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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D2A5CC433EF for ; Wed, 1 Jun 2022 11:25:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1351199AbiFALZJ (ORCPT ); Wed, 1 Jun 2022 07:25:09 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46914 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1352643AbiFALZB (ORCPT ); Wed, 1 Jun 2022 07:25:01 -0400 Received: from alexa-out-sd-02.qualcomm.com (alexa-out-sd-02.qualcomm.com [199.106.114.39]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CA3FC4664A; Wed, 1 Jun 2022 04:24:55 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=quicinc.com; i=@quicinc.com; q=dns/txt; s=qcdkim; t=1654082695; x=1685618695; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=oU0TXYjoeSYGvAnbOhKPOk9x41DF16IWFxcwFwX4/jk=; b=BXXzCvkAVE+x1nrWk9cm8K/wneNJ905rcBpZiGet47nVQpErtLsJXMu1 m6JD+3MgqSF/0jIGf3vUswoXXLtsBxCUzjeQkxOBnim2CS3ZTzq7Sof1u 5HYl5NjclljtE+lR7Yx6Kz/IhUae5aTGJalB6Zmw4+B6Sl0lx3Se9eBbv 8=; Received: from unknown (HELO ironmsg03-sd.qualcomm.com) ([10.53.140.143]) by alexa-out-sd-02.qualcomm.com with ESMTP; 01 Jun 2022 04:24:55 -0700 X-QCInternal: smtphost Received: from nasanex01c.na.qualcomm.com ([10.47.97.222]) by ironmsg03-sd.qualcomm.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 01 Jun 2022 04:24:55 -0700 Received: from nalasex01a.na.qualcomm.com (10.47.209.196) by nasanex01c.na.qualcomm.com (10.47.97.222) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.986.22; Wed, 1 Jun 2022 04:24:54 -0700 Received: from [10.216.8.63] (10.80.80.8) by nalasex01a.na.qualcomm.com (10.47.209.196) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.986.22; Wed, 1 Jun 2022 04:24:51 -0700 Message-ID: Date: Wed, 1 Jun 2022 16:54:48 +0530 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.9.1 Subject: Re: [V4] serial: core: Do stop_rx in suspend path for console if console_suspend is disabled Content-Language: en-CA To: Marek Szyprowski , , , , CC: , , , References: <1652692810-31148-1-git-send-email-quic_vnivarth@quicinc.com> <3866c083-0064-ac9a-4587-91a83946525d@samsung.com> From: Vijaya Krishna Nivarthi In-Reply-To: <3866c083-0064-ac9a-4587-91a83946525d@samsung.com> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.80.80.8] X-ClientProxiedBy: nasanex01a.na.qualcomm.com (10.52.223.231) To nalasex01a.na.qualcomm.com (10.47.209.196) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On 5/24/2022 5:24 PM, Marek Szyprowski wrote: > On 23.05.2022 23:32, Marek Szyprowski wrote: >> Hi, >> >> On 16.05.2022 11:20, Vijaya Krishna Nivarthi wrote: >>> For the case of console_suspend disabled, if back to back suspend/resume >>> test is executed, at the end of test, sometimes console would appear to >>> be frozen not responding to input. This would happen because, during >>> resume, rx transactions can come in before system is ready, malfunction >>> of rx happens in turn resulting in console appearing to be stuck. >>> >>> Do a stop_rx in suspend sequence to prevent this. >>> >>> Signed-off-by: Vijaya Krishna Nivarthi >>> --- >>> v4: moved the change to serial core to apply for all drivers >>> v3: swapped the order of conditions to be more human readable >>> v2: restricted patch to contain only stop_rx in suspend sequence >>> v1: intial patch contained 2 additional unrelated changes in vicinity >>> --- >> This patch landed recently in linux-next as commit c9d2325cdb92 >> ("serial: core: Do stop_rx in suspend path for console if >> console_suspend is disabled"). >> >> Unfortunately it breaks console operation on my test systems after >> system suspend/resume cycle if 'no_console_suspend' kernel parameter >> is present. System properly resumes from suspend, the console displays >> all the messages and even command line prompt, but then doesn't react >> on any input. If I remove the 'no_console_suspend' parameter, the >> console is again operational after system suspend/resume cycle. Before >> this patch it worked fine regardless the 'no_console_suspend' parameter. >> >> If this matters, the test system is ARM 32bit Samsung Exynos5422-based >> Odroid XU3lite board. > > One more information. This issue can be easily reproduced with QEMU. It > happens both on ARM 32bit and ARM 64bit QEMU's 'virt' machines when > 'no_console_suspend' is added to kernel's cmdline. > Ideally, as comments indicate, the set_termios should have done stop_rx at begin and start_rx at end to take care of this issue. This is probably missing in your driver. Can we check if this can be fixed? OR other option is Add a start_rx in uart_resume_port after call to set_termios to handle this scenario for other drivers. Please let me know if there are any concerns for this options. >>>   drivers/tty/serial/serial_core.c | 11 +++++++++-- >>>   1 file changed, 9 insertions(+), 2 deletions(-) >>> >>> diff --git a/drivers/tty/serial/serial_core.c >>> b/drivers/tty/serial/serial_core.c >>> index 82a1770..9a85b41 100644 >>> --- a/drivers/tty/serial/serial_core.c >>> +++ b/drivers/tty/serial/serial_core.c >>> @@ -2211,9 +2211,16 @@ int uart_suspend_port(struct uart_driver *drv, >>> struct uart_port *uport) >>>       } >>>       put_device(tty_dev); >>>   -    /* Nothing to do if the console is not suspending */ >>> -    if (!console_suspend_enabled && uart_console(uport)) >>> +    /* >>> +     * Nothing to do if the console is not suspending >>> +     * except stop_rx to prevent any asynchronous data >>> +     * over RX line. Re-start_rx, when required, is >>> +     * done by set_termios in resume sequence >>> +     */ >>> +    if (!console_suspend_enabled && uart_console(uport)) { >>> +        uport->ops->stop_rx(uport); >>>           goto unlock; >>> +    } >>>         uport->suspended = 1; >> Best regards > Best regards Thank you.