From patchwork Sun Feb 4 03:19:57 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Yicong Yang X-Patchwork-Id: 196410 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:a05:7301:168b:b0:106:860b:bbdd with SMTP id ma11csp179796dyb; Sat, 3 Feb 2024 19:24:51 -0800 (PST) X-Google-Smtp-Source: AGHT+IHRiGp6EnWSdLNj7wJ/MAbXH0W3R/hv2ox8Rl1jy27MvRx2vXIeMUIteqxxpPfImbVAltPu X-Received: by 2002:a81:4e0e:0:b0:5ff:6ca0:4b19 with SMTP id c14-20020a814e0e000000b005ff6ca04b19mr12611685ywb.31.1707017090845; Sat, 03 Feb 2024 19:24:50 -0800 (PST) ARC-Seal: i=2; a=rsa-sha256; t=1707017090; cv=pass; d=google.com; s=arc-20160816; b=qAZmi5hAASj/eZroNMVQQqnHtV3kRQjcAAyTgad62O4/wEg5BS0Uk1ZosnwOnC+jaL phQn8UMNK8omiqxMuqTLkSXqjuod3awABKK+G33P93v1GSKOFLZreO94xQl0XLk2RWUh 2c2xw1InKz92VIgwFxD9eobs1Gb0en+6smROrjhrAzEMRLHHef6oNbduza9bjUwlk6tD iEwQW2kowKD7HWvcl4zXgpNd2+kLdGxQzwo5436bB3lRiq3lhLkMQurnJmyODvtSYloH pP1NHD6l0PB0kD2UC7ZAYMlarTbuLo8SGQ2wE1x3HgZm34CKV1MAX3V1fmFdPRIJuqSo /MUA== ARC-Message-Signature: i=2; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=content-transfer-encoding:mime-version:list-unsubscribe :list-subscribe:list-id:precedence:message-id:date:subject:cc:to :from; bh=j7htdFw0pX9Gd/mjwo6LTgqx1bjzjAclwi1idByh88E=; fh=NKoCj/4WcwZ2EFHEDOQOuXxCCcQXOFCjjFYbeweI3AI=; b=O0KgAKl6houi4tPFMAGNAM0S1N75j/nN+Rn0IIE8XFzPEEGhO1Rr8Pa3ADteV1eKJ+ mdeKWWWuLBL3CuLQTUqg/5KtGIVNhNqcXb+jA78b/zocEenlFuDYzNtsVhaIUdQX2ZqA uolkdy6N7DpH7XR6NyANsA2cQLDcvnwZMlFqgm007UVSRcPCIsam0tDyb/VeQBkCDqaH qdvsnMS5LvkWvj4zWubF1DzmkJXyM86JI8UnQ3WWcJsO7P/Ozlm6+OYLjly7y4/j/1QN DupX3ToTIcca+H7uy4Zdjag5yzft0mUXWGaC+lwQE6UYt2DIJDID4abV7MFKmRMn6ttd 9BIw==; dara=google.com ARC-Authentication-Results: i=2; mx.google.com; arc=pass (i=1 spf=pass spfdomain=huawei.com dmarc=pass fromdomain=huawei.com); spf=pass (google.com: domain of linux-kernel+bounces-51399-ouuuleilei=gmail.com@vger.kernel.org designates 2604:1380:45e3:2400::1 as permitted sender) smtp.mailfrom="linux-kernel+bounces-51399-ouuuleilei=gmail.com@vger.kernel.org"; dmarc=fail (p=QUARANTINE sp=QUARANTINE dis=NONE) header.from=huawei.com X-Forwarded-Encrypted: i=1; AJvYcCVW16EHuwfjMuKetbK68wa5gMql3IVQgYiVOS51mMiDwDiCwAceWBZUAY9wtu1xCIsPxvBqz8LLaFs1wHjsQMNjh3DbhQ== Received: from sv.mirrors.kernel.org (sv.mirrors.kernel.org. [2604:1380:45e3:2400::1]) by mx.google.com with ESMTPS id s3-20020a17090330c300b001d8f3a2e055si4058644plc.177.2024.02.03.19.24.50 for (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 03 Feb 2024 19:24:50 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel+bounces-51399-ouuuleilei=gmail.com@vger.kernel.org designates 2604:1380:45e3:2400::1 as permitted sender) client-ip=2604:1380:45e3:2400::1; Authentication-Results: mx.google.com; arc=pass (i=1 spf=pass spfdomain=huawei.com dmarc=pass fromdomain=huawei.com); spf=pass (google.com: domain of linux-kernel+bounces-51399-ouuuleilei=gmail.com@vger.kernel.org designates 2604:1380:45e3:2400::1 as permitted sender) smtp.mailfrom="linux-kernel+bounces-51399-ouuuleilei=gmail.com@vger.kernel.org"; dmarc=fail (p=QUARANTINE sp=QUARANTINE dis=NONE) header.from=huawei.com Received: from smtp.subspace.kernel.org (wormhole.subspace.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by sv.mirrors.kernel.org (Postfix) with ESMTPS id 74A4428482B for ; Sun, 4 Feb 2024 03:24:50 +0000 (UTC) Received: from localhost.localdomain (localhost.localdomain [127.0.0.1]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 1E30F610E; Sun, 4 Feb 2024 03:24:38 +0000 (UTC) Received: from szxga04-in.huawei.com (szxga04-in.huawei.com [45.249.212.190]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 686B87493; Sun, 4 Feb 2024 03:24:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.190 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707017076; cv=none; b=GJzvJUGq46i+Bp6fTG9NyppS4LBe7kXYksNTsj4HF/Sx8+K+GcQnw+0mpaAlWmBU0fqHQ4SEWgYKE6sp9FlnTPvL8ja5ecOTbpkVh97oPD1AUdRZWn0K2pqPrsXrh1RYj20xP/0aCPEE81JjJX3osURRRV9Ok22u3sEGpaphsrU= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707017076; c=relaxed/simple; bh=yDtEU9udkSi9sX7/bNnaQ8KwNv6DdunABj3WnokyXc0=; h=From:To:CC:Subject:Date:Message-ID:MIME-Version:Content-Type; b=DeAWfcW7xV4Nj3+sLUw5f/ES4/ngN+pJqVimgky1bLvshnwKfJ1Bf8THXTJ5pxOtrqyid0Y4p447mhHFBLzgdUv9SfILDaLCwKtCr0z+iQxGYBgYm8lp5zOMNjKbrcr0dujV1KV3DXzzYgBVzPkTYtcbS4c/SJ6hnvrHY+FKC0Q= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com; spf=pass smtp.mailfrom=huawei.com; arc=none smtp.client-ip=45.249.212.190 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huawei.com Received: from mail.maildlp.com (unknown [172.19.88.214]) by szxga04-in.huawei.com (SkyGuard) with ESMTP id 4TSFFs0mWZz1xnB5; Sun, 4 Feb 2024 11:23:13 +0800 (CST) Received: from canpemm500009.china.huawei.com (unknown [7.192.105.203]) by mail.maildlp.com (Postfix) with ESMTPS id 121CA1A016C; Sun, 4 Feb 2024 11:24:17 +0800 (CST) Received: from localhost.localdomain (10.50.165.33) by canpemm500009.china.huawei.com (7.192.105.203) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.35; Sun, 4 Feb 2024 11:24:16 +0800 From: Yicong Yang To: , , , , CC: , , , , , , , Subject: [PATCH] serial: port: Don't suspend if the port is still busy Date: Sun, 4 Feb 2024 11:19:57 +0800 Message-ID: <20240204031957.58176-1-yangyicong@huawei.com> X-Mailer: git-send-email 2.31.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-ClientProxiedBy: dggems706-chm.china.huawei.com (10.3.19.183) To canpemm500009.china.huawei.com (7.192.105.203) X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: 1789937153160469755 X-GMAIL-MSGID: 1789937153160469755 From: Yicong Yang We accidently met the issue that the bash prompt is not shown after the previous command done and until the next input if there's only one CPU (In our issue other CPUs are isolated by isolcpus=). Further analysis shows it's because the port entering runtime suspend even if there's still pending chars in the buffer and the pending chars will only be processed in next device resuming. We are using amba-pl011 and the problematic flow is like below: Bash                                         kworker tty_write()   file_tty_write()     n_tty_write()       uart_write()         __uart_start()           pm_runtime_get() // wakeup waker             queue_work()                                     pm_runtime_work()                                                rpm_resume()                                                 status = RPM_RESUMING                                                 serial_port_runtime_resume()                                                   port->ops->start_tx()                                                     pl011_tx_chars()                                                       uart_write_wakeup()         […]         __uart_start()           pm_runtime_get() < 0 // because runtime status = RPM_RESUMING                                // later data are not commit to the port driver                                                 status = RPM_ACTIVE                                                 rpm_idle() -> rpm_suspend() This patch tries to fix this by checking the port busy before entering runtime suspending. A runtime_suspend callback is added for the port driver. When entering runtime suspend the callback is invoked, if there's still pending chars in the buffer then request an runtime resume for handling this. Cc: Tony Lindgren Signed-off-by: Yicong Yang --- drivers/tty/serial/serial_port.c | 22 +++++++++++++++++++++- 1 file changed, 21 insertions(+), 1 deletion(-) diff --git a/drivers/tty/serial/serial_port.c b/drivers/tty/serial/serial_port.c index 88975a4df306..60d1eec6b6b7 100644 --- a/drivers/tty/serial/serial_port.c +++ b/drivers/tty/serial/serial_port.c @@ -46,8 +46,28 @@ static int serial_port_runtime_resume(struct device *dev) return 0; } +static int serial_port_runtime_suspend(struct device *dev) +{ + struct serial_port_device *port_dev = to_serial_base_port_device(dev); + struct uart_port *port; + unsigned long flags; + + port = port_dev->port; + + if (port->flags & UPF_DEAD) + return 0; + + spin_lock_irqsave(&port->lock, flags); + if (__serial_port_busy(port)) + pm_request_resume(dev); + spin_unlock_irqrestore(&port->lock, flags); + + return 0; +} + static DEFINE_RUNTIME_DEV_PM_OPS(serial_port_pm, - NULL, serial_port_runtime_resume, NULL); + serial_port_runtime_suspend, + serial_port_runtime_resume, NULL); static int serial_port_probe(struct device *dev) {