Messages in this thread | | | Date | Fri, 7 Dec 2001 13:50:31 -0500 | From | Jay Estabrook <> | Subject | Re: IDE DMA on AXP & barriers |
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On Fri, Dec 07, 2001 at 06:02:14PM +0100, Kurt Garloff wrote: > > > > How do I recognize the broken PYXIS in software? (Except for waiting for > > > your hard disk to be corrupted?) > > > > Put the chip into PCI loopback mode, read some memory (crossing the > > page boundary) via direct PCI window and check for corruption - > > perhaps this will work. > > I guess the manual will tell me how to do that ...
You might be able to adapt/add to Richard's code that probes CIA/PYXIS to determine if workarounds (for other things :-) are needed.
> That's why I'm looking for something better ... > But on a generic kernel, we have to do a number of things, then: > * Detect PYXIS > * Set into PCI loopback > * Do the cross 8k DMA read > * Set flag if corruption > > (And even this test is not completely perfect, as only devices on the > primary PCI bus seem to be affected.)
Correct; if you put the problematic card/driver behind the bridge on MIATA (ie one of the 32-bit slots), the problems go away. No such luck on LX/SX, but they may have HW workarounds already implemented.
> > Jay, your opinion? Perhaps you have the info which systems are affected? > > ... and how they can be identified.
"Identification" may need to be done via "probe and see"... :-\
IIRC, there was only ever one rev of PYXIS, which has a number of problems.
The first MIATAs went out with (nearly) no fixes, except for the console cruft to prevent "unknown" cards from being placed in the 64-bit slots (unkown cards == unknown drivers == possibly susceptible to the 8K boundary DMA error).
LX and SX introduced off-chip PYXIS fixes, which fixed at least the 8K boundary DMA problem, and some others, but NOT all, most notably the PCI READ prefetch.
Late MIATAs, aka MIATA-GL, have off-chip logic that fix ALL the PYXIS problems, AFAIK. These are distinguished from the earlier model by the presence of a QLogic ISP-1040C(?) SCSI chip built into the motherboard.
--Jay++
----------------------------------------------------------------------------- Jay A Estabrook Alpha Engineering - LINUX Project Compaq Computer Corp. - MRO1-2/K15 (508) 467-2080 200 Forest Street, Marlboro MA 01752 Jay.Estabrook@compaq.com ----------------------------------------------------------------------------- - 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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