3.9-stable review patch. If anyone has any objections, please let me know.
------------------ From: Alan Stern <[email protected]> commit e1944017839d7dfbf7329fac4bdec8b4050edf5e upstream. Commits c44b225077bb1fb25ed5cd5c4f226897b91bedd4 (UHCI: implement new semantics for URB_ISO_ASAP) and 6a41b4d3fe8cd4cc95181516fc6fba7b1747a27c (OHCI: implement new semantics for URB_ISO_ASAP) increased the latency for isochronous URBs in uhci-hcd and ohci-hcd respectively to 2 milliseconds, in an attempt to avoid underruns. It turns out that not only was this unnecessary -- 1-ms latency works okay -- it also causes problems with certain application loads such as real-time audio. This patch changes the latency for both drivers back to 1 ms. This should be applied to -stable kernels going back to 3.8. Signed-off-by: Alan Stern <[email protected]> Reported-and-tested-by: Joe Rayhawk <[email protected]> CC: Clemens Ladisch <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- drivers/usb/host/ohci-hcd.c | 2 +- drivers/usb/host/uhci-q.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) --- a/drivers/usb/host/ohci-hcd.c +++ b/drivers/usb/host/ohci-hcd.c @@ -233,7 +233,7 @@ static int ohci_urb_enqueue ( urb->start_frame = frame; } } else if (ed->type == PIPE_ISOCHRONOUS) { - u16 next = ohci_frame_no(ohci) + 2; + u16 next = ohci_frame_no(ohci) + 1; u16 frame = ed->last_iso + ed->interval; /* Behind the scheduling threshold? */ --- a/drivers/usb/host/uhci-q.c +++ b/drivers/usb/host/uhci-q.c @@ -1287,7 +1287,7 @@ static int uhci_submit_isochronous(struc return -EINVAL; /* Can't change the period */ } else { - next = uhci->frame_number + 2; + next = uhci->frame_number + 1; /* Find the next unused frame */ if (list_empty(&qh->queue)) { -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
