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    SubjectRe: [34-longterm 094/247] OHCI: work around for nVidia shutdown problem
    On Thu, 23 Jun 2011, Paul Gortmaker wrote:

    > From: Alan Stern <>
    > -------------------
    > This is a commit scheduled for the next v2.6.34 longterm release.
    > If you see a problem with using this for longterm, please comment.
    > -------------------
    > commit 3df7169e73fc1d71a39cffeacc969f6840cdf52b upstream.
    > This patch (as1417) fixes a problem affecting some (or all) nVidia
    > chipsets. When the computer is shut down, the OHCI controllers
    > continue to power the USB buses and evidently they drive a Reset
    > signal out all their ports. This prevents attached devices from going
    > to low power. Mouse LEDs stay on, for example, which is disconcerting
    > for users and a drain on laptop batteries.
    > The fix involves leaving each OHCI controller in the OPERATIONAL state
    > during system shutdown rather than putting it in the RESET state.
    > Although this nominally means the controller is running, in fact it's
    > not doing very much since all the schedules are all disabled. However
    > there is ongoing DMA to the Host Controller Communications Area, so
    > the patch also disables the bus-master capability of all PCI USB
    > controllers after the shutdown routine runs.
    > The fix is applied only to nVidia-based PCI OHCI controllers, so it
    > shouldn't cause problems on systems using other hardware. As an added
    > safety measure, in case the kernel encounters one of these running
    > controllers during boot, the patch changes quirk_usb_handoff_ohci()
    > (which runs early on during PCI discovery) to reset the controller
    > before anything bad can happen.

    This commit caused problems on systems using later NVIDIA hardware. It
    shouldn't be merged unless the upstream commit


    is merged also.

    Alan Stern

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