Subject: Re: needs MI wdc changes to support macppc's wdc
To: Izumi Tsutsui <firstname.lastname@example.org>
From: Ignatios Souvatzis <email@example.com>
Date: 11/04/1998 11:24:17
On Wed, Nov 04, 1998 at 07:16:40PM +0900, Izumi Tsutsui wrote:
> firstname.lastname@example.org wrote:
> > On Tue, Nov 03, 1998 at 11:15:09AM -0800, Jason Thorpe wrote:
> > > I don't think it will be much overhead. For multi-pio, the address will
> > > be computed only once. I think the reg map in the wdc driver is the right
> > > way to go.
> > Yes, but ports as the Amiga that need variable strides in bus_space anyway
> > will get the double overhead.
> Currently, my patch is using the reg map array
> only if `WDC_NONCONTIG_REG' is defined.
> Otherwise the array offset is used as register address offset.
> There are following defines in /sys/dev/ic/wdcvar.h:
> #if defined(macppc)
> # define WDC_NONCONTIG_REG
> #ifdef WDC_NONCONTIG_REG
> #define wdcregoff(chp, a) (chp)->wdc->reg_offset[a]
> #define wdcregoff(chp, a) (a)
> This implementation avoids overheads on archs which have
> only contiguous offsets, but I'm not sure whether these
> defines are appropriate.
This will work, of course. However, I thought all the bus_space_xxx stuff
was about is to avoid such ifdefs in machine independent drivers...