Re: Problems w/Sandy Bridge & 27" monitor

[Chun-Yu Shei <cshei@cs.indiana.edu>]

On 08/27/2012 03:32 PM, Daniel Vetter wrote:
> 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
>

Will do... I did a little more experimenting, and things seem to be fine 
at 1920x1440, but 2048x1152 starts to show the same screen blanking problem.

Chun-Yu