Bug 39027 - [evergreen] Monitor fails to come back after unplug and replug (recent regression)
Summary: [evergreen] Monitor fails to come back after unplug and replug (recent regres...
Alias: None
Product: DRI
Classification: Unclassified
Component: DRM/Radeon (show other bugs)
Version: unspecified
Hardware: x86-64 (AMD64) Linux (All)
: medium normal
Assignee: Default DRI bug account
QA Contact:
Depends on:
Reported: 2011-07-07 01:54 UTC by Thomas Lindroth
Modified: 2011-07-31 15:07 UTC (History)
0 users

See Also:
i915 platform:
i915 features:

fix (1.18 KB, patch)
2011-07-11 07:48 UTC, Alex Deucher
no flags Details | Splinter Review

Description Thomas Lindroth 2011-07-07 01:54:51 UTC
I use an xrandr desktop with two monitors connected to hdmi and vga. If I unplug the hdmi monitor both monitors goes blank (regression since a few weeks back). When I plug it back in the hdmi monitor comes back but the vga monitors stays blank. Switching to vt1 and back to vt7 restores both monitors. dmesg and Xorg.0.log doesn't show anything out of the ordinary.

Using an Evergreen cedar card with xorg-server-1.10.2 and linus kernel, mesa, xf86-video-ati, libdrm compiled from git as of today from gentoo live ebuild.
Comment 1 Thomas Lindroth 2011-07-07 02:50:21 UTC
It is a kernel regression. A bisect on the drivers/gpu folder resulted in the following likely candidate.

commit 1e85e1d07b9255bd52c557f1a77fb72ccfacaf1c
Author: Alex Deucher <alexdeucher@gmail.com>
Date:   Fri May 20 04:34:29 2011 -0400

    drm/radeon/kms: simplify hotplug handler logic
    In the hotplug handler, just use the drm dpms functions.
    If the monitor is plugged in, turn it on, if it's not,
    turn it off.  This also reduces power usage by turning
    off the encoder and crtc when the monitor is unplugged.
    Signed-off-by: Alex Deucher <alexdeucher@gmail.com>
    Signed-off-by: Dave Airlie <airlied@redhat.com>
Comment 2 Alex Deucher 2011-07-11 07:48:50 UTC
Created attachment 48977 [details] [review]

This patch should fix it.
Comment 3 Thomas Lindroth 2011-07-11 10:38:01 UTC
The provided patch fixed the problem.
Comment 4 Florian Mickler 2011-07-31 11:45:30 UTC
A patch referencing this bug report has been merged in Linux v3.0:

commit cbac9543281f8e813f3ca9186c963a9b55136e93
Author: Alex Deucher <alexdeucher@gmail.com>
Date:   Mon Jul 11 14:49:28 2011 +0000

    drm/radeon/kms: fix regression in hotplug

Use of freedesktop.org services, including Bugzilla, is subject to our Code of Conduct. How we collect and use information is described in our Privacy Policy.