Re: [PATCH 2.6.22.y] ieee1394: revert "sbp2: enforce 32bit DMA mapping"

[Stefan Richter <stefanr@s5r6.in-berlin.de>]

Robert Hancock wrote:
> I would agree, though, that sbp2 isn't really the place for setting
> this, since the DMA mask is presently a property of the device, not of
> the user..

The mask that sbp2 set was because sbp2 has (in theory, not yet in
practice) a _narrower requirement on address ranges than the chip_ ---
hence it has (in theory) a narrower requirement on DMA mappings than the
ohci1394 driver has.

That's because sbp2 uses the controller in a special mode, as a bus
bridge.  It is the only user of that feature among the higher-level IEEE
1394 drivers.  No other IEEE 1394 application-layer software has this
requirement.

(Well, debugging and forensic tools rely on that mode too, notably
BenH's firescope, but this software runs remote, hence it's a different
beast from sbp2.)
-- 
Stefan Richter
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http://arcgraph.de/sr/