Abomination

prepare_audio.sh

#!/bin/bash


# Check if we are executing as root
if [ $UID != 0 ]; then
    sudo ./prepare_audio.sh; exit
fi

# The nvidia driver cannot be loaded while we are configuring the GPU.
# Check whether the nvidia kernel is loaded:
if grep nvidia /proc/modules; then
    # It is. Check if we have HDMI audio
    if lspci | grep 01:00.1; then
        # Yes, so we are already done.
        echo "The following list should contain HDMI audio devices"
        aplay -l
        alsa reload
        echo "--> You are done!"; exit
    else
        # No, disable output through nvidia:
        #prime-select intel
	/etc/init.d/lightdm stop
	rmmod nvidia_drm nvidia_modeset nvidia_uvm nvidia
    fi
fi

# Make sure that the GPU is powered
if ! lspci -H1 | grep 01:00.0; then
    if ! grep OFF /proc/acpi/bbswitch; then
        echo "ERROR: GPU is listed in lspci -H1, but bbswitch thinks it is off"; exit 1
    fi
    # Turn on the discrete GPU (to get it listed in `lspci -H1`)
    echo ON > /proc/acpi/bbswitch
    if ! grep ON /proc/acpi/bbswitch; then
        echo "ERROR: Failed to turn on the GPU"; exit 1
    fi
fi

# Check if the GPU's audio chip is powered
if ! lspci -H1 | grep 01:00.1; then
    echo "Suspend the pc and resume it again. This will turn on the audio chip on the discrete GPU. Afterwards rerun this script."; exit
fi

# The output of 'lscpi -H1' should now contain 2 lines similar to:
# 01:00.0 VGA compatible controller: NVIDIA Corporation GF116M [GeForce GT 555M/635M] (rev a1)
# 01:00.1 Audio device: NVIDIA Corporation GF116 High Definition Audio Controller (rev a1)

# Now we need to rescan for the GPU such that the audio chip is found as well
if lspci | grep 01:00.0; then
    # Now we 'unmount' the GPU
    # the nvidia driver is not loaded, otherwise this step would eventualy cause your computer to freeze/hang
    echo 1 > /sys/bus/pci/devices/0000\:01\:00.0/remove
    # Wait a bit
    sleep 5
    # Check if this succeeded
    if lspci | grep 01:00.0; then
        echo "ERROR: Failed to remove the GPU (or so it seems, you can try again)"; exit 1
    fi
fi

if ! lspci | grep 01:00.0; then
    # Rescan
    echo 1 > /sys/bus/pci/rescan
    if ! lspci | grep 01:00.1; then
        echo "ERROR: Rescan did not find the audio chip"; exit 1
    fi

    # The output of 'lspci' should now contain 2 lines similar to:
    # 01:00.0 VGA compatible controller: NVIDIA Corporation GF116M [GeForce GT 555M/635M] (rev a1)
    # 01:00.1 Audio device: NVIDIA Corporation GF116 High Definition Audio Controller (rev a1)

    # Now we are ready to restart X11 using the nvidia driver
    #prime-select nvidia
    modprobe nvidia_drm nvidia_modeset nvidia_uvm nvidia
    prime-select nvidia
    #/etc/init.d/lightdm start

fi

echo "ERROR: Something went wrong"; exit 1