Background

1. I have reinstalled 22.04.3, as I want a vanilla system before trying to learn about various enterprise applications. I have been running Ubuntu since the initial release of 22.04; this is the first reinstall since then.
2. I am fairly technical, but I have reached the limits of what I can do, and I need help with understanding the root cause of this problem, and how to resolve it. Happy to follow guidance and paste results here so others can learn.
3. I have looked for a solution here and elsewhere, but there is no consensus as to root cause. There are a myriad of possible solutions, with no explanation on cause. There is no fault-finding procedure I can follow. Some say linux-firmware, or the kernel are the problem, whilst others recommend running AMD-specific drivers will solve the problem (personally I think this makes the problem worse). Even if it does solve the problem, you never know what the cause was.

Problem

4. This is the main problem. Ubuntu is booting to a black screen. When quiet& splash are removed from Grub's kernel parameters, I see a quick listing of activity scroll on-screen, which then goes blank permanently.
5. On a fully functional system, said text scrolls, the screen blanks for a second, and the text is re-displayed more vibrantly. I think this is the video drivers kicking-in, hence the title of this post. Happy to be wrong; this is just my guess.
6. I can boot successfully using the latest kernel recovery option within Grub; I am typing this in recovery mode.
7. The only way I can install 22.04.3, is by using the latest kernel's safe graphics option. Choosing the normal option just results in a blank screen.

What I have tried

8. When installing 22.04 on first release, there was a problem with iommu, requiring amd_iommu=on& iommu=soft in order for the screen to work. I have tried these options, on Grub's kernel line, in place of quiet& splash, as well as at the end of that line, after vt_handoff (not at the same time in both location), but nothing has worked.
9. I have reinstalled linux-firmware and amd64-microcode, followed by update-grub. Confidence levels were low when doing this, but I did it anyway. Problem unresolved.
10. I suspect that when Grub calls function load_video, this is where the failure is, but I don't know how to troubleshoot from there. It looks like module all_video is loaded by the kernel, if Grub cannot ascertain what video card is in use. It makes sense to have a catch-all.

function load_video {if [ x$feature_all_video_module = xy ]; then insmod all_videoelse insmod efi_gop insmod efi_uga insmod ieee1275_fb insmod vbe insmod vga insmod video_bochs insmod video_cirrusfi}

I then don't understand how the various modules correlate to AMD video drivers.

11. lshw seems to back up my theory; unsure if this is showing like this because I have booted into safe mode.

michael@mitp-NL5xRU:/var/log$ sudo lshw -c video[sudo] password for michael:   *-display UNCLAIMED              description: VGA compatible controller       product: Renoir       vendor: Advanced Micro Devices, Inc. [AMD/ATI]       physical id: 0       bus info: pci@0000:04:00.0       version: c3       width: 64 bits       clock: 33MHz       capabilities: pm pciexpress msi msix vga_controller bus_master cap_list       configuration: latency=0       resources: iomemory:fc0-fbf iomemory:fc0-fbf memory:fce0000000-fcefffffff memory:fcf0000000-fcf01fffff ioport:1000(size=256) memory:d0400000-d047ffff  *-graphics       product: EFI VGA       physical id: 2       logical name: /dev/fb0       capabilities: fb       configuration: depth=32 resolution=1920,1080

12. As does gpu-manager.log

og_file: /var/log/gpu-manager.loglast_boot_file: /var/lib/ubuntu-drivers-common/last_gfx_bootnew_boot_file: /var/lib/ubuntu-drivers-common/last_gfx_bootcan't access /run/u-d-c-nvidia-was-loaded filecan't access /opt/amdgpu-pro/bin/amdgpu-pro-pxLooking for nvidia modules in /lib/modules/6.2.0-26-generic/kernelLooking for nvidia modules in /lib/modules/6.2.0-26-generic/updates/dkmsLooking for amdgpu modules in /lib/modules/6.2.0-26-generic/kernelLooking for amdgpu modules in /lib/modules/6.2.0-26-generic/updates/dkmsIs nvidia loaded? noWas nvidia unloaded? noIs nvidia blacklisted? noIs intel loaded? noIs radeon loaded? noIs radeon blacklisted? noIs amdgpu loaded? noIs amdgpu blacklisted? noIs amdgpu versioned? noIs amdgpu pro stack? noIs nouveau loaded? noIs nouveau blacklisted? noIs nvidia kernel module available? noIs amdgpu kernel module available? noVendor/Device Id: 1002:1636BusID "PCI:4@0:0:0"Is boot vga? yesError: can't access /sys/bus/pci/devices/0000:04:00.0/driverThe device is not bound to any driver.Error : Failed to open /dev/driError : Failed to open /dev/driError : Failed to open /dev/driError : Failed to open /dev/driDoes it require offloading? nolast cards number = 1Has amd? yesHas intel? no

Hardware

H/W path                Device     Class          Description=============================================================/0/0                               memory         128KiB BIOS/0/4                               processor      AMD Ryzen 5 4500U with Radeon Graphics/0/4/5                             memory         384KiB L1 cache/0/4/6                             memory         3MiB L2 cache/0/4/7                             memory         8MiB L3 cache/0/23                              memory         16GiB System Memory/0/23/0                            memory         8GiB SODIMM DDR4 Synchronous Unbuffered (Unregistered) 2400 MHz (0.4 ns)/0/23/1                            memory         8GiB SODIMM DDR4 Synchronous Unbuffered (Unregistered) 2133 MHz (0.5 ns)/0/100                             bridge         Renoir/Cezanne Root Complex/0/100/0.2                         generic        Renoir/Cezanne IOMMU/0/100/8.1                         bridge         Renoir Internal PCIe GPP Bridge to Bus/0/100/8.1/0                       display        Renoir/0/100/8.1/0.1          card0      multimedia     Renoir Radeon High Definition Audio Controller/0/100/8.1/0.1/0        input31    input          HD-Audio Generic HDMI/DP,pcm=3/0/100/8.1/0.1/1        input32    input          HD-Audio Generic HDMI/DP,pcm=7/0/100/8.1/0.2                     generic        Family 17h (Models 10h-1fh) Platform Security Processor/0/100/8.1/0.3                     bus            Renoir/Cezanne USB 3.1/0/100/8.1/0.3/0        usb1       bus            xHCI Host Controller/0/100/8.1/0.3/0/3                 input          USB Receiver/0/100/8.1/0.3/0/3/0    input25    input          Logitech Wireless Keyboard PID:4023/0/100/8.1/0.3/0/3/1    input26    input          Logitech Wireless Mouse/0/100/8.1/0.3/1        usb2       bus            xHCI Host Controller/0/100/8.1/0.4                     bus            Renoir/Cezanne USB 3.1/0/100/8.1/0.4/0        usb3       bus            xHCI Host Controller/0/100/8.1/0.4/0/3                 communication  AX200 Bluetooth/0/100/8.1/0.4/0/4      input27    multimedia     BisonCam,NB Pro: BisonCam,NB Pr/0/100/8.1/0.4/1        usb4       bus            xHCI Host Controller/0/100/8.1/0.5                     multimedia     Raven/Raven2/FireFlight/Renoir Audio Processor/0/100/8.1/0.6          card1      multimedia     Family 17h (Models 10h-1fh) HD Audio Controller/0/100/8.1/0.6/0        input33    input          HD-Audio Generic Front Headphone

If possible

1. They say a little knowledge can be dangerous; if the above is complete rubbish, then I'm sorry Can you point me to a detailed fault-finding procedure so I can follow, learn and correct please (if there is one)?
2. If there isn't one, can you help me troubleshoot this problem? I have tried to include above, what I think will help. If more information is required, please let me know.
3. Last but not least, thank you for taking the time to read this.