Re: [PATCH 1/1] usb: xhci: apply XHCI_AVOID_BEI quirk to Intel ValleyView and LynxPoint LP

From: Greg Kroah-Hartman
Date: Thu Mar 12 2015 - 03:54:42 EST

On Thu, Mar 12, 2015 at 09:39:06AM +0800, Lu Baolu wrote:
> When a device with an isochronous endpoint is plugged into the Intel
> xHCI host controller, and the driver submits multiple frames per URB,
> the xHCI driver will set the Block Event Interrupt (BEI) flag on all
> but the last TD for the URB. This causes the host controller to place
> an event on the event ring, but not send an interrupt. When the last
> TD for the URB completes, BEI is cleared, and we get an interrupt for
> the whole URB.
> However, under some Intel xHCI host controllers like ValleyView and
> Lynx Point LP, if the event ring is full of events from transfers with
> BEI set, a "Event Ring is Full" event will be posted to the last entry
> of the event ring, but no interrupt is generated. Host will cease all
> transfer and command executions and wait until software completes
> handling the pending events in event ring. That means xHC stops but
> event of "event ring is full" is not notified. As the result, the xHC
> looks like dead to user.
> The patch is to apply XHCI_AVOID_BEI to Intel VallyView and Lynx Point
> LP devices. And it should be backported to kernels as old as 3.0, that
> contains the commit 69e848c2090a ("Intel xhci: Support EHCI/xHCI port
> switching.")
> Signed-off-by: Lu Baolu <>
> Cc: stable@xxxxxxxxxxxxxxx
> ---
> drivers/usb/host/xhci-pci.c | 5 +++++
> 1 file changed, 5 insertions(+)
> diff --git a/drivers/usb/host/xhci-pci.c b/drivers/usb/host/xhci-pci.c
> index fd53c9e..5aa4893 100644
> --- a/drivers/usb/host/xhci-pci.c
> +++ b/drivers/usb/host/xhci-pci.c
> @@ -40,6 +40,7 @@

Minor nit, you added a tab where the rest of the file was using a space
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