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    SubjectRe: [PATCH 039/173] OHCI: work around for nVidia shutdown problem
    On Mon, 25 Apr 2011, Willy Tarreau wrote:

    > 2.6.27.59-stable review patch. If anyone has any objections, please let us know.
    >
    > ------------------
    >
    > From: Alan Stern <stern@rowland.harvard.edu>
    >
    > 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.
    >
    > Reported-by: Pali Rohár <pali.rohar@gmail.com>
    > Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
    > CC: David Brownell <david-b@pacbell.net>
    > Tested-by: Pali Rohár <pali.rohar@gmail.com>
    > Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

    Some people have reported that more recent Nvidia systems work
    correctly without this patch and have problems when the patch is
    applied. For now, I suggest omitting this patch.

    Alan Stern

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