linux-kernel - Re: [PATCH v2 1/1] usb: xhci: apply XHCI_AVOID

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Date:	Thu, 12 Mar 2015 15:36:00 -0400
From:	Devin Heitmueller <dheitmueller@...nellabs.com>
To:	Lu Baolu <baolu.lu@...ux.intel.com>
Cc:	Mathias Nyman <mathias.nyman@...el.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	linux-usb@...r.kernel.org,
	Linux Kernel <linux-kernel@...r.kernel.org>,
	stable@...r.kernel.org
Subject: Re: [PATCH v2 1/1] usb: xhci: apply XHCI_AVOID_BEI quirk to all Intel
 xHCI controllers

On Thu, Mar 12, 2015 at 6:15 AM, Lu Baolu <baolu.lu@...ux.intel.com> 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 Intel xHCI host controllers, if the event ring is full
> of events from transfers with BEI set,  an "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 the 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.
>
> This patch is to apply XHCI_AVOID_BEI quirk to Intel xHC 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 <baolu.lu@...ux.intel.com>
> Cc: stable@...r.kernel.org
> ---
>  drivers/usb/host/xhci-pci.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/usb/host/xhci-pci.c b/drivers/usb/host/xhci-pci.c
> index fd53c9e..2af32e2 100644
> --- a/drivers/usb/host/xhci-pci.c
> +++ b/drivers/usb/host/xhci-pci.c
> @@ -115,6 +115,7 @@ static void xhci_pci_quirks(struct device *dev, struct xhci_hcd *xhci)
>         if (pdev->vendor == PCI_VENDOR_ID_INTEL) {
>                 xhci->quirks |= XHCI_LPM_SUPPORT;
>                 xhci->quirks |= XHCI_INTEL_HOST;
> +               xhci->quirks |= XHCI_AVOID_BEI;
>         }
>         if (pdev->vendor == PCI_VENDOR_ID_INTEL &&
>                         pdev->device == PCI_DEVICE_ID_INTEL_PANTHERPOINT_XHCI) {
> @@ -130,7 +131,6 @@ static void xhci_pci_quirks(struct device *dev, struct xhci_hcd *xhci)
>                  * PPT chipsets.
>                  */
>                 xhci->quirks |= XHCI_SPURIOUS_REBOOT;
> -               xhci->quirks |= XHCI_AVOID_BEI;
>         }
>         if (pdev->vendor == PCI_VENDOR_ID_INTEL &&
>                 pdev->device == PCI_DEVICE_ID_INTEL_LYNXPOINT_LP_XHCI) {
> --
> 2.1.0
>

Looks good for me to (tested with an HVR-950q on a 2013 Macbook Pro (Haswell).

Tested by: Devin Heitmueller <dheitmueller@...nellabs.com>

Thanks for your help,

Devin

-- 
Devin J. Heitmueller - Kernel Labs
http://www.kernellabs.com
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