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    SubjectRe: [RFC] Align tegra-ehci DMA transfers to 32B
    On Fri, Dec 17, 2010 at 02:32:27PM -0800, Greg KH wrote:
    > On Fri, Dec 17, 2010 at 01:58:47PM -0800, Robert Morell wrote:
    > > This small set of patches fixes an issue where DMA from the tegra EHCI
    > > controller could be corrupted. It was most commonly seen with USB network
    > > adapters, though in theory it could happen with any USB traffic.
    > >
    > > (Note: An attempt was made to fix this with commit 367c3aab, which set
    > > NET_IP_ALIGN to 0 and NET_SKB_PAD to 32. Unfortunately, not all network
    > > drivers honor them (presumably since these are intended as optimizations rather
    > > than hard rules). This does mean that properly-written network drivers should
    > > fall through this code with very little overhead, however.)
    > We don't have many USB network drivers, why not just fix them up to
    > handle this properly, then you will not need to change any core USB
    > code, right?

    The USB core code is used by devices other than USB adapters. We've
    only seen this problem so far with usbnet devices, but I can't test
    every USB device ever to make sure that they always align their DMA to
    32 bytes.


    > thanks,
    > greg k-h

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      Last update: 2010-12-17 23:49    [W:0.037 / U:38.256 seconds]
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