Messages in this thread | | | Date | Fri, 7 Dec 2001 17:03:41 +0300 | From | Ivan Kokshaysky <> | Subject | Re: IDE DMA on AXP & barriers |
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On Fri, Dec 07, 2001 at 01:25:05PM +0100, Kurt Garloff wrote: > So I wonder where the bug actually is. Somewhere in hardware; but I wonder > whether the CMD646 or the 2117x (PYXIS/CIA) is to blame. The QLogicISP seems > to happily do BM-DMA, so I'd point to the CMD646.
Hmm, it seems to be a pyxis bug; the hardware workaround exists, but I guess that it might be not implemented properly on early miatas. This also explains why I don't have that problem on lx164 and sx164. >From pyxis manual: "A.1 Read Page Problem PCI DMA reads that attempt to cross 8K page boundaries cause data corruption problems. A fix has been implemented with an Altera 7032 and two Pericom PI5C3400 bus switches and a diode."
> OTOH, the QLogic sits on > the 2nd PCI bus (32bit), which could make a difference as well.
Certainly - the 2nd bus is behind PCI-PCI bridge.
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