I am running Ubuntu 15.04 (Vivid Vervet) with 3.19.5-031905-generic #201504211114 kernel and GNOME Shell 3.14.4 on a Samsung NP370R4E laptop.
When I boot up, I see
[1.079026] ACPI PCC probe failed
starting version 219
on my screen but boot proceeds and I get to the log-in screen.
However, I am unable to adjust my screen brightness - it remains at maximum brightness when connected to a power source and doesn't budge when I use fn+f2 or f3 to change the brightness. Also, when shutting down or rebooting, machine hangs at the shut down splash screen (after sending the power off or reboot message) and I have to power off manually by holding the power button.
I used to be able to make the laptop sleep by closing the lid but that doesn't happen now either.
Also, I have been having these issues since 14.10 and it was due to these problems that I installed this upstream kernel after getting to 15.04 : I figured https://bugzilla.kernel.org/show_bug.cgi?id=84561 must have been committed to this release.
Edit : this isn't a duplicate of What is [ 0.4486641 ACPI PCC probe failed] starting version 219? : my computer does boot to the login screen and it isn't the case that my display manager isn't loading - gdm loads fine. Instead, ACPI appears to be completely unable to influence the power peripherals of my computer (if that is the right term)
Edit : is it alright for me to try and bump 84561 at bugzilla.kernel.org? Or is this even the place to ask this.