Messages in this thread | | | Date | Thu, 27 May 1999 09:03:15 -0400 | From | Mark Lord <> | Subject | Re: 2.2.9 probs (ide hd, quota, 128MB (+sort)) |
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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 > > - > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.rutgers.edu > Please read the FAQ at http://www.tux.org/lkml/
-- mlord@pobox.com
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