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authorMathias Nyman <mathias.nyman@linux.intel.com>2014-06-24 17:14:41 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-07-09 11:13:59 -0700
commit5f84a7feacd84b28597663fba27fbdfa28c48bf5 (patch)
tree9754b3c12955c276265167344a32023c758c387e
parent58f550fa3177622189c477951c3aff8048fc2e11 (diff)
downloadlinux-linaro-stable-5f84a7feacd84b28597663fba27fbdfa28c48bf5.tar.gz
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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--drivers/usb/host/xhci-ring.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index bcfb08e41eb6..fe42cae6d1ef 100644
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -3590,7 +3590,7 @@ 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;
}
/*