Re: working multihead

[Petr V. <VAN...@vc...>]

On 24 Jan 01 at 21:21, Brad Midgley wrote:
> > If it does not work with dualhead G400, then he did something wrong:
> 
> i wasn't aware that framebuffer could provide access to both screens on a g400. 
> 
> i guess i was basing that on the fact that the matrox-endorsed dual-monitor support for x is
> provided by a closed-source xf4 module -- fb is not used in that scenario.

Yes. It is really unfortunate that G400 driver in XFree is somewhere in
DGA broken - if you run it with 'UseFBDev' on G450, normal X works, but
DGA access (vmware) still accesses ramdac directly, killing monitor (200kHz
horizontal, 200 Hz vertical) and dies in endless loop (PLL not synced) :-(
Matrox driver works fine with UseFBDev.

> that's great we have fb driving two outputs on one card. i looked into doing that for the ati
> ltpro a while back. back then there was no clear way to set two framebuffers to be mirrored
> (taking advantage of the chip's native ability to mirror). mirroring is the main motivation for
> proper ltpro support.

It is only mode I do not support, as it would require too many changes to
my code, and also API is not clear yet... You always want independent
left/right/hslen/upper/lower/vslen/pixclock (and eventually xzoom/yzoom). 
Sometime you want independent xres/yres/xoffset/yoffset, but sometime you 
want them same for both CRTCs... And sometime you do not have enough pixclock
sources, so sometime secondary pixclock can be only few exact values
(33MHz (PCI), 66MHz (AGP), 150MHz (memory clocks), XXX (first head clocks)).
                                                Best regards,
                                                        Petr Vandrovec
                                                        van...@vc...