Re: Matrox G550, dual head, 1680x1050

[Petr Vandrovec <vandrove@vc.cvut.cz>]

Hans-Jürgen Koch wrote:
> Am Montag, 5. März 2007 05:59 schrieb Petr Vandrovec:
> 
>> Can you try setting vxres for second head from 1680 to 1696, or 1728?
>> Maybe X look at vxres and not at framebuffer line length (what fbset -i
>> reports for line length?)
>>
> 
> Here are more details:
> 
> 1.) I boot my kernel (vanilla 2.6.20.1) with the following parameters:
> 
> video=matroxfb:outputs:120,pixclock:7380,xres:1680,yres:1050,upper:32,
>                lower:4,left:32,right:224,hslen:136,vslen:4,depth:32
> 
> This initializes the primary head correctly. The second head is probably 
> wrong, because the monitor's on screen message complains about a non-ideal 
> resolution.

Second head always starts in 640x480/32bpp.  You have to use fbset to 
switch it to different mode, so matroxfb works fine as far as I can tell.

> As you can see, the second monitor fell back to VGA resolution, but the logs 
> tell that X thinks it successfully switched to 1680x1050. The KDE control 
> center reports the same. The image on the second monitor is distorted.

Because X (mga driver) was programming hardware...

> 4.) I then issue the following command:
> 
> $ fbset -fb /dev/fb1 -g 1680 1050 1696 1050 32 -t 7380 224 32 32 4 136 4
> 
> With that, the image on the second monitor immediately becomes clear, and I 
> have a fully working xinerama configuration then.

Yes, and this corrects X programming mistake.

> As far as I can see, fbset is the only way to initialize the second head 
> properly. Neither matroxfb nor mga do it correctly with 1680x1050.

Well, fbset == matroxfb, so I do not quite understand your complaint.
							Petr


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