lkml.org 
[lkml]   [2014]   [Jul]   [24]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 3.11 061/128] xhci: correct burst count field for isoc transfers on 1.0 xhci hosts
Date
3.11.10.14 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Mathias Nyman <mathias.nyman@linux.intel.com>

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: Luis Henriques <luis.henriques@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 1cef7b36a187..bf2857b95c20 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;
}

/*
--
1.9.1


\
 
 \ /
  Last update: 2014-07-24 12:41    [W:0.517 / U:10.864 seconds]
©2003-2017 Jasper Spaans. hosted at Digital OceanAdvertise on this site