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

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commit 3213b15138 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 5cd43e33b9
"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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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Mathias Nyman 2014-06-24 17:14:41 +03:00 • committed by Greg Kroah-Hartman

parent 9dd9ec82c5

commit ac4c61cfa5

1 changed files with 1 additions and 1 deletions

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drivers/usb/host/xhci-ring.c

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