tree b08bcd9a27c99136da80968ed04820dac8a99dcb
parent 997ff893603c6455da4c5e26ba1d0f81adfecdfc
author Alan Stern <stern@rowland.harvard.edu> 1368554239 -0400
committer Greg Kroah-Hartman <gregkh@linuxfoundation.org> 1368639765 -0400

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>