Bug 106846 - RX480 with multiple HDMI ports shows monitor connected to unused port when using amdgpu.dc=1
Summary: RX480 with multiple HDMI ports shows monitor connected to unused port when us...
Status: RESOLVED FIXED
Alias: None
Product: DRI
Classification: Unclassified
Component: DRM/AMDgpu (show other bugs)
Version: unspecified
Hardware: x86-64 (AMD64) Linux (All)
: medium normal
Assignee: Default DRI bug account
QA Contact:
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Blocks:
 
Reported: 2018-06-07 08:29 UTC by Tim Carr
Modified: 2018-10-23 01:01 UTC (History)
1 user (show)

See Also:
i915 platform:
i915 features:

Attachments
'xrandr -q' output with and without amdgpu.dc enabled. (1.86 KB, text/plain)
2018-06-07 08:29 UTC, Tim Carr 		no flags Details
Xorg.log (44.12 KB, text/x-log)
2018-06-07 08:30 UTC, Tim Carr 		no flags Details
dmesg (72.00 KB, text/plain)
2018-06-07 08:30 UTC, Tim Carr 		no flags Details
dmesg with amdgpu.dc=0 (71.97 KB, text/plain)
2018-06-07 09:10 UTC, Tim Carr 		no flags Details
[PATCH] Report non-DP display as disconnected without EDID (1.48 KB, patch)
2018-08-01 19:49 UTC, Harry Wentland 		no flags Details | Splinter Review
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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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