On Fri, 19 Jul 2013, Gioh Kim wrote: > > I was going to ask the same question. This particular piece of code gets > > executed _only_ when an URB is unlinked. Not during any other kind of > > error. > > > I've got the problem when I listened to the mp3 file of USB HDD. > I checked the urb data when the problem occurred, the last-status value of > urb was EINPROGRESS and > urb->unlinked was ECONNRESET. Ah, so the URB _was_ unlinked. > I think the 'stopped' case was occurred by the reset of USB port. > The block device driver did reset USB port because there is no return from > USB device. Okay. > If I made block device driver could not reset USB port, the EHCI driver > codes were not executed. > Finally the halt of HC makes 'stopped' case. Why was the HC halted? That should happen only when there is an extremely severe error. > I think halt of the HC might be caused that store-buffer delays command for > HC. > When I applied the patch from https://lkml.org/lkml/2011/8/31/344 and added > a mb() into hw_next updating > to remove delay of store-buffer, My platform works well. > > Can the store-buffer delay halt HC? Is it possible? I don't see how. It could slow things down but it should not cause any errors. > IMHO, if the qTD list is broken the HC think there is no qTD to send. > So I added mb() at hw_next update code. At the time when the hw_next update gets executed, what is the value of "state"? It should be QH_STATE_IDLE. Alan Stern -- 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
