From sarah.a.sharp@linux.intel.com Mon Oct 12 15:13:10 2009 From: Sarah Sharp Date: Fri, 9 Oct 2009 12:28:41 -0700 Subject: USB: ehci: Fix IST boundary checking interval math. To: Greg KH Cc: linux-usb@vger.kernel.org, Alan Stern , David Brownell Message-ID: <20091009192841.GA5279@gamba.jf.intel.com> Content-Disposition: inline When the EHCI driver falls behind in its scheduling, the active stream's first empty microframe may be in the past with respect to the current microframe. The code attempts to move the starting microframe ("start") N number of microframes forward, where N is the interval of endpoint. However, stream->interval is a copy of the endpoint's bInterval, which is designated in frames for FS devices, and microframes for HS devices. Convert stream->interval to microframes before using it to move the starting microframe forward. Acked-by: Alan Stern Signed-off-by: Sarah Sharp Signed-off-by: Greg Kroah-Hartman --- drivers/usb/host/ehci-sched.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) --- a/drivers/usb/host/ehci-sched.c +++ b/drivers/usb/host/ehci-sched.c @@ -1400,6 +1400,10 @@ iso_stream_schedule ( goto fail; } + period = urb->interval; + if (!stream->highspeed) + period <<= 3; + now = ehci_readl(ehci, &ehci->regs->frame_index) % mod; /* when's the last uframe this urb could start? */ @@ -1417,8 +1421,8 @@ iso_stream_schedule ( /* Fell behind (by up to twice the slop amount)? */ if (start >= max - 2 * 8 * SCHEDULE_SLOP) - start += stream->interval * DIV_ROUND_UP( - max - start, stream->interval) - mod; + start += period * DIV_ROUND_UP( + max - start, period) - mod; /* Tried to schedule too far into the future? */ if (unlikely((start + sched->span) >= max)) { @@ -1441,10 +1445,6 @@ iso_stream_schedule ( /* NOTE: assumes URB_ISO_ASAP, to limit complexity/bugs */ - period = urb->interval; - if (!stream->highspeed) - period <<= 3; - /* find a uframe slot with enough bandwidth */ for (; start < (stream->next_uframe + period); start++) { int enough_space;