RE: [3.4 regression] [bisected] DisplayPort fails to come on

[Brown, Len]

Wouter,
Please test the latest patch here:

https://bugzilla.kernel.org/show_bug.cgi?id=43168

thanks,
Len Brown, Intel Open Source Technology Center


> > When I cold boot 3.4 on my laptop the second monitor attached to the
> > displayport stays blank. It works fine with 3.3.8 and earlier.
> >
> > I get two error messages in dmesg:
> >
> > kernel: video: probe of LNXVIDEO:00 failed with error -5
> >
> > kernel: [drm:intel_dp_complete_link_train] *ERROR* failed to train DP,
> > aborting
> >
> > When I warm boot 3.4 after running kernel 3.3.8 first, only the first
> > message appears and the display works fine.
> >
> > A bisection based on the occurrence of the first error message
> > resulted in
> >
> > Author: Igor Murzov <intergalactic.anonymous@xxxxxxxxx>  2012-03-30
> > 18:32:08
> > Committer: Len Brown <len.brown@xxxxxxxxx>  2012-03-30 20:44:05
> > Parent: c16fa4f2ad19908a47c63d8fa436a1178438c7e7 (Linux 3.3)
> > Branches: linux-3.4.y, remotes/origin/linux-3.4.y,
> > remotes/origin/master
> > Follows: v3.3
> > Precedes: v3.4-rc1
> >
> >    ACPI video: Harden video bus adding.
> >
> >    It is always better to check return values, so add some new checks
> > and
> >    correct existing ones.
> >
> >    v2: Be consistent and don't mix errors from -E* and AE_* namespaces.
> >
> >    Signed-off-by: Igor Murzov <e-mail@xxxxxxx>
> >    Signed-off-by: Len Brown <len.brown@xxxxxxxxx>
> >
> >
> > The laptop is a Dell System XPS L702X/0XN71K, BIOS A17 02/22/2012. It
> > has two graphics card in Optimus configuration:
> > 00:02.0 VGA compatible controller: Intel Corporation 2nd Generation
> > Core Processor Family Integrated Graphics Controller (rev 09)
> > 01:00.0 VGA compatible controller: NVIDIA Corporation Device 124d (rev
> > a1)
> >
> > I only use the Intel card (which drives the DP port if I am not
> > mistaken)
> >
> > I hope this is helpful. Please let me know what I can do next to track
> > this problem down.
> >
> > With kind regards,
> >
> > Wouter Koolen
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