[Bug 73694] [hsw DP] Ubuntu 12.04 unable to use external monitor through edock

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=73694

--- Comment #22 from tobs76 at trashmail.de ---
(In reply to comment #2)
> Created attachment 92231 [details] [review]
> reverse dp link params selection
> 
> Please test the attached patch. If it doesn't work out please boot with
> drm.debug=0xe and attach the complete dmesg.

Hello Daniel Vetter,

sorry, but your patch makes things worse.

With kernel 3.15.7 (that includes your patch), I get lots of these messages
when I do Alt-F1 to switch from X to console. The monitor connected via display
port stays black:

[ 1775.967734] [drm:intel_dp_complete_link_train] *ERROR* failed to train DP,
aborting
[ 1776.016555] [drm:intel_dp_start_link_train] *ERROR* too many voltage
retries, give up
[ 1776.031180] [drm:intel_dp_start_link_train] *ERROR* too many voltage
retries, give up
[ 1776.045291] [drm:intel_dp_start_link_train] *ERROR* too many voltage
retries, give up
[ 1776.059590] [drm:intel_dp_start_link_train] *ERROR* too many voltage
retries, give up
[ 1776.074084] [drm:intel_dp_start_link_train] *ERROR* too many voltage
retries, give up
[ 1776.088169] [drm:intel_dp_start_link_train] *ERROR* too many voltage
retries, give up
[ 1776.102208] [drm:intel_dp_start_link_train] *ERROR* too many voltage
retries, give up
[ 1776.103948] [drm:intel_dp_complete_link_train] *ERROR* failed to train DP,
aborting
[ 1776.532617] [drm:intel_dp_start_link_train] *ERROR* too many voltage
retries, give up
[ 1776.546898] [drm:intel_dp_start_link_train] *ERROR* too many voltage
retries, give up
[ 1776.560964] [drm:intel_dp_start_link_train] *ERROR* too many voltage
retries, give up
[ 1776.575010] [drm:intel_dp_start_link_train] *ERROR* too many voltage
retries, give up
[ 1776.589319] [drm:intel_dp_start_link_train] *ERROR* too many voltage
retries, give up
[ 1776.603417] [drm:intel_dp_start_link_train] *ERROR* too many voltage
retries, give up
[ 1776.617493] [drm:intel_dp_start_link_train] *ERROR* too many voltage
retries, give up
[ 1776.619235] [drm:intel_dp_complete_link_train] *ERROR* failed to train DP,
aborting
[ 1776.669307] [drm:intel_dp_start_link_train] *ERROR* too many voltage
retries, give up
[ 1776.683639] [drm:intel_dp_start_link_train] *ERROR* too many voltage
retries, give up
[ 1776.697915] [drm:intel_dp_start_link_train] *ERROR* too many voltage
retries, give up
[ 1776.711962] [drm:intel_dp_start_link_train] *ERROR* too many voltage
retries, give up
[ 1776.726033] [drm:intel_dp_start_link_train] *ERROR* too many voltage
retries, give up
[ 1776.740120] [drm:intel_dp_start_link_train] *ERROR* too many voltage
retries, give up
[ 1776.754225] [drm:intel_dp_start_link_train] *ERROR* too many voltage
retries, give up
[ 1776.756172] [drm:intel_dp_complete_link_train] *ERROR* failed to train DP,
aborting


With kernel 3.13.0, I get only one batch of these messages, but the monitor was
working correctly.

My setup is:
Ubuntu trusty 14.04
Intel on board graphic
One monitor via display port, one monitor via analog VGA connector (15pin).

I tried the new kernel to debug another problem and stumbled upon this issue.

I suggest you revert your patch on upcoming linux or make it configurable.

Best regards,
Tobias

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