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Alan Stern authored
Commit 24f53137 (USB: EHCI: accept very late isochronous URBs) changed the isochronous API provided by ehci-hcd. URBs submitted too late, so that the time slots for all their packets have already expired, are no longer rejected outright. Instead the submission is accepted, and the URB completes normally with a -EXDEV error for each packet. This is what client drivers expect. This patch implements the same policy in ohci-hcd. The change is more complicated than it was in ehci-hcd, because ohci-hcd doesn't scan for isochronous completions in the same way as ehci-hcd does. Rather, it depends on the hardware adding completed TDs to a "done queue". Some OHCI controller don't handle this properly when a TD's time slot has already expired, so we have to avoid adding such TDs to the schedule in the first place. As a result, if the URB was submitted too late then none of its TDs will get put on the schedule, so none of them will end up on the done queue, so the driver will never realize that the URB should be completed. To solve this problem, the patch adds one to urb_priv->td_cnt for such URBs, making it larger than urb_priv->length (td_cnt already gets set to the number of TD's that had to be skipped because their slots have expired). Each time an URB is given back, the finish_urb() routine looks to see if urb_priv->td_cnt for the next URB on the same endpoint is marked in this way. If so, it gives back the next URB right away. This should be applied to all kernels containing commit 815fa7b9 (USB: OHCI: fix logic for scheduling isochronous URBs). Signed-off-by: Alan Stern <stern@rowland.harvard.edu> CC: <stable@vger.kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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