Commit 3e619d04 authored by Alan Stern's avatar Alan Stern Committed by Greg Kroah-Hartman

USB: EHCI: fix bug in scheduling periodic split transfers

This patch (as1654) fixes a very old bug in ehci-hcd, connected with
scheduling of periodic split transfers.  The calculations for
full/low-speed bus usage are all carried out after the correction for
bit-stuffing has been applied, but the values in the max_tt_usecs
array assume it hasn't been.  The array should allow for allocation of
up to 90% of the bus capacity, which is 900 us, not 780 us.

The symptom caused by this bug is that any isochronous transfer to a
full-speed device with a maxpacket size larger than about 980 bytes is
always rejected with a -ENOSPC error.
Signed-off-by: default avatarAlan Stern <stern@rowland.harvard.edu>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent b09a61cc
...@@ -213,7 +213,7 @@ static inline unsigned char tt_start_uframe(struct ehci_hcd *ehci, __hc32 mask) ...@@ -213,7 +213,7 @@ static inline unsigned char tt_start_uframe(struct ehci_hcd *ehci, __hc32 mask)
} }
static const unsigned char static const unsigned char
max_tt_usecs[] = { 125, 125, 125, 125, 125, 125, 30, 0 }; max_tt_usecs[] = { 125, 125, 125, 125, 125, 125, 125, 25 };
/* carryover low/fullspeed bandwidth that crosses uframe boundries */ /* carryover low/fullspeed bandwidth that crosses uframe boundries */
static inline void carryover_tt_bandwidth(unsigned short tt_usecs[8]) static inline void carryover_tt_bandwidth(unsigned short tt_usecs[8])
......
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