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

Daniel Vetter
2012-06-14T14:05:42Z

On Thu, Jun 14, 2012 at 4:00 PM, Dave Airlie <airlied@gmail.com> wrote:
> On Thu, Jun 14, 2012 at 2:26 PM, Wouter M. Koolen
> <W.M.Koolen-Wijkstra@cwi.nl> wrote:
> cc'ing Daniel.
>
>> Hi Igor and Len,
>>
>> 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.

Ok, the second message is actually the one explaining the black
screen. Can you please boot with drm.debug=0xe added to your kernel
cmdline and attach the full dmesg, so we know a bit what your display
hw looks like?

Also, please redo the bisect if possible (with coldboots) and hunt for
the black screen/the "failed to train DP" message.

Thanks, Daniel
--
Daniel Vetter
daniel.vetter@ffwll.ch - +41 (0) 79 365 57 48 - http://blog.ffwll.ch