Screen backlight is OFF when resuming from suspend with vgaswitcheroo controlled cards

Bug #955046 reported by Marco Trevisan (Treviño)
This bug affects 6 people
Affects Status Importance Assigned to Milestone
linux (Ubuntu)

Bug Description

Using vgaswitcheroo to disable the integrate or discrete card could lead to some troubles when resuming from suspension (to RAM or disk as well). Basically, the computer monitor backlight could be not be turned on again when resuming from suspension.

To me it happens this:
 - I disable the integrated card
 - Suspend
 - Resume: no monitor backlight is on

At this point doing what mentioned below fix the issue, but it must be done by SSH or by memory :):
  echo DIGD > /sys/kernel/debug/vgaswitcheroo/switch
  echo OFF > /sys/kernel/debug/vgaswitcheroo/switch

So, the easiest and clean fix should be to add a sleep.d script something like:


if [ -e /sys/kernel/debug/vgaswitcheroo/switch ]; then
  case "$1" in
      echo ON > /sys/kernel/debug/vgaswitcheroo/switch
      echo OFF > /sys/kernel/debug/vgaswitcheroo/switch

This would fix the issue for vgaswitcheroo users and won't touch the others.

Changed in linux:
importance: Unknown → Medium
status: Unknown → Confirmed
Changed in linux (Ubuntu):
importance: Undecided → Medium
Changed in pm-utils (Ubuntu):
importance: Undecided → Medium
Revision history for this message
Launchpad Janitor (janitor) wrote :

Status changed to 'Confirmed' because the bug affects multiple users.

Changed in linux (Ubuntu):
status: New → Confirmed
Changed in pm-utils (Ubuntu):
status: New → Confirmed
Revision history for this message
Kevin M (sumpfomat) wrote :

Please note that on some notebooks (e.g. ACER 3820 TG) the ON thingy does change the muxes when called with a switched off discrete card. This results in a black screen which can be "repaired" by calling MIGD to change the mux to the desired integrated card. See my bug for a sleep.d script which takes this into account:

description: updated
Revision history for this message
Christopher M. Peñalver (penalvch) wrote :

Marco Trevisan (Treviño), this bug was reported a while ago and there hasn't been any activity in it recently. We were wondering if this is still an issue? If so, could you please test for this with the latest development release of Ubuntu? ISO images are available from .

If it remains an issue, could you please run the following command in the development release from a Terminal (Applications->Accessories->Terminal), as it will automatically gather and attach updated debug information to this report:

apport-collect -p linux <replace-with-bug-number>

tags: added: needs-kernel-logs needs-upstream-testing
Changed in linux (Ubuntu):
status: Confirmed → Incomplete
no longer affects: pm-utils (Ubuntu)
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