Messages in this thread | | | Date | Tue, 07 Aug 2007 00:59:53 +0200 | From | Stefan Richter <> | Subject | Re: [PATCH 2.6.22.y] ieee1394: revert "sbp2: enforce 32bit DMA mapping" |
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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 -=====-=-=== =--- --=== http://arcgraph.de/sr/ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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