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    SubjectRE: USB mass storage and ARM cache coherency
    On Tue, 16 Feb 2010, Shilimkar, Santosh wrote:

    > > Your original patch however kills ehci, ohci and uhci on some architectures.
    > Well the patch was making _ONLY_ control transfers use PIO and rest of
    > the transfer would still use dma. So not sure how much performance impact would
    > be because of that.
    > Another issue with that patch is there are few controllers which can't do PIO
    > at all and hence the patch would broke those controllers.

    More than "a few"! None of the EHCI, OHCI, or UHCI controllers used in
    Intel-compatible desktop and laptop systems can do PIO. That's what
    Oliver meant.

    Alan Stern

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      Last update: 2010-02-16 16:47    [W:0.028 / U:3.760 seconds]
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