Bug 78987 - black screen when trying to enable external VGA screen on Trinity APU laptop
Summary: black screen when trying to enable external VGA screen on Trinity APU laptop
Status: RESOLVED FIXED
Alias: None
Product: DRI
Classification: Unclassified
Component: DRM/Radeon (show other bugs)
Version: XOrg git
Hardware: Other All
: medium major
Assignee: Default DRI bug account
QA Contact:
URL:
Whiteboard:
Keywords:
Depends on:
Blocks:
 
Reported: 2014-05-20 21:24 UTC by Lucas Stach
Modified: 2016-06-19 12:36 UTC (History)
0 users

See Also:
i915 platform:
i915 features:


Attachments
dmesg from failing machine (8.90 KB, text/plain)
2014-05-20 21:24 UTC, Lucas Stach
no flags Details
Xorg.0.log (48.21 KB, text/plain)
2014-05-21 07:28 UTC, Lucas Stach
no flags Details
xrandr before failure (8.15 KB, text/plain)
2014-05-21 07:28 UTC, Lucas Stach
no flags Details
xrandr after failure (11.48 KB, text/plain)
2014-05-21 07:29 UTC, Lucas Stach
no flags Details

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Description Lucas Stach 2014-05-20 21:24:02 UTC
Created attachment 99447 [details]
dmesg from failing machine

Plugging in an VGA monitor and trying to enable it results in black screen on both the internal laptop display as well as the external VGA monitor.

The graphics is dead after this, I have not found any way to restore the screen. However the machine is still responding to ssh and I was able to pick up an quite interesting dmesg snapshot.

If you need me to test patches or need any other information, just ping me.
Comment 1 Alex Deucher 2014-05-20 21:29:12 UTC
Please attach your xorg log and xrandr --verbose output.
Comment 2 Lucas Stach 2014-05-21 07:28:30 UTC
Created attachment 99473 [details]
Xorg.0.log
Comment 3 Lucas Stach 2014-05-21 07:28:53 UTC
Created attachment 99474 [details]
xrandr before failure
Comment 4 Lucas Stach 2014-05-21 07:29:11 UTC
Created attachment 99475 [details]
xrandr after failure
Comment 5 Lucas Stach 2014-05-21 07:30:23 UTC
I attached two xrandr outputs as running xrandr already triggers the problem. So one log before and after the failure happened.
Comment 6 Lucas Stach 2016-01-07 20:17:37 UTC
Coming back to this after a long time. Meanwhile the APU is a Richland based chip in the same laptop chassis. Behaviour stays the same.

What I found out is that VGA lights up if it is connected at boot up, but when GDM tries to switch modes the ATOMBIOS hang is encountered again. So it seems like disabling the encoder does not work properly and it's not coming back to life when trying to enable it again. I've tried to disable various parts of the encoder disable sequence, but didn't find anything that would make a difference.

I would be very glad if someone with some more clue about this than me could take a look at this. Do you need any more traces/registerdumps/infos?


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