From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753449AbaHDQ7F (ORCPT ); Mon, 4 Aug 2014 12:59:05 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:56585 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752041AbaHDQt4 (ORCPT ); Mon, 4 Aug 2014 12:49:56 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "ShiChun Ma" , "Mathias Nyman" , "Greg Kroah-Hartman" Date: Mon, 04 Aug 2014 17:48:31 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 09/94] xhci: correct burst count field for isoc transfers on 1.0 xhci hosts In-Reply-To: X-SA-Exim-Connect-IP: 192.168.4.249 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.2.62-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Mathias Nyman 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 Signed-off-by: Mathias Nyman Signed-off-by: Greg Kroah-Hartman Signed-off-by: Ben Hutchings --- drivers/usb/host/xhci-ring.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/drivers/usb/host/xhci-ring.c +++ b/drivers/usb/host/xhci-ring.c @@ -3521,7 +3521,7 @@ static unsigned int xhci_get_burst_count 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; } /*