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

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Date:	Thu, 12 Mar 2015 16:48:42 +0800
From:	"Lu, Baolu" <baolu.lu@...ux.intel.com>
To:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
CC:	Mathias Nyman <mathias.nyman@...el.com>,
	dheitmueller@...nellabs.com, linux-usb@...r.kernel.org,
	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH 1/1] usb: xhci: apply XHCI_AVOID_BEI quirk to Intel ValleyView
 and LynxPoint LP



On 03/12/2015 03:54 PM, Greg Kroah-Hartman wrote:
> 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 <baolu.lu@...ux.intel.com>
>> Cc: stable@...r.kernel.org
>> ---
>>   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 @@
>>   #define PCI_DEVICE_ID_INTEL_CHERRYVIEW_XHCI		0x22b5
>>   #define PCI_DEVICE_ID_INTEL_SUNRISEPOINT_H_XHCI		0xa12f
>>   #define PCI_DEVICE_ID_INTEL_SUNRISEPOINT_LP_XHCI	0x9d2f
>> +#define	PCI_DEVICE_ID_INTEL_VALLEYVIEW_XHCI		0x0f35
> Minor nit, you added a tab where the rest of the file was using a space
> :(

Yes, thanks for reminding.

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