Bug 39882 - Regression: Plugging in a HDMI connector makes the LCD of X120e go dark
Summary: Regression: Plugging in a HDMI connector makes the LCD of X120e go dark
Alias: None
Product: DRI
Classification: Unclassified
Component: DRM/Radeon (show other bugs)
Version: XOrg git
Hardware: x86-64 (AMD64) Linux (All)
: medium normal
Assignee: Default DRI bug account
QA Contact:
Depends on:
Reported: 2011-08-06 06:27 UTC by gottfried.haider
Modified: 2011-08-23 13:18 UTC (History)
1 user (show)

See Also:
i915 platform:
i915 features:

lspci of Lenovo X120e (1.95 KB, application/octet-stream)
2011-08-06 06:28 UTC, gottfried.haider
no flags Details
dmesg (nothing interesting after HDMI insertion) (64.67 KB, application/octet-stream)
2011-08-06 06:31 UTC, gottfried.haider
no flags Details
Xorg.log (HDMI insertion happened just before 906.688) (48.31 KB, application/x-trash)
2011-08-06 06:33 UTC, gottfried.haider
no flags Details
fix (3.87 KB, patch)
2011-08-13 10:28 UTC, Alex Deucher
no flags Details | Splinter Review

Description gottfried.haider 2011-08-06 06:27:10 UTC
When I plug in my external TFT monitor while my X120e is in use, the laptop's internal LCD immediately goes dark - yet I don't have a picture on the TFT.

I first noticed this with kernel 3.0.0, this is fully reproducible also on 3.0.1. Since I did not remember this happening before, I tested with an older kernel (Ubuntu's 2.6.38, but should not make a difference), and indeed: with 2.6.38 the internal LCD stays on (which is the expected behavior).

The TFT is connected via a HDMI-to-DVI cable. Userspace is Xubuntu 11.04 with xorg-edgers PPA.

At a first glance, I do not see anything interesting in either dmesg or Xorg.log when this happens. Note: the machine does not hang, since I can still (blindly) launch a terminal and make the machine restart - for which I briefly get a picture on the LCD again after XOrg shutdown.

I am attaching lspci and a dmesg/Xorg.log below - please let me know if I can help with anything else (I can easily test kernel patches).
Comment 1 gottfried.haider 2011-08-06 06:28:25 UTC
Created attachment 49992 [details]
lspci of Lenovo X120e
Comment 2 gottfried.haider 2011-08-06 06:31:57 UTC
Created attachment 49993 [details]
dmesg (nothing interesting after HDMI insertion)
Comment 3 gottfried.haider 2011-08-06 06:33:29 UTC
Created attachment 49994 [details]
Xorg.log (HDMI insertion happened just before 906.688)
Comment 4 Alex Deucher 2011-08-06 07:27:46 UTC
Can you bisect?  If I had to guess, it's probably one of the display rework patches added in 3.0.  Does a VT switch help?
Comment 5 gottfried.haider 2011-08-06 12:26:19 UTC
Sorry, I tried bisecting, but defconfig does not boot here.. and my normal config takes ages for a full rebuild.
Comment 6 gottfried.haider 2011-08-10 17:03:12 UTC
Regarding VT switching: When I press Ctrl+Alt+F1 after plugging in I do get a picture again on the internal LCD.. when I then press Ctrl+Alt+F7 I am even properly back in X.

Comment 7 Alex Deucher 2011-08-12 14:45:34 UTC
It's a bad interaction between modesetting and hotplug.  I'm working on a patch.
Comment 8 Alex Deucher 2011-08-13 10:28:00 UTC
Created attachment 50185 [details] [review]

This patch fixes the issue.
Comment 9 Alex Deucher 2011-08-17 11:21:36 UTC
The patch works for me.  If you still have issues, please reopen.
Comment 10 gottfried.haider 2011-08-19 18:31:55 UTC
Sorry that it took a bit long, but I confirm this as being fixed. (Thanks!)
Comment 11 Florian Mickler 2011-08-23 13:18:55 UTC
A patch referencing this bug report has been merged in Linux v3.1-rc3:

commit d5811e8731213f80c80d89e980505052f16aca1c
Author: Alex Deucher <alexander.deucher@amd.com>
Date:   Sat Aug 13 13:36:13 2011 -0400

    drm/radeon/kms: don't try to be smart in the hpd handler

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