[MPlayer-dev-eng] DMA or not DMA

[D Richard Felker III]

On Wed, Nov 24, 2004 at 10:28:24AM +0100, Attila Kinali wrote:
> Hi,
> 
> In a discussion on the open-graphics mailinglist the question DMA 
> came up. Basicaly why players like MPlayer don't use DMA but do 
> instead a mem2pci/agp copy.
> 
> >From the discussion, i musst say, that i don't see a real
> problem to use DMA and that it would gain some performance.
> 
> If DMA with MPlayer is just a matter of setting up a DMA-channel,
> then i will try to patch mga_vid to use it instead (but that
> wont be before the christmas break and after the 2.6 port is finished)
> 
> Do you see any problems with DMA or would it be just a straight
> forward implement and forget thing ?

imo the biggest problem is that you have to have some way of knowing
when the dma is finished so you don't start writing a new frame to the
buffer before then.

btw is there any advantage of doing slice-by-slice dma? or would dma
all be done at the end of the frame?

rich