On Fri, Nov 11, 2011 at 10:48:36AM +0800, Andiry Xu wrote: > On 11/11/2011 04:36 AM, Sarah Sharp wrote: > > I think there might be a couple other subtle issues, but I need to apply > > your patchset and check. > > > > Thanks, will submit again after your test. Ok, I think there's one more thing you need to think about. What happens if a driver is enqueueing an isochronous URB, and xhci_queue_isoc_tx_prepare() succeeds because there is enough room on the ring, but prepare_transfer() fails for the Nth TD because the endpoint ring state changed (see commit 522989a27)? That error handling code will mess with your TRB counting. inc_enq() will have been called for each isochronous TD that was queued, but when the Nth TD fails, the TDs will get turned into no-ops (with the cycle bit set to hardware-owned), and xhci_queue_isoc_tx() will simply reset the enqueue pointer to the TRB where the isochronous URB first started being enqueued. That means inc_enq() will be subtracting TRBs from the number of free TRBs that really need to get added back when the enqueue pointer gets moved back. You might want to search for other places where ep_ring->enqueue or ep_ring->dequeue gets set, to make sure the TRB counting behavior is correct. Sarah Sharp -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
