On Sun, Dec 16, 2001 at 07:47:55PM -0000, David Laight wrote:
> There are definitely problems with DMA on the 646.  I didn't (quite)
> get involved in trying to fix (improve) the solaris driver...
> 
> I saw a data sheet which implied that there is a shared data path for the
> two channels.
> This means that you have problems if you have more than one disk per
> controller.  We had 4 controllers with a disk each - until someone
> decided sound and integrated video were more important.
> With 2 discs per controller (master on each channel) you get horrid
> read errors...

Yes, with the cmd chips (at last up to the 646) you can't issue conurent
requests to both channels. NetBSD uses a single queue of commands for
all cmd chips. Maybe the 648 and 649 have really separate channels, but
I don't have the hardware to test.

--
Manuel Bouyer <bouyer@antioche.eu.org>
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