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| author | Alan Stern <stern@rowland.harvard.edu> | 2013-05-14 13:57:19 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-05-15 13:42:45 -0400 |
| commit | e1944017839d7dfbf7329fac4bdec8b4050edf5e (patch) | |
| tree | b08bcd9a27c99136da80968ed04820dac8a99dcb /drivers/usb/host | |
| parent | 997ff893603c6455da4c5e26ba1d0f81adfecdfc (diff) | |
| download | blackbird-op-linux-e1944017839d7dfbf7329fac4bdec8b4050edf5e.tar.gz blackbird-op-linux-e1944017839d7dfbf7329fac4bdec8b4050edf5e.zip | |
USB: fix latency in uhci-hcd and ohci-hcd
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 <stern@rowland.harvard.edu>
Reported-and-tested-by: Joe Rayhawk <jrayhawk@fairlystable.org>
CC: Clemens Ladisch <clemens@ladisch.de>
CC: <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/usb/host')
| -rw-r--r-- | drivers/usb/host/ohci-hcd.c | 2 | ||||
| -rw-r--r-- | drivers/usb/host/uhci-q.c | 2 |
2 files changed, 2 insertions, 2 deletions
diff --git a/drivers/usb/host/ohci-hcd.c b/drivers/usb/host/ohci-hcd.c index 9e6de9586ae4..df1af0bcfe99 100644 --- 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? */ diff --git a/drivers/usb/host/uhci-q.c b/drivers/usb/host/uhci-q.c index f0976d8190bc..041c6ddb695c 100644 --- a/drivers/usb/host/uhci-q.c +++ b/drivers/usb/host/uhci-q.c @@ -1287,7 +1287,7 @@ static int uhci_submit_isochronous(struct uhci_hcd *uhci, struct urb *urb, 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)) { |
