Bug 61642

Summary: [uxa] LVDS doesn't come back after "xrandr --output LVDS1 --off; xrandr --output LVDS1 --auto"
Product: xorg Reporter: Carl Worth <cworth>
Component: Driver/intelAssignee: Chris Wilson <chris>
Status: RESOLVED FIXED QA Contact: Intel GFX Bugs mailing list <intel-gfx-bugs>
Severity: normal    
Priority: medium CC: daniel, eich, imre.deak, phil
Version: git   
Hardware: Other   
OS: All   
Whiteboard:
i915 platform: i915 features:
Attachments:
Description Flags
dmesg log of the 4 operations with drm.debug=0xe as requested none

Description Carl Worth 2013-03-01 00:41:20 UTC 
I found this behavior consistnent with kernels 3.6.11, 3.8.0, and 3.8.1

With an external monitor plugged into my Lenovo x220 I can turn the LVDS
off with:

	xrandr --output LVDS1 --off

And this works as expected, (LVDS display turns off). But when I try
to turn it on again with:

	xrandr --output LVDS1 --auto

nothing comes on. This is in spite of the fact that xrandr does report
that the LVDS output is on at this point:

	$ xrandr | grep -A1 LVDS1
	LVDS1 connected 1366x768+0+0 (normal left inverted right x axis y axis) 277mm x 156mm
	   1366x768       60.0*+

At this point things appear entirely off, (it does not appear to be a
case where just the backlight is off, for example).

Note that I can cause the LVDS display to turn on by issuing a modeset,
such as:

	xrandr --output LVDS1 --mode 1024x768

At this point my display turns on again, and then finally I can get
the mode I want back with:

	xrandr --output LVDS1 --auto

Please let me know if you need any further information, and I'll be
happy to supply it.

Thanks,

-Carl
Comment 1 Jani Nikula 2013-03-01 07:32:42 UTC 
(In reply to comment #0)
> With an external monitor plugged into my Lenovo x220 I can turn the LVDS
> off with:

Just to confirm, is the external monitor required to reproduce this? (FWIW I can't reproduce this on an x220T with/without an external monitor.)

> Please let me know if you need any further information, and I'll be
> happy to supply it.

It smells a bit like a kernel issue to me. Please provide a dmesg with drm.debug=0xe module parameter, preferably running the 3.8 kernel, exhibiting the xrandr --off, --auto, --mode, --auto sequence.
Comment 2 Chris Wilson 2013-03-01 08:40:20 UTC 
In the past this has been true to false tracking of the DPMS state on the connector (and its multiple reincarnations like intel_connector->active).
Comment 3 Carl Worth 2013-03-01 21:07:48 UTC 
(In reply to comment #1)
> Just to confirm, is the external monitor required to reproduce this? (FWIW I
> can't reproduce this on an x220T with/without an external monitor.)

I hadn't tested this previously, but apparently yes.

I just verified that I could not reproduce the bug without the
external monitor, but then immediately after adding the monitor (via
DisplayPort) the same commands showed the bug.

> It smells a bit like a kernel issue to me. Please provide a dmesg with
> drm.debug=0xe module parameter, preferably running the 3.8 kernel,
> exhibiting the xrandr --off, --auto, --mode, --auto sequence.

I'll follow up with that output shortly.

Thanks,

-Carl
Comment 4 Carl Worth 2013-03-01 21:22:44 UTC 
Created attachment 75758 [details]
dmesg log of the 4 operations with drm.debug=0xe as requested

Here's the dmesg log as requested.

I inserted markers into the log of the form:

    cworth: xrandr --output LVDS1 --off

So that you can grep for "cworth" to find the beginning of each command.

Good luck. And again, let me know what else you might need from me.

-Carl
Comment 5 Chris Wilson 2013-03-02 11:16:25 UTC 
Actually doesn't seem to be a kernel bug at all:

LVDS --off: no setcrtc to disable the LVDS, just backlight is turned off
LVDS --auto: setcrtc is called, but is a no-op
LVDS --mode 1024x768: reconfiguration detected, modeset performed

userspace *should* be disabling the output rather than turning it off, but the second failure looks like userspace is then assuming that it gets turned back on by auto.
Comment 6 Chris Wilson 2013-05-03 10:55:38 UTC 
*** Bug 64178 has been marked as a duplicate of this bug. ***
Comment 7 Phil Dibowitz 2013-05-21 15:31:10 UTC 
FWIW, I see the same behavior on my x220.
Comment 8 Chris Wilson 2013-06-07 18:19:08 UTC 
Praise be, Daniel is fixing UXA bugs in the kernel.

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