** Description changed:

  1)
  
- Mint Version: Linux Mint 17 Cinnamon 32 bit, 
+ Mint Version: Linux Mint 17 Cinnamon 32 bit,
  Kernel Version: 3.13.0-29-generic
  Laptop: Acer Extensa 5220
  Chipset: Intel GM965/GL960 (GMA X3100)
- Suspected driver at fault: xf86-video-intel 
+ Suspected driver at fault: xf86-video-intel
  
  2)
  
  Suspend and resume does not work reliably. After suspending, pressing
  any key or the power button causes the system to attempt to resume, but
  during the process it reboots instead of resuming. Only on rare
  occasions did resume work, so fault appeared intermittent.
  
  After much experimentation the following process confirms the bug is related 
to the Intel graphics driver and DDX 2D acceleration mode by changing X org 
config:
  - test suspend and resume with Option "AccelMethod" "sna"and resume from 
suspend often fails and causes reboot
  - test suspend and resume with Option "AccelMethod" "uxa" and resume from 
suspend seems reliable (no reboot noticed yet)
-  
+ 
  Example config to test with
  /etc/X11/xorg.conf.d/20-intel.conf
-   Section "Device"
-      Identifier  "Intel Graphics"
-      Driver      "intel"
-      #Option      "AccelMethod"  "uxa"
-      Option      "AccelMethod"  "sna"
-   EndSection
+   Section "Device"
+      Identifier  "Intel Graphics"
+      Driver      "intel"
+      #Option      "AccelMethod"  "uxa"
+      Option      "AccelMethod"  "sna"
+   EndSection
  
  3) What happened?
  
  Laptop rebooted instead of resuming
  
  4) What you expected to happen instead.
  
  Expected resume to restore current session with windows previously open,
  etc
  
  5) If the problem happened once, sometimes, or always.
  
  Very frequent. I'd say only 1 in 10 resume attempts (with Option
  "AccelMethod" "sna") worked and the rest failed and caused a reboot.
  
  6) Other important observations and notes
  
  Attempted to follow some suggestions here: 
https://01.org/linuxgraphics/documentation/how-debug-suspend-resume-issues-0
  - resume from S3 suspend to RAM without mdm (display manager) running 
appeared to work fine, e.g. 'echo mem > /sys/power/state'
  - the default suspend via menu GUI in Cinnamon often caused the resume bug to 
surface
  - S4 hibernation worked fine and didn't seem to trigger the bug
  
  Found several similar bug reports for Intel 965 / X3100 type laptops and 
Intel drivers in Ubuntu 14.04 and or Kernel 3.13. My suspicion is newer Intel 
video drivers have caused a number of regressions in the latest Kernels, 
especially with older Intel Chipsets.
  - [TOSHIBA Satellite U400] suspend/resume failure: 
https://bugs.launchpad.net/ubuntu/+source/linux-meta/+bug/1290787
  - [965gm regression v3.13] TOSHIBA Satellite U400 intel GM965/GL960 
suspend/resume failure kernel 3.14 rc7, rc6, 3.13: 
https://bugs.freedesktop.org/show_bug.cgi?id=76520
  - [Dell Inspiron 1525] Cannot resume from suspend: 
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1331654
  - Bug#747247: Problem Solved: 
https://lists.debian.org/debian-kernel/2014/07/msg00179.html
  
  Similar bugs and fixes for drm/i915 already backported to ubuntu kernel 
3.13.0.35
  
http://changelogs.ubuntu.com/changelogs/pool/main/l/linux/linux_3.13.0-39.66/changelog
  * drm/i915: Avoid div-by-zero when pixel_multiplier is zero
-   - LP: #1347088
+   - LP: #1347088
  
  So the problem I had was additional issue not yet fixed by those previous 
patches. During reading up, I noticed that a change had occurred in the default 
acceleration method lntel drivers a while ago. I stumbled on other bugs like 
this one:
  - Re: Fonts in Firefox "crumble" (Mint 16 Mate RC): 
http://forums.linuxmint.com/viewtopic.php?f=47&t=151054&start=40
  - The workaround/fix was to switch back to "uxa"
  
  After more reading up:
  * Three backends backends available for accelerating DDX: UXA, SNA and glamor
  * DDX: Device Dependent X, and is part of the 2D graphics device driver which 
is hardware specific.
  * The old methode is UXA - (Unified Acceleration Architecture). More mature 
and introduced to support the GEM driver model.
  * The new methode is SNA - (Sandybridge's New Acceleration). Targets newer 
chipsets.
- * xf86-video-intel X.org driver in 13.1 uses the newer SNA acceleration by 
default.
+ * Ubuntu 14.04 xf86-video-intel X.org driver uses the newer SNA acceleration 
by default.
  
  My hardware was older (not SandyBridge), so reverting to the UXA
  acceleration option appears to be a promising workaround as using the
  SNA (default) option somehow triggers the resume bug. SNA is probably
  not well suited to or optimised for older graphics like X3100 :-/
  
  A possible solution is for upstream maintainers (or Mint/Ubuntu via a
  patch) to revert to UXA if older Intel hardware is present and not force
  the SNA default. The proper fix might be to trace how SNA acceleration
  causes the suspend resume regression bug to surface, but given the
  resume crashes and reboots the system, it's hard to find evidence in
  logs.

** Also affects: ubuntu
   Importance: Undecided
       Status: New

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https://bugs.launchpad.net/bugs/1390923

Title:
  Mint 17 fails to resume after suspend on Acer Extensa 5220 with Intel
  GM965/GL960 (GMA X3100) based graphics chipset

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