Commit 3213b151 authored by Mathias Nyman's avatar Mathias Nyman Committed by Greg Kroah-Hartman

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

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 5cd43e33
"xhci 1.0: Set transfer burst count field."

Cc: stable@vger.kernel.org # 3.0
Suggested-by: default avatarShiChun Ma <masc2008@qq.com>
Signed-off-by: default avatarMathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 6fcfb0d6
......@@ -3537,7 +3537,7 @@ static unsigned int xhci_get_burst_count(struct xhci_hcd *xhci,
return 0;
max_burst = urb->ep->ss_ep_comp.bMaxBurst;
return roundup(total_packet_count, max_burst + 1) - 1;
return DIV_ROUND_UP(total_packet_count, max_burst + 1) - 1;
}
/*
......
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