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-hcd.c b/drivers/usb/host/ehci-hcd.c
index 6bf6c42..61eac96 100644
--- a/drivers/usb/host/ehci-hcd.c
+++ b/drivers/usb/host/ehci-hcd.c
@@ -503,7 +503,7 @@
/* controllers may cache some of the periodic schedule ... */
if (HCC_ISOC_CACHE(hcc_params)) // full frame cache
- ehci->i_thresh = 2 + 8;
+ ehci->i_thresh = 0;
else // N microframes cached
ehci->i_thresh = 2 + HCC_ISOC_THRES(hcc_params);