Comment 4 for bug 2063877

Deleting "quiet splash" is the better workaround, rather than "nomodeset". I can confirm that without either "quiet splash" AND "nomodeset" in GRUB all energy saving works in the HP notebook with AMD Radeon Integrated Graphics (see above).

The following is copied from https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2063983 :

I followed this advice: https://www.reddit.com/r/Kubuntu/comments/1cdko49/comment/l1uf573/?utm_source=share&utm_medium=web3x&utm_name=web3xcss&utm_term=1&utm_content=share_button

It seems that "quiet splash" is the actual problem, not "nomodeset" (solution).

I edited the GRUB entry as follows (with results added):

1) With only "quiet splash" (no "nomodeset"), default installation, fresh install of Kubuntu 24.04: only black screen, nothing happens.

2) Add "nomodeset" to "quiet splash": everything works perfectly. Also works permanently with editing of /etc/default/grub.

3) Delete "quiet splash" in GRUB and do not add "nomodeset" (or delete "nomodeset", if previously added): everything works perfectly (see Reddit link above).

4) Delete "nomodeset", after having added it to /etc/default/grub and updated grub previously, but leave the 'original' "quiet splash": computer hangs, completely unresponsive, after showing the following code:

Booting a command list
Loading Linux 6.8.0-31-generic ...
Loading initial ramdisk ...

5) Again, boot without both "quiet splash" or "nomodeset": everything works perfectly. Also works permanently with /etc/default/grub.
It went quite fast, but after "Loading initial ramdisk ..." I think the next code line was "secure boot is enabled". It might be a problem with "secure boot" and "quiet splash". Secure boot is enabled in both my installations, so I can't try the other option ("secure boot" disabled in the EFI BIOS before installation).

Workaround (for me):
- Edit /etc/default/grub: the line "GRUB_CMDLINE_LINUX_DEFAULT=". Delete the words "quiet splash" (leave the quotation marks '').
- Run sudo update-grub