tree 5a08276818746722b3da78d0e0bcceacededecac
parent 52b2c470fc1c00cc0b6f2c9d7ff079df6cce346c
author Mathias Nyman <mathias.nyman@linux.intel.com> 1403619281 +0300
committer Matthias Kaehlcke <mka@google.com> 1433366108 -0700

xhci: correct burst count field for isoc transfers on 1.0 xhci hosts

commit 3213b151387df0b95f4eada104f68eb1c1409cb3 upstream.

The transfer burst count (TBC) field in xhci 1.0 hosts should be set
to the number of bursts needed to transfer all packets in a isoc TD.
Supported values are 0-2 (1 to 3 bursts per service interval).

Formula for TBC calculation is given in xhci spec section 4.11.2.3:
TBC = roundup( Transfer Descriptor Packet Count / Max Burst Size +1 ) - 1

This patch should be applied to stable kernels since 3.0 that contain
the commit 5cd43e33b9519143f06f507dd7cbee6b7a621885
"xhci 1.0: Set transfer burst count field."

Suggested-by: ShiChun Ma <masc2008@qq.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>