Commit c06d4dcf authored Jan 24, 2008 by David Brownell Committed by Greg Kroah-Hartman Feb 01, 2008

usb: ehci should use u16 for isochronous intervals



While most isochronous endpoints have short polling intervals, the
EHCI driver won't necessarily handle larger ones correctly.

This patch switches to use a "u16" to represent those periods, not
a u8, since it can always work:  the largest expressible period
is 2^15 units ... not the previous too-short limit of 128 frames
(full or low speeds) or microframes (high speed, 32 frames).

This bug is essentially theoretical, since the few ISO endpoints
I've seen which don't use one transfer per frame are high speed
ones using more than that (including high bandwidth, 24 KB/msec).

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

parent cd4cdc93

drivers/usb/host/ehci.h

+1 −1

Original line number	Diff line number	Diff line
		@@ -550,8 +550,8 @@ struct ehci_iso_stream {
		* trusting urb->interval == f(epdesc->bInterval) and
		* including the extra info for hw_bufp[0..2]
		*/
		u8 interval;
		u8 usecs, c_usecs;
		u16 interval;
		u16 tt_usecs;
		u16 maxp;
		u16 raw_mask;

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