It's pretty easy to add. you just set the entity as shared and create a second pScrn for the second head. In the XF86Config file you then create two device entries, one for each head and use "Screen 0" and "Screen 1" to differentiate them. Internally to just add somehting like Bool IsSecondary or IsCRTC2 to each screen info rec so that when each head is inited it will take the approprate code path. then you divide the videoram in two and set up modes on each head. Use the radeon or mga drivers for reference. They support multihead quite well. I tried to add crtc2 support to the savage driver last year, but I was never able to get the databooks for VIA/S3 so I could never get it to work. Everything was in place and working expect the mode stuff. For some reason I could never get writes to work on the crtc2 regs. I suspect I also had to touch some bits somewhere to change the DAC for crtc2, but I don't know which bits. here's what I had for reference:
http://www.botchco.com/alex/new-savage/html/ It shouldn't be too hard to finish, I just never had docs... I did the same thing for r128 based hardware, but once again, without databooks, I had little luck. I thought it would be similar to radeon, but unfortunately, it's not. For what it's worth the virge mx has two crtcs as well. I kinda gave up on savage and started working on mergedfb support for radeon (http://bugs.xfree86.org/show_bug.cgi?id=276). adding mergedfb support is pretty easy once you get regular pScrn based multi-head working. Alex --- Tim Roberts <[EMAIL PROTECTED]> wrote: > On Wed, 13 Aug 2003 06:36:04 -0700 (PDT), Alex Deucher wrote: > > > >some mach64 mobility chips had a second crtc that was never > supported. > >same thing with rage 128. > > Same thing with most of the Savage chips, because I couldn't see an > easy way to > support it. Is this "double-headed" feature now common enough that > there > should be some kind of architectural support for it? I'm not sure > what that > support would look like, but implementing it today seems an awful lot > like a > hack. > > -- > - Tim Roberts, [EMAIL PROTECTED] > Providenza & Boekelheide, Inc. > __________________________________ Do you Yahoo!? Yahoo! SiteBuilder - Free, easy-to-use web site design software http://sitebuilder.yahoo.com _______________________________________________ Devel mailing list [EMAIL PROTECTED] http://XFree86.Org/mailman/listinfo/devel
