Re: Problems w/Sandy Bridge & 27" monitor

[Daniel Vetter <daniel@ffwll.ch>]

On Mon, Aug 27, 2012 at 03:30:26PM -0400, Chun-Yu Shei wrote:
> On 08/27/2012 03:08 PM, Daniel Vetter wrote:
> >On Mon, Aug 27, 2012 at 02:47:58PM -0400, Chun-Yu Shei wrote:
> >>On 8/15/2012 6:47 PM, Daniel Vetter wrote:
> >>>On Wed, Aug 15, 2012 at 06:38:10PM -0400, Chun-Yu Shei wrote:
> >>>>Hi,
> >>>>
> >>>>I recently upgraded to a 27" monitor (2560x1440) from a 23" one
> >>>>(1920x1080), and had to switch to Windows because the new monitor is
> >>>>unusable in Linux.  Today, about a month later, I decided to give
> >>>>Linux another try, since there have been several updates to the
> >>>>Intel graphics driver since then.
> >>>>
> >>>>Unfortunately, it seems that it's still unusable with
> >>>>xf86-video-intel 2.20.3 -- after a little while, the video signal to
> >>>>the 27" monitor completely stops, and it goes into power saving
> >>>>mode.  I'm running dual monitors with the old 23", and that one
> >>>>continues running fine when this happens.  This happens on my
> >>>>ThinkPad X220 (i5-2540M).  The 27" is connected via DisplayPort, and
> >>>>the 23" via DVI.  SNA is enabled, if it makes any difference (I
> >>>>haven't tried turning it off, but I probably should).  This is the
> >>>>biggest problem I'm facing when it comes to Linux support.
> >>>>
> >>>>I also gave the new "TearFree" option a try, and while it does a
> >>>>great job of eliminating tearing, it makes the two monitors become
> >>>>mirrors of each other for some reason.  If I take a screenshot with
> >>>>the GNOME tool, the screenshot comes out as expected (unmirrored),
> >>>>but the video output on the two monitors is mirrored in reality.
> >>>>Disabling "TearFree" fixes this.
> >>>>
> >>>>Also, when I'm using the ThinkPad's built-in display, it sometimes
> >>>>turns off for no apparent reason, although it's not too big of a
> >>>>deal since a suspend/resume cycle seems to fix things (and I haven't
> >>>>used 2.20.3 long enough to experience this yet).
> >>>>
> >>>>Any ideas/things I can do to help track these issues down?
> >>>
> >>>For the screen blanking issues, the kernel is the important part. Please
> >>>boot with drm.debug=0xe added to your kernel bootline and grab the full
> >>>dmesg.
> >>>-Daniel
> >>>
> >>
> >>OK, I finally got around to doing this... I just upgraded to the
> >>3.5.3 kernel and xf86-video-intel 2.20.5 as well.
> >>
> >>Here's the initial dmesg upon bootup: http://pastebin.com/41F2AA0f
> >>
> >>And here's the dmesg right after the 27" goes blank:
> >>http://pastebin.com/3CTRETQ4 (not completely blank, though... there
> >>are a few lines at the very left & top edge of the display)
> >>
> >>A few seconds later, the display came back, and here's the dmesg
> >>right after that: http://pastebin.com/9mdfY5P1
> >
> >Hm, there's nothing really interesting with that screen going on ... Also,
> >3.5.3 is  up-to-date with all recent DP fixes. One thing that could be is
> >that this is another version of our fdi link training woes on ivb.
> >
> >To check for that, can you please run your 27" screen at a much lower
> >resolution? If it still blanks out, it's a different issue.
> >
> >Thanks, Daniel
> >
> 
> Seems to be working perfectly at 1600x900 (btw, I'm on Sandy Bridge,
> not ivb).

Hm ... I'm running low on ideas to try out then. Can you please file a bug
report on bugs.freedesktop.org against drm/intel?

Thanks, Daniel
-- 
Daniel Vetter
Mail: daniel@ffwll.ch
Mobile: +41 (0)79 365 57 48