Bug 206387

Summary:	amdgpu with amdgpu.dc=1 and multiple monitors on DisplayPort keeps changing devices
Product:	Drivers	Reporter:	Alexandre Pereira (alexpereira)
Component:	Video(DRI - non Intel)	Assignee:	drivers_video-dri
Status:	NEW ---
Severity:	normal	CC:	alexdeucher, mrmazda, nate
Priority:	P1
Hardware:	All
OS:	Linux
Kernel Version:	5.5.0	Subsystem:
Regression:	No	Bisected commit-id:
Attachments:	xorg and dmesg log - boot 1 xorg and dmesg log - boot 2

Description Alexandre Pereira 2020-02-02 03:01:54 UTC

Hi,

I have an amd rx580 with 2 monitors connected by display port.
The 2 monitors are the same brand and model.

When using the amdgpu driver with amdgpu.dc=0, the device names ( DisplayPort-2 and DisplayPort-3 ) stay consistent, but when using amdgpu.dc=1, the device names change randomly ( or at least not consistent ).
They sometimes are DisplayPort-4 and DisplayPort-5 , sometimes DisplayPort-4 and DisplayPort-6, making me have to configure Xorg at every boot ( to correct the placement of the monitors, which is left and which is right ) and configure kde plasma and sway ( because they base their configurations on the device names ).

Currently I switched to using amdgpu.dc=1 because amdgpu.dc=0 locks computer after a wake up from suspend ( with amdgpu.dc=1 it does not ).

Thanks !

Comment 1 Alex Deucher 2020-02-03 16:24:22 UTC

Please attach your xorg log (if using X) and dmesg output.  dc support DP MST while the old dp=0 code does not.  With DP MST ports are added dynamically since you can have multiple DP monitors connected to a single physical port on the computer.

Comment 2 Alexandre Pereira 2020-02-03 19:48:04 UTC

Created attachment 287099 [details]
xorg and dmesg log - boot 1

Comment 3 Alexandre Pereira 2020-02-03 19:48:28 UTC

Created attachment 287101 [details]
xorg and dmesg log - boot 2

Comment 4 Alexandre Pereira 2020-02-03 19:50:07 UTC

Hi,

submitted two attachments, they have the xorg and dmesg log of bootup until login manager ( in this case sddm ) appears.

bootup 1 is the first reboot, and bootup 2 is a reboot right after getting the previous logs, nothing else was done in between.

Thanks.