Linux 3.4-rc4

[Alex Deucher]

On Fri, Apr 27, 2012 at 8:39 PM, Nick Bowler <nbowler at elliptictech.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.

Alex