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    Revert "xhci 1.0: Limit arbitrarily-aligned scatter gather." · e2ed5114
    Mathias Nyman 提交于
    This reverts commit 247bf557.
    
    This commit, together with commit 3804fad4
    "USBNET: ax88179_178a: enable tso if usb host supports sg dma" were
    origially added to get xHCI 1.0 hosts and usb ethernet ax88179_178a devices
    working together with scatter gather. xHCI 1.0 hosts pose some requirement on how transfer
    buffers are aligned, setting this requirement for 1.0 hosts caused USB 3.0 mass
    storage devices to fail more frequently.
    
    USB 3.0 mass storage devices used to work before 3.14-rc1.  Theoretically,
    the TD fragment rules could have caused an occasional disk glitch.
    Now the devices *will* fail, instead of theoretically failing.
    >From a user perspective, this looks like a regression; the USB device obviously
    fails on 3.14-rc1, and may sometimes silently fail on prior kernels.
    
    The proper soluition is to implement the TD fragment rules required, but for now
    this patch needs to be reverted to get USB 3.0 mass storage devices working at the
    level they used to.
    Signed-off-by: NMathias Nyman <mathias.nyman@linux.intel.com>
    Cc: stable <stable@vger.kernel.org>
    Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    e2ed5114
xhci.c 145.1 KB