Subject: Re: mc* performance patch
To: Tim Kelly <hockey@dialectronics.com>
From: Allen Briggs <briggs@netbsd.org>
List: port-macppc
Date: 01/14/2005 23:20:29
On Fri, Jan 14, 2005 at 10:11:06PM -0600, Dave Huang wrote:
> Which bus does mc attach to on macppc?

obio

> There are plenty of PCI NIC drivers that use bus_dma, but I have no
> idea if those would be a good example for an obio-attached device.

The bus match and attachment should be independent of the bus_dma
usage in the driver.  If you look at the AMD "Lance" ethernet
(if_le), there are a slew of bus attachments (sbus, obio, pci, isa,
pcmcia, qbus, vme, turbochannel, etc.), but they all "just work"
with src/sys/dev/ic/am7990.c.

I haven't really thought about it or looked again at how the dbdma
works, but I think that can/should be hidden in the bus_dma
implementation for obio.  I'm not sure, though.

I think dbdma is more powerful than what we're using it for.  We
might be able to eke some more performance out of the system by
using it better, but it's not clear that that fits our device model
very well.

-allen

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