If you're getting "firmware failed to leave lps state" spammed into your boot logs when you run
dmesg, there's a fix for that.
sudo sed -i 's/3/2/' /etc/NetworkManager/conf.d/*
-- or --
[connection] wifi.powersave = 2
0 = use the default value
1 = don't touch existing setting
2 = disable powersave
3 = enable powersave
One cause is that the network adapter power management isn't being properly managed by the UEFI, so we disable power management for the network adapter, and those errors go away.
This can also happen if Bluetooth power management isn't properly managed by the UEFI, but in my case that's not the case.
And apparently it can also happen if there's a problem with the charging circuitry on a laptop (voltage to the motherboard droops too much when the laptop is on battery), but again, that wasn't the case for me.
If you're getting that error, you might think about filing a bug report with your UEFI manufacturer so they can issue a fix. For consumer-grade HP machines, that UEFI manufacturer is Insyde Software.