nb : for other noob like me, that'll save you the "how to" search :
sudo gedit /etc/default/grub
replace
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
with
GRUB_CMDLINE_LINUX_DEFAULT="i915.disable_power_well=0 quiet splash"
nb : for other noob like me, that'll save you the "how to" search :
sudo gedit /etc/default/grub
replace
GRUB_ CMDLINE_ LINUX_DEFAULT= "quiet splash"
with
GRUB_ CMDLINE_ LINUX_DEFAULT= "i915.disable_ power_well= 0 quiet splash"