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authorAlan Stern <stern@rowland.harvard.edu>2013-05-14 13:57:19 -0400
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-05-15 13:42:45 -0400
commite1944017839d7dfbf7329fac4bdec8b4050edf5e (patch)
treeb08bcd9a27c99136da80968ed04820dac8a99dcb /drivers/usb/host
parent997ff893603c6455da4c5e26ba1d0f81adfecdfc (diff)
downloadop-kernel-dev-e1944017839d7dfbf7329fac4bdec8b4050edf5e.zip
op-kernel-dev-e1944017839d7dfbf7329fac4bdec8b4050edf5e.tar.gz
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.c2
-rw-r--r--drivers/usb/host/uhci-q.c2
2 files changed, 2 insertions, 2 deletions
diff --git a/drivers/usb/host/ohci-hcd.c b/drivers/usb/host/ohci-hcd.c
index 9e6de95..df1af0b 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 f0976d8..041c6dd 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)) {
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