From patchwork Mon Jun 17 17:30:19 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kamal Mostafa X-Patchwork-Id: 251959 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from huckleberry.canonical.com (huckleberry.canonical.com [91.189.94.19]) by ozlabs.org (Postfix) with ESMTP id 683302C013D for ; Tue, 18 Jun 2013 03:33:34 +1000 (EST) Received: from localhost ([127.0.0.1] helo=huckleberry.canonical.com) by huckleberry.canonical.com with esmtp (Exim 4.76) (envelope-from ) id 1UodJ1-0002pC-L8; Mon, 17 Jun 2013 17:33:27 +0000 Received: from youngberry.canonical.com ([91.189.89.112]) by huckleberry.canonical.com with esmtp (Exim 4.76) (envelope-from ) id 1UodHJ-0001yW-9q for kernel-team@lists.ubuntu.com; Mon, 17 Jun 2013 17:31:41 +0000 Received: from c-67-160-231-42.hsd1.ca.comcast.net ([67.160.231.42] helo=fourier) by youngberry.canonical.com with esmtpsa (TLS1.0:DHE_RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1UodHI-0007Cb-AU; Mon, 17 Jun 2013 17:31:40 +0000 Received: from kamal by fourier with local (Exim 4.80) (envelope-from ) id 1UodHG-00064a-1P; Mon, 17 Jun 2013 10:31:38 -0700 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Subject: [PATCH 15/84] USB: revert periodic scheduling bugfix Date: Mon, 17 Jun 2013 10:30:19 -0700 Message-Id: <1371490288-23167-16-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 1.8.1.2 In-Reply-To: <1371490288-23167-1-git-send-email-kamal@canonical.com> References: <1371490288-23167-1-git-send-email-kamal@canonical.com> X-Extended-Stable: 3.8 Cc: Greg Kroah-Hartman , Kamal Mostafa , Alan Stern , Tim Richardson X-BeenThere: kernel-team@lists.ubuntu.com X-Mailman-Version: 2.1.14 Precedence: list List-Id: Kernel team discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: kernel-team-bounces@lists.ubuntu.com Sender: kernel-team-bounces@lists.ubuntu.com 3.8.13.3 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Alan Stern commit fdc03438f53a00294ed9939eb3a1f6db6f3d8963 upstream. This patch reverts commit 3e619d04159be54b3daa0b7036b0ce9e067f4b5d (USB: EHCI: fix bug in scheduling periodic split transfers). The commit was valid -- it fixed a real bug -- but the periodic scheduler in ehci-hcd is in such bad shape (especially the part that handles split transactions) that fixing one bug is very likely to cause another to surface. That's what happened in this case; the result was choppy and noisy playback on certain 24-bit audio devices. The only real fix will be to rewrite this entire section of code. My next project... This fixes https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1136110. Thanks to Tim Richardson for extra testing and feedback, and to Joseph Salisbury and Tyson Tan for tracking down the original source of the problem. Signed-off-by: Alan Stern CC: Joseph Salisbury CC: Tim Richardson Signed-off-by: Greg Kroah-Hartman Signed-off-by: Kamal Mostafa --- drivers/usb/host/ehci-sched.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/usb/host/ehci-sched.c b/drivers/usb/host/ehci-sched.c index 010f686..5a00ef3 100644 --- a/drivers/usb/host/ehci-sched.c +++ b/drivers/usb/host/ehci-sched.c @@ -213,7 +213,7 @@ static inline unsigned char tt_start_uframe(struct ehci_hcd *ehci, __hc32 mask) } static const unsigned char -max_tt_usecs[] = { 125, 125, 125, 125, 125, 125, 125, 25 }; +max_tt_usecs[] = { 125, 125, 125, 125, 125, 125, 30, 0 }; /* carryover low/fullspeed bandwidth that crosses uframe boundries */ static inline void carryover_tt_bandwidth(unsigned short tt_usecs[8])