Blank screen after updating to Kernel 3.16 with Radeon HD4250 and DVI

[Markus Gaugusch]

On Nov 10, Alex Deucher <alexdeucher at gmail.com> wrote:

> On Fri, Nov 7, 2014 at 3:32 PM, Markus Gaugusch <markus at gaugusch.at> wrote:
>> Hi,
>>
>> I hope you can help me ...
>>
>> After upgrading my system to openSUSE 13.2 I experienced very bad behaviour
>> - my screen started to go blank during boot, returned again, turned black
>> again and kept black. Sometimes it returned for a short while and went black
>> again.
>>
>> I was able to get a stable picture by using VGA instead of DVI connection or
>> by using the old kernel from openSUSE 13.1 (linux 3.11.6). So it is
>> definitely a kernel-only problem.
>> I can also get a stable DVI connection with the new kernel if I connect BOTH
>> cables (VGA+DVI)! I have set my screen to "mirroring", so I have the same
>> picture via VGA and DVI now. If I disconnect VGA, it still works, but only
>> until the moment that I run "xrandr". As soon as I reconnect VGA, DVI is
>> stable again.
>>
>
> Sounds like a pll problem.  If you can bisect, that would be great,
> but in the interim, I'd suggest trying the patches on this bug:
> https://bugzilla.kernel.org/show_bug.cgi?id=83461
Looks promising, I'll try when I'm at the machine again.

>
> Do you have problems with any any other modes?  E.g.,
>
> xrandr --output DVI-0 --mode 1680x1050

Hi Alex!
By pure luck I tried this yesterday and 1680x1050 works fine on DVI ... 
the funny thing is that if I switch to a VT console and then back, I get a 
picture for a very short time, then black again. The monitor also reacts 
strange - I can no longer switch it to VGA, it is just blank and black 
(but with signal, though no OSD).


> Alex

Markus