From patchwork Mon Sep 15 14:00:09 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Frans Klaver X-Patchwork-Id: 4905941 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork1.web.kernel.org (Postfix) with ESMTP id 6AF989F2EC for ; Mon, 15 Sep 2014 14:04:49 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id E4B70202A1 for ; Mon, 15 Sep 2014 14:07:31 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.9]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 94D38200ED for ; Mon, 15 Sep 2014 14:07:30 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1XTWty-00086g-Ey; Mon, 15 Sep 2014 14:05:10 +0000 Received: from filter1.ibarracuda.nl ([83.247.7.10]) by bombadil.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1XTWsT-00048a-08 for linux-arm-kernel@lists.infradead.org; Mon, 15 Sep 2014 14:03:37 +0000 X-ASG-Debug-ID: 1410789671-0759e746c032420002-tbGyMd Received: from XSMCASSVR01.xsens-tech.local (rev-215.116.249.87.virtu.nl [87.249.116.215]) by filter1.ibarracuda.nl with ESMTP id W0xC63q4L6HGAYtD (version=TLSv1 cipher=AES128-SHA bits=128 verify=NO); Mon, 15 Sep 2014 16:01:12 +0200 (CEST) X-Barracuda-Envelope-From: Frans.Klaver@xsens.com X-Barracuda-AUTH-User: xsenscom X-Barracuda-Apparent-Source-IP: 87.249.116.215 Received: from ci00147.xsens-tech.local (172.16.11.160) by XSMCASSVR01.xsens-tech.local (192.168.0.248) with Microsoft SMTP Server id 14.3.195.1; Mon, 15 Sep 2014 16:01:12 +0200 From: Frans Klaver To: Tony Lindgren Subject: [PATCH 3/4] tty: omap-serial: use threaded interrupt handler Date: Mon, 15 Sep 2014 16:00:09 +0200 X-ASG-Orig-Subj: [PATCH 3/4] tty: omap-serial: use threaded interrupt handler Message-ID: <1410789610-23059-4-git-send-email-frans.klaver@xsens.com> X-Mailer: git-send-email 2.1.0 In-Reply-To: <1410789610-23059-1-git-send-email-frans.klaver@xsens.com> References: <1410789610-23059-1-git-send-email-frans.klaver@xsens.com> MIME-Version: 1.0 X-Originating-IP: [172.16.11.160] X-Barracuda-Connect: rev-215.116.249.87.virtu.nl[87.249.116.215] X-Barracuda-Start-Time: 1410789672 X-Barracuda-Encrypted: AES128-SHA X-Barracuda-URL: http://filter1.ibarracuda.nl:8000/cgi-mod/mark.cgi X-Virus-Scanned: by bsmtpd at ibarracuda.nl X-Barracuda-BRTS-Status: 1 X-Barracuda-Spam-Score: 0.00 X-Barracuda-Spam-Status: No, SCORE=0.00 using per-user scores of TAG_LEVEL=1000.0 QUARANTINE_LEVEL=1000.0 KILL_LEVEL=5.0 tests= X-Barracuda-Spam-Report: Code version 3.2, rules version 3.2.3.9505 Rule breakdown below pts rule name description ---- ---------------------- -------------------------------------------------- X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20140915_070337_436299_6002A6C7 X-CRM114-Status: GOOD ( 12.50 ) X-Spam-Score: 0.0 (/) Cc: Mark Rutland , Frans Klaver , Alexey Pelykh , Pawel Moll , Ian Campbell , Greg Kroah-Hartman , linux-kernel@vger.kernel.org, Felipe Balbi , devicetree@vger.kernel.org, Rob Herring , linux-serial@vger.kernel.org, Kumar Gala , linux-omap@vger.kernel.org, Jiri Slaby , linux-arm-kernel@lists.infradead.org X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Spam-Status: No, score=-2.6 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_NONE, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP At 3.6Mbaud, with slightly over 2Mbit/s data coming in, we see 1600 uart rx buffer overflows within 30 seconds. Threading the interrupt handling reduces this to about 170 overflows in 10 minutes. In practice this therefore reduces the need for hardware flow control, meaning the sending side doesn't have to buffer as much either. Signed-off-by: Frans Klaver --- drivers/tty/serial/omap-serial.c | 30 +++++++++++++++++++++++------- 1 file changed, 23 insertions(+), 7 deletions(-) diff --git a/drivers/tty/serial/omap-serial.c b/drivers/tty/serial/omap-serial.c index 7d3f557..398139a 100644 --- a/drivers/tty/serial/omap-serial.c +++ b/drivers/tty/serial/omap-serial.c @@ -575,6 +575,20 @@ static void serial_omap_rdi(struct uart_omap_port *up, unsigned int lsr) } /** + * serial_omap_fast_irq() - schedule interrupt handling + */ +static irqreturn_t serial_omap_fast_irq(int irq, void *dev_id) +{ + struct uart_omap_port *up = dev_id; + unsigned int iir = serial_in(up, UART_IIR); + + if (iir & UART_IIR_NO_INT) + return IRQ_NONE; + + return IRQ_WAKE_THREAD; +} + +/** * serial_omap_irq() - This handles the interrupt from one port * @irq: uart port irq number * @dev_id: uart port info @@ -584,7 +598,6 @@ static irqreturn_t serial_omap_irq(int irq, void *dev_id) struct uart_omap_port *up = dev_id; unsigned int iir, lsr; unsigned int type; - irqreturn_t ret = IRQ_NONE; int max_count = 256; spin_lock(&up->port.lock); @@ -595,7 +608,6 @@ static irqreturn_t serial_omap_irq(int irq, void *dev_id) if (iir & UART_IIR_NO_INT) break; - ret = IRQ_HANDLED; lsr = serial_in(up, UART_LSR); /* extract IRQ type from IIR register */ @@ -634,7 +646,7 @@ static irqreturn_t serial_omap_irq(int irq, void *dev_id) pm_runtime_put_autosuspend(up->dev); up->port_activity = jiffies; - return ret; + return IRQ_HANDLED; } static unsigned int serial_omap_tx_empty(struct uart_port *port) @@ -731,15 +743,19 @@ static int serial_omap_startup(struct uart_port *port) /* * Allocate the IRQ */ - retval = request_irq(up->port.irq, serial_omap_irq, up->port.irqflags, - up->name, up); + retval = request_threaded_irq(up->port.irq, serial_omap_fast_irq, + serial_omap_irq, + IRQF_ONESHOT | up->port.irqflags, + up->name, up); if (retval) return retval; /* Optional wake-up IRQ */ if (up->wakeirq) { - retval = request_irq(up->wakeirq, serial_omap_irq, - up->port.irqflags, up->name, up); + retval = request_threaded_irq(up->wakeirq, serial_omap_fast_irq, + serial_omap_irq, + IRQF_ONESHOT | up->port.irqflags, + up->name, up); if (retval) { free_irq(up->port.irq, up); return retval;