EHCI: use the isochronous scheduling threshold
This patch (as1609) changes the way ehci-hcd uses the "Isochronous
Scheduling Threshold" in its calculations. Until now the code has
ignored the threshold except for certain Intel PCI-based controllers.
This violates the EHCI spec.
The new code takes the threshold into account always, removing the
need for the fs_i_thresh quirk flag. In addition it implements the
"full frame cache" setting more efficiently, moving forward only as
far as the next frame boundary instead of always moving forward 8
microframes.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/usb/host/ehci-sched.c b/drivers/usb/host/ehci-sched.c
index 7eb242f..b764cab 100644
--- a/drivers/usb/host/ehci-sched.c
+++ b/drivers/usb/host/ehci-sched.c
@@ -1391,15 +1391,11 @@
*/
if (likely (!list_empty (&stream->td_list))) {
- /* For high speed devices, allow scheduling within the
- * isochronous scheduling threshold. For full speed devices
- * and Intel PCI-based controllers, don't (work around for
- * Intel ICH9 bug).
- */
- if (!stream->highspeed && ehci->fs_i_thresh)
- next = now + ehci->i_thresh;
+ /* Take the isochronous scheduling threshold into account */
+ if (ehci->i_thresh)
+ next = now + ehci->i_thresh; /* uframe cache */
else
- next = now;
+ next = (now + 2 + 7) & ~0x07; /* full frame cache */
/*
* Use ehci->last_iso_frame as the base. There can't be any