At 5:15 AM -0400 4/8/02, Mike Haertel wrote:

>Is anybody already working on this?  If not, I would
>like to take a crack at it.

I am. I already have code which does the DMA into a bounce-buffer. However,
this doesn't offer much of a speed up because of the extra bcopy. What I'd
like to do is to get the bus_dma() infrastructure in place and have the dma
engine read/write directly into the destination memory.

Looking around, I can see that we can pretty much copy the bus_dma()
routines from the NeXT port. The next step is to make a dma engine device
that can take a list of contiguous regions in the form of a bus_map and do
a bunch of dmas. This is slightly different than the bounce-buffer driver
because the bounce-buffer driver uses the SCSI chip's interrupt to see if
the DMA is complete. What I need to do is to track down the SCSI DMA
interrupt. Finding it shouldn't be too hard, it's probably with the rest of
the PSC interrupts.

Anyway, that's the deal. I just need a few days to work on it. Of course,
that's the hardest part of all! :-)


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 Michael Zucca - mrz5149@acm.org
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 "I'm too old to use Emacs." -- Rod MacDonald
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