[Bug 59824] New: External DP monitor goes black during heavy display activity

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=59824

          Priority: medium
            Bug ID: 59824
          Assignee: intel-gfx-bugs at lists.freedesktop.org
           Summary: External DP monitor goes black during heavy display
                    activity
        QA Contact: intel-gfx-bugs at lists.freedesktop.org
          Severity: normal
    Classification: Unclassified
                OS: Linux (All)
          Reporter: jadamcze at utas.edu.au
          Hardware: x86-64 (AMD64)
            Status: NEW
           Version: unspecified
         Component: DRM/Intel
           Product: DRI

Dell XPS L702x laptop, xorg log reports "Integrated Graphics Chipset: Intel(R)
Sandybridge Mobile (GT2)"

Running a custom configured 3.7.3 based kernel, xf86-video-intel-2.20.18.

I'm running the internal LVDS screen at 1080p and a Dell 2713HM monitor at
2560x1440 connected via display port.

Both screens run fine when X starts, but at some point the external monitor
will go black. The system doesn't recognize it as being disconnected - no KDE
popup asking if I want to change the monitor config as happens when pulling the
DP or power on the monitor.

Sometimes it will return to life after a short amount of time, most of the time
it stays black indefinitely. A full power cycle of the monitor (pulling the
plug) will usually bring it back to life, as will unplugging and replugging the
DP cable.

The screen usually goes black while there's a high degree of display activity -
a video playing, moving large windows around the screen, looking around in
google streetview, heavy output in a large terminal window, etc. It doesn't
seem to matter which screen the activity is on.

It *seems* to be less likely if I run the external display at a lower
resolution.

There's nothing that coincides with the screen going black in dmesg or the xorg
log, even with drm.debug=0xe on the command line.

Testing using this patch:
diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 1492706..5e91242 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -2580,6 +2580,8 @@ intel_dp_hot_plug(struct intel_encoder *intel_encoder)
 {
        struct intel_dp *intel_dp = enc_to_intel_dp(&intel_encoder->base);

+       printk("hotplug interrupt for DP\n");
+
        intel_dp_check_link_status(intel_dp);
 }

there was no hotplug interrupt triggered when the screen goes black.

I've had no problems with this monitor under Windows 7 (gaming, videos, etc).

Earlier discussion regarding this issue may be found here:
http://lists.freedesktop.org/archives/intel-gfx/2013-January/023874.html

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