Comment 53 for bug 1238194

@Peter:

I had the same issue after upgrading to 15.04. and this kernel module solved it. Maybe it helps in your case as well?

I added

hid-logitech-hidpp
to
 /etc/initramfs-tools/modules

then
sudo update-initramfs -u

as described here: http://askubuntu.com/questions/613139/ubuntu-15-04-usb-devices-powered-off-at-encrypted-root-password-prompt