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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>
This commit is contained in:
Alan Stern 2012-09-28 16:01:34 -04:00 committed by Greg Kroah-Hartman
parent c3ee9b76aa
commit 98cae42d82
4 changed files with 5 additions and 11 deletions
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2
drivers/usb/host/ehci-hcd.c
View File

@ -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);

1
drivers/usb/host/ehci-pci.c
View File

@ -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;

12
drivers/usb/host/ehci-sched.c
View File

@ -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

1
drivers/usb/host/ehci.h
View File

@ -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) */