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>

4 files changed, 5 insertions, 11 deletions

diff --git a/drivers/usb/host/ehci-hcd.c b/drivers/usb/host/ehci-hcd.c
index 6bf6c42481e8..61eac96441de 100644
--- a/drivers/usb/host/ehci-hcd.c
+++ b/drivers/usb/host/ehci-hcd.c
@@ -503,7 +503,7 @@ static int ehci_init(struct usb_hcd *hcd)
 
         /* 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);
 
diff --git a/drivers/usb/host/ehci-pci.c b/drivers/usb/host/ehci-pci.c
index 2cb7d370c4ef..d1407f8d42b1 100644
--- a/drivers/usb/host/ehci-pci.c
+++ b/drivers/usb/host/ehci-pci.c
@@ -103,7 +103,6 @@ static int ehci_pci_setup(struct usb_hcd *hcd)
                 }
                 break;
         case PCI_VENDOR_ID_INTEL:
-                ehci->fs_i_thresh = 1;
                 if (pdev->device == PCI_DEVICE_ID_INTEL_CE4100_USB)
                         hcd->has_tt = 1;
                 break;
diff --git a/drivers/usb/host/ehci-sched.c b/drivers/usb/host/ehci-sched.c
index 7eb242f27c00..b764cab2ab9a 100644
--- a/drivers/usb/host/ehci-sched.c
+++ b/drivers/usb/host/ehci-sched.c
@@ -1391,15 +1391,11 @@ iso_stream_schedule (
          */
         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
diff --git a/drivers/usb/host/ehci.h b/drivers/usb/host/ehci.h
index 0564a63f5eb3..4ddf7c51616b 100644
--- a/drivers/usb/host/ehci.h
+++ b/drivers/usb/host/ehci.h
@@ -193,7 +193,6 @@ struct ehci_hcd {			/* one per controller */
         unsigned                has_amcc_usb23:1;
         unsigned                need_io_watchdog:1;
         unsigned                amd_pll_fix:1;
-        unsigned                fs_i_thresh:1;  /* Intel iso scheduling */
         unsigned                use_dummy_qh:1; /* AMD Frame List table quirk*/
         unsigned                has_synopsys_hc_bug:1; /* Synopsys HC */
         unsigned                frame_index_bug:1; /* MosChip (AKA NetMos) */