Message-ID: <20120428153350.GA19561@elliptictech.com>
Date:	Sat, 28 Apr 2012 11:33:50 -0400
From:	Nick Bowler <nbowler@...iptictech.com>
To:	Alex Deucher <alexdeucher@...il.com>
Cc:	Ben Skeggs <skeggsb@...il.com>,
	Martin Peres <martin.peres@...ri.fr>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	dri-devel@...ts.freedesktop.org
Subject: Re: Linux 3.4-rc4

On 2012-04-28 02:19 -0400, Alex Deucher wrote:
> On Fri, Apr 27, 2012 at 8:39 PM, Nick Bowler <nbowler@...iptictech.com> wrote:
> > Hi Ben,
> >
> > On 2012-04-27 15:20 +1000, Ben Skeggs wrote:
> >> Does this patch help you at all?
> >>
> >> http://cgit.freedesktop.org/nouveau/linux-2.6/commit/?id=a3a285f17867f0018de798b5ee85731ec1268305
> >
> > Yes.  I cherry-picked this patch on top of Linus' master (3.4-rc4+) and
> > this appears to solve the "black screen on VGA" problem described in the
> > original report.  Thanks!
> >
> > Unfortunately, that's not the end of my VGA-related regressions. :(
> >
> > While tracking down the black screen issue, I've been having the monitor
> > directly connected to the video card the whole time, but now when I'm
> > connected through my KVM switch (an IOGear GCS1804), it appears that
> > something's going wrong with reading the EDID, because the available
> > modes are all screwed up (both console and X decide they want to drive
> > the display at 1024x768).  Here's the output of xrandr on 3.2.15:
> >
> >  % xrandr
> >  Screen 1: minimum 320 x 200, current 1600 x 1200, maximum 4096 x 4096
> >  VGA-1 connected 1600x1200+0+0 (normal left inverted right x axis y axis) 352mm x 264mm
> >     1600x1200      75.0*+   70.0     65.0     60.0
> >     1280x1024      85.0 +   75.0     60.0
> >     1920x1440      60.0
> >     1856x1392      60.0
> >     1792x1344      60.0
> >     1920x1200      74.9     59.9
> >     1680x1050      84.9     74.9     60.0
> >     1400x1050      85.0     74.9     60.0
> >     1440x900       84.8     75.0     59.9
> >     1280x960       85.0     60.0
> >     1360x768       60.0
> >     1280x800       84.9     74.9     59.8
> >     1152x864       75.0
> >     1280x768       84.8     74.9     59.9
> >     1024x768       85.0     75.1     75.0     70.1     60.0     43.5     43.5
> >     832x624        74.6
> >     800x600        85.1     72.2     75.0     60.3     56.2
> >     848x480        60.0
> >     640x480        85.0     75.0     72.8     72.8     66.7     60.0     59.9
> >     720x400        85.0     87.8     70.1
> >     640x400        85.1
> >     640x350        85.1
> >     320x200       165.1
> >
> > And on 3.4-rc4+ (with your patch cherry-picked):
> >
> >  % xrandr
> >  Screen 1: minimum 320 x 200, current 1024 x 768, maximum 4096 x 4096
> >  VGA-1 connected 1024x768+0+0 (normal left inverted right x axis y axis) 0mm x 0mm
> >     1024x768       60.0*
> >     800x600        60.3     56.2
> >     848x480        60.0
> >     640x480        59.9
> >     320x200       165.1
> >
> > Running xrandr on 3.4-rc4+ also causes the screen to go black for a
> > second when it does not on 3.2.15.  It also causes several messages of
> > the form
> >
> >  [drm] nouveau 0000:01:00.0: Load detected on output B
> >
> > to be logged.  Also, looking at /sys/class/drm/card0-VGA-1/edid I see
> > that it is empty on 3.4-rc4+ and it is correct on 3.2.15.  Things seem
> > to work OK when the KVM is not involved.
> 
> Were you ever able to fetch a EDID with the KVM involved?  KVMs are
> notorious for not connecting the ddc pins.

Yes, it works on 3.2.15 as described above.

Cheers,
-- 
Nick Bowler, Elliptic Technologies (http://www.elliptictech.com/)

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