Problems with multiple monitors on Debian and Deepin systems
Problems with multiple monitors on Debian and Deepin systems
I just set up Deepin OS (built on Debian) and it’s really working well so far. The main problem is noticeable. One of my two monitors has no input at all—not even a black one. My BIOS uses the default graphics card, but with the APU enabled, that card is actually my GPU. The monitor without input is connected to the APU. When I switch the APU to default mode, the GPU’s display gets turned off. Both monitors function properly in Windows. Here are some commands I ran:
- lspci | grep VGA
Shows a VGA compatible controller from AMD/ATI, with Kaveri and Baffin models listed.
- xrandr --listproviders
Lists the available display providers (shows provider 0 and 1).
- Display settings in Windows also reflect these changes.
I’ve shared this info on Deepin OS forums, but I’m still seeking advice. Any suggestions would be really helpful!
Xorg struggles with multiple devices. It seems the faulty monitor is connected to another device. Are both monitors attached to the graphics card or is one on the motherboard? If both are on the card... Showing lspci -k will reveal the output. Each VGA device specifies kernel drivers or modules. You might avoid loading the built-in graphics driver by blacklisting it. In extreme cases, you'll need to define the device in your Xorg configuration files. For instance, in a folder like 20-device.conf you could have:
Section "Device" Identifier "Card0" Driver "amdgpu" BusID "PCI:1:0:0"
Section "Screen" Identifier "Screen0" Device "Card0" GPUDevice "Card0"
I own a wide-angle 1080p display at 75hz linked to the GPU, plus a standard 1080p screen at 60hz connected via the motherboard. At 00:01.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Kaveri [Radeon R7 Graphics]. System: Gigabyte Technology Co., Ltd. Kaveri [Radeon R7 Graphics]. Driver: radeon. Modules: radeon 01:00.0 VGA compatible controller. At 00:01.0 Baffin [Radeon RX 460] (rev cf). Module: XFX Pine Group Inc. Kernel driver: amdgpu. I’m planning to test this setup next. Appreciate the details! Edit: After adjusting several versions of your example config file, the Deepin OS startup logo now appears on one side. We’re really getting closer!
Can you connect both devices to the card? I’m not very familiar with motherboard inputs or on-board graphics. You might want to ignore that option. I’m not sure what will actually make the output respond after blacklisting. To do that, create a file called radeon.conf in /etc/modprobe.d and add blacklisting for radeon. After saving it, run the commands listed to update your system. Once that’s done, restart the machine so the changes take effect. The 20-device.conf can be removed since there won’t be multiple devices, but you can keep it just in case. If you run into issues, feel free to delete it.