Booting Linux with 'Switchable Graphics' option in BIOS causes SDDM not to load.

[DonArt-Q]

I wanted to be able to control my brightness on my Lenovo Legion 5 15ARH05H laptop, so I tried selecting the 'Switchable Graphics' mode in BIOS, and it boots much faster than with the 'Discrete Graphics' option in the BIOS, but when I do this, SDDM doesn't load, and I'm not able to switch to any other TTY.

I have had this issue with Linux Zen and Linux kernels.

Does anyone know how to fix this?

[antony-jr]

I use SDDM and use openSUSE kernel. I have no issues like this. Maybe there is some wrong X.org config. I tried Garuda linux too and it works out of the box with switchable graphics. Also it uses the linux zen kernel by default. You give the live iso a try.

[Yato202010]

It's because your principal monitor is set to Nvidia and you probably didn't register the amd card in your xorg.conf . you could use the default arch xorg.conf to solve the problems this solve it for me when I had the same problems ( never run the Nvidia xorg config generators it break the config ^^' ) https://wiki.archlinux.org/title/Xorg#Using_xorg.conf

But I didn't understand why we can't access the tty this shouldn't be related but whatever this fix it for me 😅 ( always back up when doing some change to config )

[fuzunspm]

do you have any other solution? I don't have nvidia generated xorg.conf file but switchable graphics option on bios won't boot

[antony-jr]

@fuzunspm What distro and linux kernel are you using? (I use openSUSE and 6.3.x) and switchable graphics is working. But I got stuck on SDDM too when I had nvidia xorg org, when I commented it out, amdgpu worked fine. If you have newer Lenovo Legion then you might have a different issue altogether.

OS: openSUSE Tumbleweed x86_64 
Host: 82B5 Lenovo Legion 5 15ARH05 
Kernel: 6.3.7-1-default 
Resolution: 1920x1080 
DE: Plasma 5.27.6 
CPU: AMD Ryzen 7 4800H with Radeon Graphics (16) @ 2.900GHz 
GPU: AMD ATI 05:00.0 Renoir 
GPU: NVIDIA GeForce GTX 1650 Ti Mobile 

My xorg configs from /usr/share/X11/xorg.conf.d/

10-amdgpu.conf

# No need to comment this when you enable
# Discrete Graphics
Section "OutputClass"
        Identifier "AMDgpu"
        MatchDriver "amdgpu"
        Driver "amdgpu"
        Option "HotplugDriver" "amdgpu"
EndSection

10-nvidia.conf

# Uncomment below when using discrete
# graphics card.
#Section "Device"
#    Identifier "nvidia"
#    Driver "nvidia"
#    BusID "PCI:1:0:0"
#    Option "DPI" "96 x 96"
#    Option "AllowEmptyInitialConfiguration"
#    Option "AllowExternalGpus"
#    Option "RegistryDwords" "EnableBrightnessControl=1"
#EndSection

My Kernel Parameters as of now

nvidia.NVreg_RegistryDwords=EnableBrightnessControl=1 acpi_backlight=native nosimplefb=1

[antony-jr]

But I do advice everyone to use discrete graphics when you are planing to present something on a projector or tv, HDMI only works good in Nvidia graphics with this laptop. I tried HDMI with switchable graphics and it was a disaster, computer become so slow, I have no clue why.

[fuzunspm]

I tried many things but solution was setting switchable graphics on bios first then install Fedora. Now I use AMD GPU only on hybrid mode and use NVIDIA whenever I want. I never tried external display until now. Let's see how it goes but I guess worst case scenario i could just enable NVIDIA only mode, right?