Re: CPU Initiated DMA

["Steven J. Magnani" <steve@digidescorp.com>]

On Sat, 2011-01-08 at 12:16 -0600, Robert Hancock wrote:
> On 01/07/2011 02:55 PM, Nikolaus Rath wrote:
> > Hello,
> >
> > I want to write a driver for a rather dumb PCI card, which cannot become
> > bus master itself. Is it possible to use a DMA controller on the
> > mainboard to still transfer data to the card without occupying the CPU?
> >
> > (I believe this is the way DMA used to work on ISA cards, but do recent
> > x86 systems still have a DMA controller for the CPU?)
> 
> The legacy ISA DMA controller worked like that, but you can't use that 
> with PCI devices. Essentially there is no way to do this, barring 
> perhaps some wierd platform specific feature.

I believe a DMA Engine would work here - platform-specific, yes, but I
wouldn't call it "wierd"  :)

See Documentation/dmaengine.txt.

Regards,
------------------------------------------------------------------------
 Steven J. Magnani               "I claim this network for MARS!
 www.digidescorp.com              Earthling, return my space modulator!"

 #include <standard.disclaimer>