I3 on Raspberry Pi 4 with dual monitors

ARM Technical Assistance
#1

Hello! New forum user here, looking for a little guidance and hoping someone here might have some.

I have a 4GB Raspberry Pi 4 that I have installed Manjaro i3 20.08 on a standard SD card. Everything is working great but I am relatively new to the i3wm. I have two monitors I would like to use with the Pi (one is hooked up with a standard HDMI cable and the other is using a HDMI to DVI converter cable). They are different model monitors but both support a maximum resolution of 1080p.

Now on to my main question, with the Pi and i3 both monitors are working however the screen image is simply being mirrored. I would like to have the monitors be extended. I have tried using the “xrandr” utility to modify the displays but to me it seems that it is not detecting the monitors or displays correctly. It only outputs the following:

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

I have done my best to find a cause for this but nothing I have found really fits. I can provide any other configuration I have that might help troubleshoot this. My install is pretty much fresh out of the box. I feel like I am missing something simple.

#2

You can install a small tool such as arandr that allows you to create those configurations in a graphical way and save them for later use.

EDIT: also note that i3 and other Tiling window Managers usually extend the workspace to the different screens - noticeable by the different workspace numbers in the status bar. Each workspace can be filled with applications individually by switching to it (ALT+workspace no.) and run an application on it (ALT+d for application menu)

#3

I stumbled across the arandr tool before creating this post. I am unable to get arandr or xrandr to modify the display setup on the Pi4. I could be using them incorrectly. From my internet searches it seems that arandr and xrandr should be reporting back the two HDMI (or DVI) devices that I have connected but they do not seem to do that. They only ever discover the “Screen 0” device and connect the “default” display to that. Am I to attempt to create the HDMI-0 and HDMI-1 devices using xrandr on my own?

The tvservice utility reports back both devices correctly, so from that perspective I know that they are there.

What you mention with the workspaces is what I want. The way it currently is working if I am actively using workspace “1” it displays on both monitors. What I would like to have happen is workspace “1” be on “monitor 1” and workspace “2” be on “monitor 2”. Or some type of configuration similar to that. For example all odd workspace numbers could be assigned to a specific monitor and all even workspace numbers to the other.

#4

Hi. I wonder if someone can guide me here. I have the same problem. I can’t change the monitor resolution setting, so I have a hard time reading the screen, I need to change the resolution from 1920 x 1080, to 1280x720_60.00, but it is not available. Thank you very much in advance.

inxi -G

Graphics: Device-1: display-subsystem driver: rockchip_drm v: N/A
Device-2: rk3399-dw-hdmi driver: dwhdmi_rockchip v: N/A
Device-3: rk3399-mali driver: panfrost v: kernel
Display: x11 server: X.Org 1.20.9 driver: fbturbo resolution: 1920x1080~N/A
OpenGL: renderer: llvmpipe (LLVM 10.0.1 128 bits) v: 3.3 Mesa 20.1.7

#5

Hi, I’m having the same issue as the original post but I’m using Xfce on a Pi 400. It seems to be related to the fbturbo driver. Once removed, extended monitors return. I would still like to use the fbturbo driver. It seems much snappier then modsetting and YouTube videos play better. -Thanks