From patchwork Tue Aug 30 16:03:13 2011 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ming Lei X-Patchwork-Id: 1113332 Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) by demeter1.kernel.org (8.14.4/8.14.4) with ESMTP id p7UG3gQS020962 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO) for ; Tue, 30 Aug 2011 16:04:08 GMT Received: from canuck.infradead.org ([2001:4978:20e::1]) by merlin.infradead.org with esmtps (Exim 4.76 #1 (Red Hat Linux)) id 1QyQmk-00064U-IK; Tue, 30 Aug 2011 16:03:34 +0000 Received: from localhost ([127.0.0.1] helo=canuck.infradead.org) by canuck.infradead.org with esmtp (Exim 4.76 #1 (Red Hat Linux)) id 1QyQmk-00068j-3Y; Tue, 30 Aug 2011 16:03:34 +0000 Received: from mail-qy0-f177.google.com ([209.85.216.177]) by canuck.infradead.org with esmtps (Exim 4.76 #1 (Red Hat Linux)) id 1QyQmg-000683-Dj for linux-arm-kernel@lists.infradead.org; Tue, 30 Aug 2011 16:03:31 +0000 Received: by qyk2 with SMTP id 2so4118840qyk.15 for ; Tue, 30 Aug 2011 09:03:27 -0700 (PDT) Received: by 10.142.239.3 with SMTP id m3mr3398475wfh.230.1314720207121; Tue, 30 Aug 2011 09:03:27 -0700 (PDT) Received: from localhost ([183.37.203.48]) by mx.google.com with ESMTPS id w18sm4139892wfg.21.2011.08.30.09.03.20 (version=TLSv1/SSLv3 cipher=OTHER); Tue, 30 Aug 2011 09:03:26 -0700 (PDT) From: ming.lei@canonical.com To: greg@kroah.com, stern@rowland.harvard.edu Subject: [PATCH] usb: ehci: make HC see up-to-date qh/qtd descriptor ASAP Date: Wed, 31 Aug 2011 00:03:13 +0800 Message-Id: <1314720193-26577-1-git-send-email-ming.lei@canonical.com> X-Mailer: git-send-email 1.7.4.1 X-CRM114-Version: 20090807-BlameThorstenAndJenny ( TRE 0.7.6 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20110830_120330_530426_F5B99CE3 X-CRM114-Status: GOOD ( 13.66 ) X-Spam-Score: -0.7 (/) X-Spam-Report: SpamAssassin version 3.3.1 on canuck.infradead.org summary: Content analysis details: (-0.7 points) pts rule name description ---- ---------------------- -------------------------------------------------- -0.7 RCVD_IN_DNSWL_LOW RBL: Sender listed at http://www.dnswl.org/, low trust [209.85.216.177 listed in list.dnswl.org] 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider (tom.leiming[at]gmail.com) 0.0 T_TO_NO_BRKTS_FREEMAIL To: misformatted and free email service Cc: linux-omap@vger.kernel.org, linux-usb@vger.kernel.org, Russell King , Ming Lei , linux-arm-kernel@lists.infradead.org X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: linux-arm-kernel-bounces@lists.infradead.org Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Greylist: IP, sender and recipient auto-whitelisted, not delayed by milter-greylist-4.2.6 (demeter1.kernel.org [140.211.167.41]); Tue, 30 Aug 2011 16:04:08 +0000 (UTC) From: Ming Lei This patch introduces the helper of ehci_sync_mem to flush qtd/qh into memory immediately on some ARM, so that HC can see the up-to-date qtd/qh descriptor asap. This patch fixs one performance bug on ARM Cortex A9 dual core platform, which has been reported on quite a few ARM machines (OMAP4, Tegra 2, snowball...), see details from link of https://bugs.launchpad.net/bugs/709245. The patch has been tested ok on OMAP4 panda A1 board, and the performance of 'dd' over usb mass storage can be increased from 4~5MB/sec to 14~16MB/sec after applying this patch. Cc: Alan Stern Cc: Russell King Signed-off-by: Ming Lei Signed-off-by: Alan Stern --- drivers/usb/host/ehci-q.c | 18 ++++++++++++++++++ drivers/usb/host/ehci.h | 17 +++++++++++++++++ 2 files changed, 35 insertions(+), 0 deletions(-) diff --git a/drivers/usb/host/ehci-q.c b/drivers/usb/host/ehci-q.c index 0917e3a..2719879 100644 --- a/drivers/usb/host/ehci-q.c +++ b/drivers/usb/host/ehci-q.c @@ -995,6 +995,12 @@ static void qh_link_async (struct ehci_hcd *ehci, struct ehci_qh *qh) head->qh_next.qh = qh; head->hw->hw_next = dma; + /* + * flush qh descriptor into memory immediately, + * see comments in qh_append_tds. + * */ + ehci_sync_mem(); + qh_get(qh); qh->xacterrs = 0; qh->qh_state = QH_STATE_LINKED; @@ -1082,6 +1088,18 @@ static struct ehci_qh *qh_append_tds ( wmb (); dummy->hw_token = token; + /* + * Writing to dma coherent buffer on ARM may + * be delayed to reach memory, so HC may not see + * hw_token of dummy qtd in time, which can cause + * the qtd transaction to be executed very late, + * and degrade performance a lot. ehci_sync_mem + * is added to flush 'token' immediatelly into + * memory, so that ehci can execute the transaction + * ASAP. + * */ + ehci_sync_mem(); + urb->hcpriv = qh_get (qh); } } diff --git a/drivers/usb/host/ehci.h b/drivers/usb/host/ehci.h index cc7d337..313d9d6 100644 --- a/drivers/usb/host/ehci.h +++ b/drivers/usb/host/ehci.h @@ -738,6 +738,23 @@ static inline u32 hc32_to_cpup (const struct ehci_hcd *ehci, const __hc32 *x) #endif +/* + * Writing to dma coherent memory on ARM may be delayed via L2 + * writing buffer, so introduce the helper which can flush L2 writing + * buffer into memory immediately, especially used to flush ehci + * descriptor to memory. + * */ +#ifdef CONFIG_ARM_DMA_MEM_BUFFERABLE +static inline void ehci_sync_mem() +{ + mb(); +} +#else +static inline void ehci_sync_mem() +{ +} +#endif + /*-------------------------------------------------------------------------*/ #ifndef DEBUG