ISA DMA demand mode (again)

[Pierre Ossman]

A few months ago I asked why the linux ISA DMA code is locked to use 
only single mode but I didn't get much of a response. Now this has move 
from a curiosity to a necessity for my driver so I'm asking again. Using 
single mode I get transfer rates of 300 kBps. With demand mode I get 
1500 kBps. So you see why I'd like to use demand mode.

Side note: If I tell the DMA controller to do single mode and the chip 
to do demand I get 480 kBps. I find it amazing that it works at all in 
this case.

I included the people who helped me with the wonderful world of ISA DMA 
(;)) the last time in the hope that you might have some insight into this.

Rgds
Pierre
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