Commit cd3c18ba authored May 31, 2011 by Dmitry Torokhov Committed by Sarah Sharp Jun 05, 2011

USB: xhci - fix interval calculation for FS isoc endpoints



Full-speed isoc endpoints specify interval in exponent based form in
frames, not microframes, so we need to adjust accordingly.

NEC xHCI host controllers will return an error code of 0x11 if a full
speed isochronous endpoint is added with the Interval field set to
something less than 3 (2^3 = 8 microframes, or one frame).  It is
impossible for a full speed device to have an interval smaller than one
frame.

This was always an issue in the xHCI driver, but commit
dfa49c4a "USB: xhci - fix math in
xhci_get_endpoint_interval()" removed the clamping of the minimum value
in the Interval field, which revealed this bug.

This needs to be backported to stable kernels back to 2.6.31.

Reported-by: Matt Evans <matt@ozlabs.org>
Signed-off-by: Dmitry Torokhov <dtor@vmware.com>
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Cc: stable@kernel.org

parent f5182b41

drivers/usb/host/xhci-mem.c

+12 −2

Original line number	Diff line number	Diff line
		@@ -985,9 +985,19 @@ static unsigned int xhci_parse_exponent_interval(struct usb_device *udev,
		interval = clamp_val(ep->desc.bInterval, 1, 16) - 1;
		if (interval != ep->desc.bInterval - 1)
		dev_warn(&udev->dev,
		"ep %#x - rounding interval to %d microframes\n",
		"ep %#x - rounding interval to %d %sframes\n",
		ep->desc.bEndpointAddress,
		1 << interval);
		1 << interval,
		udev->speed == USB_SPEED_FULL ? "" : "micro");

		if (udev->speed == USB_SPEED_FULL) {
		/*
		* Full speed isoc endpoints specify interval in frames,
		* not microframes. We are using microframes everywhere,
		* so adjust accordingly.
		*/
		interval += 3; /* 1 frame = 2^3 uframes */
		}

		return interval;
		}

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