diff options
| author | Alan Stern <stern@rowland.harvard.edu> | 2013-01-30 16:36:40 -0500 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-02-11 08:16:48 -0800 |
| commit | f3f2759e76bfbd10f1612cf7f3d9d6e16fee1782 (patch) | |
| tree | b92681728e08d27c13f9836ac8002b274b41a4f1 | |
| parent | 9e268451a7fed8c0defbe08eb32e11228eecde58 (diff) | |
| download | lwn-f3f2759e76bfbd10f1612cf7f3d9d6e16fee1782.tar.gz lwn-f3f2759e76bfbd10f1612cf7f3d9d6e16fee1782.zip | |
USB: EHCI: fix bug in scheduling periodic split transfers
commit 3e619d04159be54b3daa0b7036b0ce9e067f4b5d upstream.
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: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/usb/host/ehci-sched.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/usb/host/ehci-sched.c b/drivers/usb/host/ehci-sched.c index 8949b239decc..53192f2e2c75 100644 --- a/drivers/usb/host/ehci-sched.c +++ b/drivers/usb/host/ehci-sched.c @@ -236,7 +236,7 @@ static inline unsigned char tt_start_uframe(struct ehci_hcd *ehci, __hc32 mask) } 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 */ static inline void carryover_tt_bandwidth(unsigned short tt_usecs[8]) |