[MPlayer-dev-eng] MGA Xv sux...

[D Richard Felker III]

On Sat, Jul 20, 2002 at 01:54:11PM +0200, Arpi wrote:
> Hi,
> 
> > On Sat, Jul 20, 2002 at 12:38:00AM +0200, Arpi wrote:
> > > Maybe it's just really impossible to allocate SHM memory in video ram?
> > > Or just the boy designing it thought that every card can do DMA transfers
> > > easily? (maybe he's right?)
> > 
> > That is a very good point -- I think it would be pretty easy to add
> easy????????
> nope. it requires specially allocated linear memory area, programming both
> the MB and vga dma controller, set up busmastering etc..
> Nick tried to implement it for radeon in vidix, using kernel module helper,
> but afaik no success.
> Peter Surda did it for rage128 Xv driver spending about half year with DRM
> hacking... i wouldn't call it easy.
> ah, and nvidia's binary shit also uses dma in Xv.
> 
> > dma transfer support tp mga_vid/vidix/fbdev. I think SDL (which is
> i doubt it. sdl is an userspace lib... dma requires kernel space and
> deep knowledge of chip details. maybe directfb does it, i remember reading
> it somewhere, but i'm not sure.

Oh, I bet SDL just does accelerated video-to-video blits. That would
be a lot easier and wouldn't need dma. My fault for being stupid and
not thinking.

Anyway the Matrox tech docs *do* seem to provide enough information
for anyone interested in implementing dma on mga_vid. Programming the
card for it doesn't seem to be that hard -- but of course like you
said all the host-side stuff and kernel hacking required is likely to
be hell.

Rich