Second monitor not detected

Question

I'm using Debian Buster, XFCE 4.12 as my DE, with an AMD RX 580 graphics card.

I have my primary monitor plugged on an HDMI port, and I wanted to use a secondary monitor on the DVI port, but this one is not detected.

At startup, the boot text is mirrored on both monitors, but at the lightdm greeter, only my primary monitor is on.

When I go to Settings > Display, only my primary monitor is detected

Only that display is detected by xrandr as well.

Additional info

lshw -c video

outputs

  *-display UNCLAIMED       
       description: VGA compatible controller
       product: Polaris 20 XL [Radeon RX 580 2048SP]
       vendor: Advanced Micro Devices, Inc. [AMD/ATI]
       physical id: 0
       bus info: pci@0000:06:00.0
       version: ef
       width: 64 bits
       clock: 33MHz
       capabilities: pm pciexpress msi vga_controller bus_master cap_list
       configuration: latency=0
       resources: memory:e0000000-efffffff memory:f0000000-f01fffff ioport:e000(size=256) memory:fe900000-fe93ffff memory:c0000-dffff

And for xrandr

xrandr

outputs

xrandr: Failed to get size of gamma for output default
Screen 0: minimum 640 x 480, current 1920 x 1080, maximum 1920 x 1080
default connected 1920x1080+0+0 0mm x 0mm
   1920x1080      0.00* 
   1440x900       0.00  
   640x480        0.00  

And info about the OS and the kernel

uname -a

outputs

Linux debian-prout 4.19.0-5-amd64 #1 SMP Debian 4.19.37-5 (2019-06-19) x86_64 GNU/Linux

I suspect it is a problem with my drivers, but I can't figure out how to install/update them properly yet. I can see some text related to amdgpu firmware when I boot, but it's too fast I can't catch it.

What should I fix?

Answer 1

I somehow managed to make it work.

I tried installing some drivers I may need, like xserver-xorg-video-ati as I already had xserver-xorg-video-amdgpu installed, and at the end of the installation, I had a lot of warning messages saying that some files starting with vega20 were missing in /lib/firmware/amdgpu

I was able to find and download the files from here and copied them to said directory.

-rw-r--r--  vega20_asd.bin  78336   logstatsplain
-rw-r--r--  vega20_ce.bin   9344    logstatsplain
-rw-r--r--  vega20_me.bin   17536   logstatsplain
-rw-r--r--  vega20_mec.bin  268048  logstatsplain
-rw-r--r--  vega20_mec2.bin 268048  logstatsplain
-rw-r--r--  vega20_pfp.bin  21632   logstatsplain
-rw-r--r--  vega20_rlc.bin  32052   logstatsplain
-rw-r--r--  vega20_sdma.bin 17408   logstatsplain
-rw-r--r--  vega20_sdma1.bin    17408   logstatsplain
-rw-r--r--  vega20_smc.bin  262912  logstatsplain
-rw-r--r--  vega20_sos.bin  166800  logstatsplain
-rw-r--r--  vega20_uvd.bin  379328  logstatsplain
-rw-r--r--  vega20_vce.bin  165408  logstatsplain

After a reboot, only the monitor on the DVI port was active and found by xrandr and the display settings, but then, I checked the Configure new displays when connected, unplugged and re-plugged the HDMI output, and I was able to chose whether I wanted to mirror or extend the displays.

And as asked by Paradox in the comment, I only used drivers from the debian package, and the files listed above were manually downloaded and copied to the /lib/firmware/amdgpu directory.