On 03/12/2015 04:46 PM, Mathias Nyman wrote:
On 12.03.2015 03:39, 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.")Maybe we should set the quirk for all Intel xHCI controllers. So far the list includes Pantherpoint, Lynxpoint and valleyview. I bet it concerns most Intel platforms.
Yes, I agree with you. I will send out a new patch for this.
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