Resolution problem with AMD Radeon 5450/6350 and Dell U3011

[Johan Mazel]

I finally found some documentation :
http://i.dell.com/sites/content/shared-content/data-sheets/en/Documents/optiplex-990-tech-guidebook-final-1-4.pdf.
In a short word, for this particular Dell model, Optiplex 990, HD6350
is stuck at 1920x1200. I need to upgrade to HD6450 if I want
2560x1600.
This is also the case for Optiplex 960 with an AMD HD 3450 (cf
https://www.dell.com/downloads/global/products/optix/en/desktop-optiplex-960-technical-guidebook-en.pdf).
This means that the guys building graphic card for Dell are
particularly careless/cheap. :/

I'll check the xrandr trick.
I already tried something similar: generating a modeline through
cvt/gft, add it and use xrandr to use it. However, the image was
completely messed up.

Johan

2012/10/31 Thomas Lübking <thomas.luebking at gmail.com>:
> On Dienstag, 30. Oktober 2012 16:14:32 CEST, Johan Mazel wrote:
>> 2012/10/31 Alex Deucher <alexdeucher at gmail.com>:
>>> On Tue, Oct 30, 2012 at 6:35 AM, Johan Mazel
>>>> Theoretically, the HD5450 is able to display the screen's native
>>>> resolution (2560x1600) according to
>>>> http://www.amd.com/us/products/desktop/graphics/ati-radeon-hd-3000/hd-3400/Pages/ati-radeon-hd-3400-specifications.aspx
>>>> provided that a dual-link DVI cable is used, which is the case.
>>>> Unfortunately, the biggest available resolution is 1600x1200 on Debian
>>>> Testing and 1920x1200 for Ubuntu 12.10.
>
>>> While the chip is cable of dual link, dual link is only available if
>>> the oem wired up a dual link DVI connector on your card.  If the oem
>>> used a single link DVI connector, you will be limited to single link
>>> DVI.  I suspect that is what's happening.
>>>
>>> Alex
>>
>> Are you sure that this would explain both problems (I mean with Debian
>> and Ubuntu) ?
>> One hypothesis might be that the package used by Ubuntu 12.10 fixes
>> the software problem present in Debian's package version while the
>> hardware problems remains...
>
> Single link is limited to 1600x1200 unless the entire chain supports reduced blanking, what bumps the limit to 1920x1200 (both at 60Hz)
> Support for latter is probably not correctly detected on the Debian system.
>
> You can use xrandr --newmode and --addmode and see what happens if you try to forcefully select 2560×1600 (but i'd add a "sleep 10; xrandr -s 1920x1200" because the screen will likely turn off - or the DVI link burns ;-)
>
> Also ensure the cable to actually support DL and is not broken (test on other system)
>
> Notice that DVI-D does *not* mean "Dual"-Link, but "Digital". You need the pins in the center:
> http://upload.wikimedia.org/wikipedia/commons/thumb/f/fb/DVI_Connector_Types.svg/1000px-DVI_Connector_Types.svg.png
>
> Cheers,
> Thomas