[En-Nut-Discussion] Remote DMA for RTL8019AS

[Harald Kipp]

Michel,

At 22:27 05.01.2004 -0500, you wrote:
>What are the purpose for the remote DMA count registers (RBCR1:RBCR0) for 
>the RealTek part ?
>
>I assume that when the value in these DMA count registers reaches 0:0, 
>then the DMA address registers are not incremented any more. Further read 
>attempts would only read the value in the last DMA address. Is this correct ?

I think, these counters are required by the inner
logic of the controller. I never checked, what would
happen if you set them to something different than
the number of bytes to read. But from experience the
RTL8019 behaves very unreliable if you do not exactly
follow the correct path.

I don't think, that it increases performance noticable.
The read and write loops are the most important parts.
Either use assembly routines or take care about the
compiler's resulting code. Sometimes the compiler
produces better code, if you put the loop into a
separate routine. Small routines are better optimized.

Harald