From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-19.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 65D8FC433FE for ; Thu, 16 Sep 2021 16:27:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4F29461A80 for ; Thu, 16 Sep 2021 16:27:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242056AbhIPQ2z (ORCPT ); Thu, 16 Sep 2021 12:28:55 -0400 Received: from mail.kernel.org ([198.145.29.99]:53832 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241275AbhIPQPZ (ORCPT ); Thu, 16 Sep 2021 12:15:25 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id E211B6127B; Thu, 16 Sep 2021 16:11:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1631808691; bh=/0JtWiTJOi4JRW8g7IDSKPFVPSInRC6zR4wkgle/4Ro=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=fi3pVomqbQLMGgKMGCvOi4mT9YmQgCPCPOCh+ji0KUlR3UJWdYAqdUroI7oUEPxkD L9f+GqG4XS7HCa4Xr/6HQRWZX1VceLYEVCRO5LmjKaT56qS66eYC5FQZ/WmhKci7nA xgsO4FUAfsWNQ41x1axMRSkdRQlYTRUIM2OfC6Z0= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Carl Philipp Klemm , Merlijn Wajer , Pavel Machek , Sebastian Reichel , Vignesh Raghavendra , Tony Lindgren , Sasha Levin Subject: [PATCH 5.10 187/306] serial: 8250_omap: Handle optional overrun-throttle-ms property Date: Thu, 16 Sep 2021 17:58:52 +0200 Message-Id: <20210916155800.457449753@linuxfoundation.org> X-Mailer: git-send-email 2.33.0 In-Reply-To: <20210916155753.903069397@linuxfoundation.org> References: <20210916155753.903069397@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Tony Lindgren [ Upstream commit 1fe0e1fa3209ad8e9124147775bd27b1d9f04bd4 ] Handle optional overrun-throttle-ms property as done for 8250_fsl in commit 6d7f677a2afa ("serial: 8250: Rate limit serial port rx interrupts during input overruns"). This can be used to rate limit the UART interrupts on noisy lines that end up producing messages like the following: ttyS ttyS2: 4 input overrun(s) At least on droid4, the multiplexed USB and UART port is left to UART mode by the bootloader for a debug console, and if a USB charger is connected on boot, we get noise on the UART until the PMIC related drivers for PHY and charger are loaded. With this patch and overrun-throttle-ms = <500> we avoid the extra rx interrupts. Cc: Carl Philipp Klemm Cc: Merlijn Wajer Cc: Pavel Machek Cc: Sebastian Reichel Cc: Vignesh Raghavendra Signed-off-by: Tony Lindgren Link: https://lore.kernel.org/r/20210727103533.51547-2-tony@atomide.com Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin --- drivers/tty/serial/8250/8250_omap.c | 25 ++++++++++++++++++++++++- 1 file changed, 24 insertions(+), 1 deletion(-) diff --git a/drivers/tty/serial/8250/8250_omap.c b/drivers/tty/serial/8250/8250_omap.c index c37468887fd2..efe4cf32add2 100644 --- a/drivers/tty/serial/8250/8250_omap.c +++ b/drivers/tty/serial/8250/8250_omap.c @@ -617,7 +617,7 @@ static irqreturn_t omap8250_irq(int irq, void *dev_id) struct uart_port *port = dev_id; struct omap8250_priv *priv = port->private_data; struct uart_8250_port *up = up_to_u8250p(port); - unsigned int iir; + unsigned int iir, lsr; int ret; #ifdef CONFIG_SERIAL_8250_DMA @@ -628,6 +628,7 @@ static irqreturn_t omap8250_irq(int irq, void *dev_id) #endif serial8250_rpm_get(up); + lsr = serial_port_in(port, UART_LSR); iir = serial_port_in(port, UART_IIR); ret = serial8250_handle_irq(port, iir); @@ -642,6 +643,24 @@ static irqreturn_t omap8250_irq(int irq, void *dev_id) serial_port_in(port, UART_RX); } + /* Stop processing interrupts on input overrun */ + if ((lsr & UART_LSR_OE) && up->overrun_backoff_time_ms > 0) { + unsigned long delay; + + up->ier = port->serial_in(port, UART_IER); + if (up->ier & (UART_IER_RLSI | UART_IER_RDI)) { + port->ops->stop_rx(port); + } else { + /* Keep restarting the timer until + * the input overrun subsides. + */ + cancel_delayed_work(&up->overrun_backoff); + } + + delay = msecs_to_jiffies(up->overrun_backoff_time_ms); + schedule_delayed_work(&up->overrun_backoff, delay); + } + serial8250_rpm_put(up); return IRQ_RETVAL(ret); @@ -1353,6 +1372,10 @@ static int omap8250_probe(struct platform_device *pdev) } } + if (of_property_read_u32(np, "overrun-throttle-ms", + &up.overrun_backoff_time_ms) != 0) + up.overrun_backoff_time_ms = 0; + priv->wakeirq = irq_of_parse_and_map(np, 1); pdata = of_device_get_match_data(&pdev->dev); -- 2.30.2