Bug 27979

Summary: [GM45] intel drm LVDSDDC_C: SDA stuck low!
Product: xorg Reporter: Vladimir Botka <vbotka>
Component: Driver/intelAssignee: Carl Worth <cworth>
Status: RESOLVED FIXED QA Contact: Xorg Project Team <xorg-team>
Severity: normal    
Priority: medium CC: eich, mat, sndirsch
Version: 7.5 (2009.10)   
Hardware: x86-64 (AMD64)   
OS: Linux (All)   
URL: https://bugzilla.novell.com/show_bug.cgi?id=602128
Whiteboard:
i915 platform: i915 features:
Attachments:
Description Flags
/var/log/messages; options drm debug=255 none

Description Vladimir Botka 2010-05-05 01:06:17 UTC 
Created attachment 35424 [details]
/var/log/messages; options drm debug=255

System environment:
-- chipset: GM45
-- system architecture: x86_64
-- xf86-video-intel: xorg-x11-driver-video 7.5
-- xserver: 7.5
-- mesa: 7.8.1
-- libdrm: 2.4.20
-- kernel: suse flavour 2.6.34-rc5-6-desktop
-- Linux distribution: openSUSE 11.3 MS6 Linux vaio 2.6.34-rc5-6-desktop
-- Machine or mobo model: Sony Vaio VGN-Z540
-- Display connector: 

Reproducing steps: start X

Additional info:

When I started X the screen was black and neither graphic not text console was working. Attached messages revealed:

May  4 16:29:07 vaio kernel: [ 4812.258631] intel drm LVDSDDC_C: SDA stuck low!
May  4 16:29:07 vaio kernel: [ 4812.258708] i915 0000:00:02.0: DDC bus
registration failed.
May  4 16:29:07 vaio kernel: [ 4812.258711] [drm:intel_lvds_init], No LVDS
modes found, disabling.
Comment 1 Vladimir Botka 2010-05-05 01:07:33 UTC 
added eich@pdx.freedesktop.org to CC
Comment 2 Vladimir Botka 2010-05-05 01:08:01 UTC 
added mhopf@suse.de to CC
Comment 3 Vladimir Botka 2010-05-05 01:08:27 UTC 
added sndirsch@suse.de to CC
Comment 4 Chris Wilson 2010-07-22 11:43:41 UTC 
commit f0217c42c9ab3d772e543f635ce628b9478f70b6
Author: Eric Anholt <eric@anholt.net>
Date:   Tue Dec 1 11:56:30 2009 -0800

    drm/i915: Fix DDC on some systems by clearing BIOS GMBUS setup.
    
    This is a sync of a fix I made in the old UMS code.  If the BIOS uses
    the GMBUS and doesn't clear that setup, then our bit-banging I2C can
    fail, leading to monitors not being detected.
    
    Signed-off-by: Eric Anholt <eric@anholt.net>

Use of freedesktop.org services, including Bugzilla, is subject to our Code of Conduct. How we collect and use information is described in our Privacy Policy.