim>
Component: DRM/AMDgpuAssignee: Default DRI bug account <dri-devel>
Status: RESOLVED FIXED QA Contact:
Severity: normal    
Priority: medium CC: harry.wentland
Version: unspecified   
Hardware: x86-64 (AMD64)   
OS: Linux (All)   
Whiteboard:
i915 platform: i915 features:
Attachments:
Description Flags
'xrandr -q' output with and without amdgpu.dc enabled.
none
Xorg.log
none
dmesg
none
dmesg with amdgpu.dc=0
none
[PATCH] Report non-DP display as disconnected without EDID none

Description Tim Carr 2018-06-07 08:29:24 UTC 
Created attachment 140060 [details]
'xrandr -q' output with and without amdgpu.dc enabled.

Card is an ASUS DUAL-RX480-04G. When booting with amdgpu.dc=1, as is default on 4.17+, the system shows a monitor on both HDMI ports when only one is connected. This causes a low-resolution login screen and requires disabling the non-existent monitor to prevent some windows from being opened off screen.

Attached is the 'xrandr -q' output from booting with and without amdgpu.dc enabled. Behavior is the same regardless of which HDMI port is used.
Comment 1 Tim Carr 2018-06-07 08:30:18 UTC 
Created attachment 140061 [details]
Xorg.log
Comment 2 Tim Carr 2018-06-07 08:30:46 UTC 
Created attachment 140062 [details]
dmesg
Comment 3 Michel Dänzer 2018-06-07 08:49:13 UTC 
Please also attach the dmesg output with amdgpu.dc=0.
Comment 4 Tim Carr 2018-06-07 09:10:59 UTC 
Created attachment 140064 [details]
dmesg with amdgpu.dc=0
Comment 5 Harry Wentland 2018-08-01 19:49:41 UTC 
Created attachment 140930 [details] [review]
[PATCH] Report non-DP display as disconnected without EDID

Can you see if this fixes it?
Comment 6 Tim Carr 2018-08-02 08:15:40 UTC 
That fixed it. Everything seems good.
Comment 7 Tim Carr 2018-10-23 01:01:56 UTC 
The patch for this was included in Kernel 4.19. Going ahead and marking it as resolved now that 4.19 is final.

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