UPSTREAM: USB: EHCI: fix bug in scheduling periodic split transfers

UPSTREAM: 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>
(cherry picked from commit 5b70af1c0b0088151a1e7a8917527e190ddd76d7)

BUG=None
TEST=Together with other cherry-picks: run BVT trybots on all platforms,
manually confirm that USB network/storage/input devices still work
(including across suspend/resume)

Change-Id: I610be3b44ef6c3006050491029520834121964be
Signed-off-by: Julius Werner <jwerner@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/46074
Reviewed-by: Vincent Palatin <vpalatin@chromium.org>