diff options
Diffstat (limited to 'drivers/usb/host/xhci-hcd.c')
| -rw-r--r-- | drivers/usb/host/xhci-hcd.c | 64 |
1 files changed, 61 insertions, 3 deletions
diff --git a/drivers/usb/host/xhci-hcd.c b/drivers/usb/host/xhci-hcd.c index e5fbdcdbf67..36e440ce88e 100644 --- a/drivers/usb/host/xhci-hcd.c +++ b/drivers/usb/host/xhci-hcd.c @@ -613,12 +613,70 @@ exit: return ret; } -/* Remove from hardware lists - * completions normally happen asynchronously +/* + * Remove the URB's TD from the endpoint ring. This may cause the HC to stop + * USB transfers, potentially stopping in the middle of a TRB buffer. The HC + * should pick up where it left off in the TD, unless a Set Transfer Ring + * Dequeue Pointer is issued. + * + * The TRBs that make up the buffers for the canceled URB will be "removed" from + * the ring. Since the ring is a contiguous structure, they can't be physically + * removed. Instead, there are two options: + * + * 1) If the HC is in the middle of processing the URB to be canceled, we + * simply move the ring's dequeue pointer past those TRBs using the Set + * Transfer Ring Dequeue Pointer command. This will be the common case, + * when drivers timeout on the last submitted URB and attempt to cancel. + * + * 2) If the HC is in the middle of a different TD, we turn the TRBs into a + * series of 1-TRB transfer no-op TDs. (No-ops shouldn't be chained.) The + * HC will need to invalidate the any TRBs it has cached after the stop + * endpoint command, as noted in the xHCI 0.95 errata. + * + * 3) The TD may have completed by the time the Stop Endpoint Command + * completes, so software needs to handle that case too. + * + * This function should protect against the TD enqueueing code ringing the + * doorbell while this code is waiting for a Stop Endpoint command to complete. + * It also needs to account for multiple cancellations on happening at the same + * time for the same endpoint. + * + * Note that this function can be called in any context, or so says + * usb_hcd_unlink_urb() */ int xhci_urb_dequeue(struct usb_hcd *hcd, struct urb *urb, int status) { - return -ENOSYS; + unsigned long flags; + int ret; + struct xhci_hcd *xhci; + struct xhci_td *td; + unsigned int ep_index; + struct xhci_ring *ep_ring; + + xhci = hcd_to_xhci(hcd); + spin_lock_irqsave(&xhci->lock, flags); + /* Make sure the URB hasn't completed or been unlinked already */ + ret = usb_hcd_check_unlink_urb(hcd, urb, status); + if (ret || !urb->hcpriv) + goto done; + + xhci_dbg(xhci, "Cancel URB 0x%x\n", (unsigned int) urb); + ep_index = xhci_get_endpoint_index(&urb->ep->desc); + ep_ring = xhci->devs[urb->dev->slot_id]->ep_rings[ep_index]; + td = (struct xhci_td *) urb->hcpriv; + + ep_ring->cancels_pending++; + list_add_tail(&td->cancelled_td_list, &ep_ring->cancelled_td_list); + /* Queue a stop endpoint command, but only if this is + * the first cancellation to be handled. + */ + if (ep_ring->cancels_pending == 1) { + queue_stop_endpoint(xhci, urb->dev->slot_id, ep_index); + ring_cmd_db(xhci); + } +done: + spin_unlock_irqrestore(&xhci->lock, flags); + return ret; } /* Drop an endpoint from a new bandwidth configuration for this device. |