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>

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);
 

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;

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

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) */