subtle graphics corruption after resume on sandybridge laptop

[Sage Weil]

Binary package hint: xorg

The laptop is a samsung np900x3a. After a suspend/resume, everything looks mostly fine, except:
 - typing in a terminal is mostly invisible, until several lines go by and the text becomes visible.
 - flipping to a different desktop and back makes the text appear
 - the problem goes away if I log out/in of the x session
I'd attach a picture, but it wouldn't show anything useful except the unchanged screen (despite me typing) or the newly visible text (once it finally redraws).
Nothing suspicious in dmesg or Xorg.0.log that i can see...

ProblemType: Bug
DistroRelease: Ubuntu 11.04
Package: xorg 1:7.6+4ubuntu3
ProcVersionSignature: Ubuntu 2.6.38-8.42-generic 2.6.38.2
Uname: Linux 2.6.38-8-generic x86_64
Architecture: amd64
CompizPlugins: No value set for `/apps/compiz-1/general/screen0/options/active_plugins'
CompositorRunning: None
DRM.card0.DP.1:
 status: disconnected
 enabled: disabled
 dpms: Off
 modes:
 edid-base64:
DRM.card0.HDMI.A.1:
 status: disconnected
 enabled: disabled
 dpms: Off
 modes:
 edid-base64:
DRM.card0.LVDS.1:
 status: connected
 enabled: enabled
 dpms: On
 modes: 1366x768
 edid-base64: AP///////wBMo0YzAAAAAAAVAQOAHRB4Cof1lFdPjCcnUFQAAAABAQEBAQEBAQEBAQEBAQEBnhtWeFAAGDAwICUAJaUQAAAZAAAADwAAAAAAAAAAAB60AnQAAAAA/gBTQU1TVU5HCiAgICAgAAAA/gBMU04xMzNBVDAxODAxAF0=
DRM.card0.VGA.1:
 status: disconnected
 enabled: disabled
 dpms: Off
 modes:
 edid-base64:
Date: Sun May 29 15:51:29 2011
DistUpgraded: Fresh install
DistroCodename: natty
DistroVariant: ubuntu
GraphicsCard:
 Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller [8086:0116] (rev 09) (prog-if 00 [VGA controller])
   Subsystem: Samsung Electronics Co Ltd Device [144d:c098]
InstallationMedia: Ubuntu 11.04 "Natty Narwhal" - Release amd64 (20110427.1)
MachineType: SAMSUNG ELECTRONICS CO., LTD. 90X3A
ProcEnviron:
 LANGUAGE=en_US:en
 PATH=(custom, user)
 LANG=C
 SHELL=/bin/bash
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-2.6.38-8-generic root=UUID=5dbc24ee-272a-41ef-9846-c10799e58402 ro quiet splash vt.handoff=7
Renderer: Unknown
SourcePackage: xorg
Symptom: display
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 03/08/2011
dmi.bios.vendor: Phoenix Technologies Ltd.
dmi.bios.version: 04HL
dmi.board.asset.tag: Base Board Asset Tag
dmi.board.name: 90X3A
dmi.board.vendor: SAMSUNG ELECTRONICS CO., LTD.
dmi.board.version: FAB1
dmi.chassis.asset.tag: Asset Tag
dmi.chassis.type: 9
dmi.chassis.vendor: SAMSUNG ELECTRONICS CO., LTD.
dmi.chassis.version: 0.1
dmi.modalias: dmi:bvnPhoenixTechnologiesLtd.:bvr04HL:bd03/08/2011:svnSAMSUNGELECTRONICSCO.,LTD.:pn90X3A:pvr0.1:rvnSAMSUNGELECTRONICSCO.,LTD.:rn90X3A:rvrFAB1:cvnSAMSUNGELECTRONICSCO.,LTD.:ct9:cvr0.1:
dmi.product.name: 90X3A
dmi.product.version: 0.1
dmi.sys.vendor: SAMSUNG ELECTRONICS CO., LTD.
version.compiz: compiz 1:0.9.4+bzr20110415-0ubuntu2
version.ia32-libs: ia32-libs N/A
version.libdrm2: libdrm2 2.4.23-1ubuntu6
version.libgl1-mesa-dri: libgl1-mesa-dri 7.10.2-0ubuntu2
version.libgl1-mesa-dri-experimental: libgl1-mesa-dri-experimental N/A
version.libgl1-mesa-glx: libgl1-mesa-glx 7.10.2-0ubuntu2
version.xserver-xorg: xserver-xorg 1:7.6+4ubuntu3
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:6.14.0-0ubuntu4
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.14.0-4ubuntu7.1
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:0.0.16+git20110107+b795ca6e-0ubuntu7

[Sage Weil (sage-newdream)]

Here is dmesg _after_ a resume while the display is still behaving poorly

[Sage Weil (sage-newdream)]

Here's xorg.0.log while it's misbehaving

[Sage Weil (sage-newdream)]

I think this is the upstream bug:

https://bugs.freedesktop.org/show_bug.cgi?id=33487

[Chris Halse Rogers (raof)]

Do you still see this problem? FBC is now turned off by default, so this should no longer occur.

There are two upstream commits in 3.1-rc1 that are reported to fix the cause. Handing off to the kernel team. These patches are low priority, though - our default setup shouldn't hit this bug now.

commit 7782de3bd671657674e7baba854f0fd43e9f86bc
Author: Chris Wilson <email address hidden>
Date: Fri Jul 8 12:22:41 2011 +0100

    drm/i915: Disable FBC across page-flipping

commit 9ce9d0695d15da23ffe817516ba5d0b58caf8d05
Author: Chris Wilson <email address hidden>
Date: Fri Jul 8 12:22:40 2011 +0100

    drm/i915: Set persistent-mode for ILK/SNB framebuffer compression

[Sage Weil (sage-newdream)]

I'm running 3.0 + the patch below without problems. Not sure which upstream commit that was! Sorry, I havent have time to play with it once i got things working. :)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 0f1c799..4ed1ca5 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -1606,6 +1606,8 @@ static void ironlake_enable_fbc(struct drm_crtc *crtc, unsigned long interval)
                I915_WRITE(SNB_DPFC_CTL_SA,
                           SNB_CPU_FENCE_ENABLE | dev_priv->cfb_fence);
                I915_WRITE(DPFC_CPU_FENCE_OFFSET, crtc->y);
+ /* Set persistent mode */
+ I915_WRITE(ILK_DPFC_CONTROL, 1 << 25);
                sandybridge_blit_fbc_update(dev);
        }