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SubjectRe: 2.2.9 probs (ide hd, quota, 128MB (+sort))
Andre,

This explanation is completely bogus, at least for this particular
problem.

We do NOT use DMA for the "IDENTIFY_DRIVE" command.
We do NOT use DMA for the "IDENTIFY_DRIVE" command.
We do NOT use DMA for the "IDENTIFY_DRIVE" command.

-ml


"Andre M. Hedrick" wrote:
>
> On Mon, 24 May 1999, Guest section DW wrote:
>
> >
> > > The ide-dma code does/can not enable UDMA-3/4; therefore, it is not used.
> >
> > Maybe I should not ask since I do not know about these things,
> > but you said that this was a ATA/66 problem. How precisely is
>
> I do not know yet, but I will ramble about what I have observed and tested.
>
> > this caused? And what is the problem, if disabling DMA does not cure it?
>
> There appears to be an ugly transistion period in the standard.
>
> There are chipsets that claim to ATA-66 compliant....
> Translation ::
>
> We can detect/trigger but not make use of UDMA-3/4.
> Known offenders are the ALI1543 AGP-PRO and VIA???? AGP-PRO.
> This is different from the ALI1543 TX-PRO and VIA82c568 TX-PRO.
> It appears through imperical tests that the evolution of the TX-PRO to the
> AGP-PRO as gone very wrong. This may not have any thing to do with
> Intel's BX chipset, but something is very bad. There appears to be no bit
> sensing of capablity in all directions.
>
> I am now in agreement with Mark's suggestion to leave this alone for a
> while. The problem is that I need to still figure out how to speed break
> drive chipset combinations. Many componets are over-promising and
> under-delivering. The short is that BIOSes need to be able to throttle
> back the drives if they can not perform the IO, but they don't.
>
> Maybe if this guy disables UDMA and forces DMA mode 2 in the BIOS, we may
> be able to get a correct drive table report. A crippled drive is better
> than one that is unusable.
>
> There are drives that claim to ATA-66 compliant....
> Translation ::
>
> We can fake the detection with our interface, but we can not do it.
> Reported offender is the Fujitsu MPDxxxx drives, but this was only in
> combination with the AGP-PRO boards. I tested this on the Ultra66 and it
> correctly reported ATA-33 and no goofballing/fudging.
>
> As for my answers that are confusing, so is the standard.
>
> Everyone is over selling what they can do, and under delivering.
>
> ATA-66 is only verified successful on the Promise Ultra66 chipset.
> There a only a few drives that can correctly report, handle, and perform
> ATA-66.
>
> WDC AC29100D FwRev=J74OA30K real good fastest yet at ~17MB/sec
> WDC AC310200R FwRev=17.01J17 a brick at ~13MB/sec
> IBM-DJNA-371800 FwRev=J78OA30K speed untested
>
> Note that WDAC3xxxxxR and/or firmware 17.01J17 is a kludge drive that
> technically works, but is slower than many ATA-33 drives.
>
> Andre Hedrick
> The Linux IDE guy
>
> -
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