From nobody Tue Dec 16 13:55:40 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E16ABCDB47E for ; Fri, 13 Oct 2023 11:48:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231354AbjJMLsv convert rfc822-to-8bit (ORCPT ); Fri, 13 Oct 2023 07:48:51 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58240 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230458AbjJMLsu (ORCPT ); Fri, 13 Oct 2023 07:48:50 -0400 Received: from postfix2.imaqliq.com (postfix2.imaqliq.com [93.189.151.48]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 12E06A9; Fri, 13 Oct 2023 04:48:48 -0700 (PDT) Received: from verse.imaqliq.com (unknown [93.189.151.95]) by postfix2.imaqliq.com (Postfix) with ESMTP id 18A371C2B9C; Fri, 13 Oct 2023 14:48:46 +0300 (MSK) MIME-Version: 1.0 Sensitivity: Importance: Normal X-Priority: 3 (Normal) In-Reply-To: References: Subject: [PATCH v4] tty: serial: meson: fix hard LOCKUP on crtscts mode From: Pavel Krasavin To: Greg Kroah-Hartman , Jiri Slaby , Neil Armstrong , Kevin Hilman , Jerome Brunet , Martin Blumenstingl Cc: linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-amlogic@lists.infradead.org Date: Fri, 13 Oct 2023 11:48:39 +0000 Message-ID: X-Mailer: Lotus Domino Web Server Release 12.0.2 November 03, 2022 X-MIMETrack: Serialize by http on verse/com(Release 12.0.2|November 03, 2022) at 10/13/2023 11:48:39, Serialize complete at 10/13/2023 11:48:39, Serialize by Router on verse/com(Release 12.0.2|November 03, 2022) at 10/13/2023 11:48:45 X-KeepSent: 55521400:7512350F-00258A47:003F7254; type=4; name=$KeepSent Content-Transfer-Encoding: quoted-printable X-KLMS-Rule-ID: 1 X-KLMS-Message-Action: clean X-KLMS-AntiSpam-Lua-Profiles: 180603 [Oct 13 2023] X-KLMS-AntiSpam-Version: 6.0.0.2 X-KLMS-AntiSpam-Envelope-From: pkrasavin@imaqliq.com X-KLMS-AntiSpam-Rate: 10 X-KLMS-AntiSpam-Status: not_detected X-KLMS-AntiSpam-Method: none X-KLMS-AntiSpam-Auth: dmarc=fail header.from=imaqliq.com policy=none;spf=softfail smtp.mailfrom=imaqliq.com;dkim=none X-KLMS-AntiSpam-Info: LuaCore: 539 539 807534d9021bfe9ca369c363d15ac993cd93d4d9, {rep_avail}, {Tracking_uf_ne_domains}, {Tracking_from_domain_doesnt_match_to}, 93.189.151.95:7.1.2;d41d8cd98f00b204e9800998ecf8427e.com:7.1.1;127.0.0.199:7.1.2;verse.imaqliq.com:7.1.1;imaqliq.com:7.1.1;lore.kernel.org:7.1.1;gdc.ru:7.1.1, FromAlignment: s, {Tracking_dmark_f}, ApMailHostAddress: 93.189.151.95 X-MS-Exchange-Organization-SCL: -1 X-KLMS-AntiSpam-Interceptor-Info: scan successful X-KLMS-AntiPhishing: Clean, bases: 2023/10/13 11:23:00 X-KLMS-AntiVirus: Kaspersky Security for Linux Mail Server, version 8.0.3.30, bases: 2023/10/13 08:46:00 #22180318 X-KLMS-AntiVirus-Status: Clean, skipped Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Pavel Krasavin There might be hard lockup if we set crtscts mode on port without RTS/CTS c= onfigured: # stty -F /dev/ttyAML6 crtscts; echo 1 > /dev/ttyAML6; echo 2 > /dev/ttyAML6 [ 95.890386] rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: [ 95.890857] rcu: 3-...0: (201 ticks this GP) idle=3De33c/1/0x4000000= 000000000 softirq=3D5844/5846 fqs=3D4984 [ 95.900212] rcu: (detected by 2, t=3D21016 jiffies, g=3D7753, q=3D29= 6 ncpus=3D4) [ 95.906972] Task dump for CPU 3: [ 95.910178] task:bash state:R running task stack:0 p= id:205 ppid:1 flags:0x00000202 [ 95.920059] Call trace: [ 95.922485] __switch_to+0xe4/0x168 [ 95.925951] 0xffffff8003477508 [ 95.974379] watchdog: Watchdog detected hard LOCKUP on cpu 3 [ 95.974424] Modules linked in: 88x2cs(O) rtc_meson_vrtc Possible solution would be to not allow to setup crtscts on such port. Tested on S905X3 based board. Signed-off-by: Pavel Krasavin --- v4: More correct patch subject according to Jiri's note v3: https://lore.kernel.org/lkml/OF6CF5FFA0.CCFD0E8E-ON00258A46.00549EDF-00= 258A46.0054BB62@gdc.ru/ "From:" line added to the mail v2: https://lore.kernel.org/lkml/OF950BEF72.7F425944-ON00258A46.00488A76-00= 258A46.00497D44@gdc.ru/ braces for single statement removed according to Dmitry's note v1: https://lore.kernel.org/lkml/OF28B2B8C9.5BC0CD28-ON00258A46.0037688F-00= 258A46.0039155B@gdc.ru/ --- --- a/drivers/tty/serial/meson_uart.c 2023-10-12 15:44:02.410538523 +0300 +++ b/drivers/tty/serial/meson_uart.c 2023-10-12 15:58:06.242395253 +0300 @@ -380,10 +380,14 @@ static void meson_uart_set_termios(struc else val |=3D AML_UART_STOP_BIT_1SB; =20 - if (cflags & CRTSCTS) - val &=3D ~AML_UART_TWO_WIRE_EN; - else + if (cflags & CRTSCTS) { + if (port->flags & UPF_HARD_FLOW) + val &=3D ~AML_UART_TWO_WIRE_EN; + else + termios->c_cflag &=3D ~CRTSCTS; + } else { val |=3D AML_UART_TWO_WIRE_EN; + } =20 writel(val, port->membase + AML_UART_CONTROL); =20 @@ -705,6 +709,7 @@ static int meson_uart_probe(struct platf u32 fifosize =3D 64; /* Default is 64, 128 for EE UART_0 */ int ret =3D 0; int irq; + bool has_rtscts; =20 if (pdev->dev.of_node) pdev->id =3D of_alias_get_id(pdev->dev.of_node, "serial"); @@ -732,6 +737,7 @@ static int meson_uart_probe(struct platf return irq; =20 of_property_read_u32(pdev->dev.of_node, "fifo-size", &fifosize); + has_rtscts =3D of_property_read_bool(pdev->dev.of_node, "uart-has-rtscts"= ); =20 if (meson_ports[pdev->id]) { return dev_err_probe(&pdev->dev, -EBUSY, @@ -762,6 +768,8 @@ static int meson_uart_probe(struct platf port->mapsize =3D resource_size(res_mem); port->irq =3D irq; port->flags =3D UPF_BOOT_AUTOCONF | UPF_LOW_LATENCY; + if (has_rtscts) + port->flags |=3D UPF_HARD_FLOW; port->has_sysrq =3D IS_ENABLED(CONFIG_SERIAL_MESON_CONSOLE); port->dev =3D &pdev->dev; port->line =3D pdev->id;