Bug 105651 - Vega64 doesn't output properly onto dell up2715k at 5120x2880
Summary: Vega64 doesn't output properly onto dell up2715k at 5120x2880
Alias: None
Product: DRI
Classification: Unclassified
Component: DRM/AMDgpu (show other bugs)
Version: unspecified
Hardware: Other All
: medium normal
Assignee: Default DRI bug account
QA Contact:
Depends on:
Reported: 2018-03-21 09:35 UTC by spgle212
Modified: 2019-08-19 13:42 UTC (History)
5 users (show)

See Also:
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Description spgle212 2018-03-21 09:35:12 UTC
I have tested 4.16 and drm-next-4.17 both under wayland and xorg. All only show the monitor as 2 displays with 2560x2880 side by side.
(I previously had an nvidia gpu using their binary blob on this display without issue)
Comment 1 Harry Wentland 2018-03-22 14:11:19 UTC
amdgpu doesn't currently have support for tiled displays. It's expected with tiled displays that you see them as you describe.
Comment 2 Alex Deucher 2019-02-16 23:28:52 UTC
This is handled at the Desktop level.  There are quite a few large format displays that show up as multiple DP MST displays, even a number of early 4k displays.  X exposes the tile info via randr 1.5 and the desktop environment should handle it as a single monitor.  Mutter handles this in GNOME for example.

Comment 3 spgle212 2019-04-27 20:20:54 UTC
Yes it is handled at Desktop level. (https://gitlab.gnome.org/GNOME/mutter/issues/110)

But the tile property has to be exposed from kernel driver as far as i understand. Which was not the case in my setup with amdgpu. With the new patch from here https://gitlab.freedesktop.org/xorg/driver/xf86-video-amdgpu/merge_requests/32 it should work but i can not see any tiled properties.
Comment 4 spgle212 2019-06-24 10:11:55 UTC
For this to work the TILE property (blob) of the connector has to be exposed. modetest does not return it.
Comment 5 spgle212 2019-06-24 10:23:23 UTC
xrandr --props also does not return the tile property.
Comment 6 Redsandro 2019-08-19 12:44:11 UTC
I'm having the same issue with a 4K Dell UP2414Q with 3840x2160 as 1920x2160+0+0, 1920x2160 +1920+0.

Is it possible to do a workaround in xorg.conf, similar to nVidia's TwinView and nvidiaXineramaInfoOrder as described in this question?

Comment 7 Alex Deucher 2019-08-19 12:48:57 UTC
You need to be using the amdgpu driver if you are running xorg.  I'm not sure if the modesetting driver supports the tile property yet.
Comment 8 Tomas Bzatek 2019-08-19 12:52:23 UTC
FYI starting with kernel 5.2 the tile property is propagated properly on Dell UP2715K. The Mate desktop picks this up just fine.
Comment 9 Redsandro 2019-08-19 13:42:17 UTC
@AlexDeucher I am using xserver-xorg-video-amdgpu. I can use 18.0.1 (No TILE support, need workaround) or 19.0.1 (Cinnamon crashes, need workaround for time being). I'm looking for a xorg config or xrandr command that works like nVidia's TwinView that I can keep in place while I am checking TILE support with this DM and kernel from time to time. (I am new to AMD/Radeon.)

@TomasBzatek I still need a workaround because Cinnamon crashes on 5.2 w/ 19.0.1 TILE support. See https://github.com/linuxmint/cinnamon/issues/8807

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