Messages in this thread | | | Date | Mon, 12 Mar 2001 11:33:54 -0800 (PST) | From | Andre Hedrick <> | Subject | Re: Linux 2.4.2ac12 (vt82c686 info) |
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Daniela,
Great to hear from you again my dear! ;-)
On Fri, 9 Mar 2001, Vojtech Pavlik wrote:
> On Fri, Mar 09, 2001 at 08:25:43AM +0100, Daniela Engert wrote: > > > >They're about the same - only Alan didn't like the PCI speed measurement > > >code that's new in the 4.x series, so I added all the other changes to > > >the 3.20 driver, and 3.21 was born. > > > > I do understand Alan's objections against this speed measurement code > > very well. I have similar code built into other (non-Linux) drivers, > > and according to the many user reports that I got the measurement > > results should be taken with a grain of salt. It is working perfectly > > in most cases, but it may fail from time to time. There is a hidden > > assumption in this type of measurement which the device that you run > > the test against has to fulfill. If it doesn't (and it is not required > > to do to be conforming to the ATA spec), the measurement results (PCI > > bus clock) are bogus (typically way too high). > > Actually I don't think my method can ever result in a measurement higher > than real PCI clock, but can result in a lower one (if the device > deasserts IORDY even on a speed slower than PIO_0), which is also a > problem. Anyway, on fast machines the accuracy of the current algorithm > is +- .01 MHz. > > Once tested a little more, the measurement will probably go in, however > with an option for the user to override it with a command line > parameter. > > Btw, if it isn't a secret - what other drivers are those and what is the > exact method you used ... ? > > -- > Vojtech Pavlik > SuSE Labs > - > 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/ >
Andre Hedrick Linux ATA Development ASL Kernel Development ----------------------------------------------------------------------------- ASL, Inc. Toll free: 1-877-ASL-3535 1757 Houret Court Fax: 1-408-941-2071 Milpitas, CA 95035 Web: www.aslab.com
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