[3.13.y.z extended stable] Patch "xhci: correct burst count field for isoc transfers on 1.0 xhci hosts" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

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

to the linux-3.13.y-queue branch of the 3.13.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.13.y-queue

This patch is scheduled to be released in version 3.13.11.6.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.13.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From 4c0ce08415cd2d3ff2d45773cd41602ea31f836f Mon Sep 17 00:00:00 2001
From: Mathias Nyman <mathias.nyman at linux.intel.com>
Date: Tue, 24 Jun 2014 17:14:41 +0300
Subject: 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 at qq.com>
Signed-off-by: Mathias Nyman <mathias.nyman at linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 drivers/usb/host/xhci-ring.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index da3a91b..d0d906f 100644
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -3680,7 +3680,7 @@ 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;
 }

 /*
--
1.9.1