From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from SN4PR0501CU005.outbound.protection.outlook.com (mail-southcentralusazon11011039.outbound.protection.outlook.com [40.93.194.39]) (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 7944B30FF1D; Tue, 18 Aug 2026 05:32:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=fail smtp.client-ip=40.93.194.39 ARC-Seal:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787031145; cv=fail; b=Li6F2MLzq+x/AKntfUdqLkx7NEZaJMmm28lXivt9DXdil87ek6/bOw6Frd9oI+GjrwnQ3aqmZaCxlT5SfUCP0BMaPWc9mELW0z8lp7t2fQdgbDqPFuZOevk2pj+d9Vsh/xiKdfNZlmjVNdjuMK5LHvFqaiL4Vko6Ww3y//2mmgA= ARC-Message-Signature:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787031145; c=relaxed/simple; bh=rnI7v/JkFvMQq8TK9Ttry+2cs/6KfAaiS79sWbzFQU4=; h=Message-ID:Date:Subject:To:Cc:References:From:In-Reply-To: Content-Type:MIME-Version; b=tlMHXd7ImOb2Skt0BKWWyfUrOWFEenz4osD3rXTHIK5vWlgheVT5gf6zwa/oyNqGfMPThN0QaGhjly1voL4I+lwoyqqwOlouc6Levfd69LviRmOQ44+IvjkzLNu/0ZEDDR97CcQg7W+yhO22gUNXHtDdgSRyAvmFOqM9npsBKDA= ARC-Authentication-Results:i=2; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=nvidia.com; spf=fail smtp.mailfrom=nvidia.com; dkim=pass (2048-bit key) header.d=Nvidia.com header.i=@Nvidia.com header.b=J8ejSHLD; arc=fail smtp.client-ip=40.93.194.39 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=nvidia.com Authentication-Results: smtp.subspace.kernel.org; spf=fail smtp.mailfrom=nvidia.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=Nvidia.com header.i=@Nvidia.com header.b="J8ejSHLD" ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=aG8yQrInGZPRzX3/Q4dLWsxz/mj4Edirs4B2cyTE7wu2jtZzKPoZtVBdKgSASQHfjJIzKWTXnpaTzSenq+/lk1rEG+iw4SWu296eDf4x/da5/T7QYevW3FtsXMMaM5R10eXdoX+SvNIgl/F0O0V3Qeh2y5S4FIUP6ctG9XoFemunRRFKlXAs1Lku+5d2Iq7W5mbV31QTw06aTHCoba1oFdE5fhAwe0rqYgmZlQ200JG+1UuS3mVwqcui+ra/x72EQZQ1NEg2pPpGrwIGtOMwDEYWPhvw787RAJzSii48yYM0yelU01mMu0EZmMhj3cNBpmsmNhUMPdSR9LW9mgmRQw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector10001; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-AntiSpam-MessageData-ChunkCount:X-MS-Exchange-AntiSpam-MessageData-0:X-MS-Exchange-AntiSpam-MessageData-1; bh=RiUUxI/SyFBdRaTZiUcYuxtnyojmQgxyLZmQdQgjxto=; b=xYEpc25+2/YxZZ1W652TgD8mKBRmcIuILgDqXGmkmaWgvGDpFvUE4x6e40EHazcbRFMWVlPDtfFf4X/e6gU02orYxtoB8J09pgqftCBMbYo4CyPm7qr1hWTSWffTpOQG1VGPi6Q0mmpIHagr3Iv61Oi61lIG+uaDlaChDXZdqyBywREDEpZfht9YKJ4ewQXSJ0RcqhcALAHXFZG+f5Y9vqsj5rrL3C4a1pIPXSt3mUJa4QnKLwgAiTFjpo4zrO71vm8Nw8oPhR8mRvNMn5Z8jC3BdooaKBT0JgdAEkWr/k+odDquzNxB8xsVgxqTc61OaZXTFeOTu+hljTqyEZHzKQ== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=nvidia.com; dmarc=pass action=none header.from=nvidia.com; dkim=pass header.d=nvidia.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=Nvidia.com; s=selector2; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=RiUUxI/SyFBdRaTZiUcYuxtnyojmQgxyLZmQdQgjxto=; b=J8ejSHLDzu+WPwqDGcB9r9cASKxcwtnkZ1drkh5NFcKxKLXImaOC+GrPpljEyKlMxcA6LcAxHtwkRyf6iOkD/JSpUm9DwM6HCI/DIjJ7yoJnfVcE6awuUOyaEksfQ9HFIi4jNGR+L1HWPs5UpI7Otw5E3BHQL+eY2I65y+yic7O98JCk5blEHHKBRQajK7pQYesEUeLh3KmYABoQF9SB+jpXTm6f7xaDT6/TN3n6PPkOmSChFZu3GCyZrBDEC53urzOy4eFByOdxJ/mVMSVqAcK5m1fYabsOzqZCie+bfS0ARn8jBo15FL52+IF7gZG3mujc7OGDwbxPj+A0yQCGsw== Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=nvidia.com; Received: from SJ1PR12MB6051.namprd12.prod.outlook.com (2603:10b6:a03:48a::18) by BY5PR12MB4100.namprd12.prod.outlook.com (2603:10b6:a03:200::13) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.21.315.17; Tue, 18 Aug 2026 05:32:19 +0000 Received: from SJ1PR12MB6051.namprd12.prod.outlook.com ([fe80::96e1:b300:7b78:d3a9]) by SJ1PR12MB6051.namprd12.prod.outlook.com ([fe80::96e1:b300:7b78:d3a9%6]) with mapi id 15.21.0339.007; Tue, 18 Aug 2026 05:32:19 +0000 Message-ID: <3023d7d7-c8ab-48e7-a0e4-e18cc4ea0b9a@nvidia.com> Date: Tue, 18 Aug 2026 06:32:12 +0100 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH tty v9 1/2] serial: 8250: Switch to nbcon console, take 2 To: John Ogness , Greg Kroah-Hartman , Jiri Slaby Cc: Andy Shevchenko , Petr Mladek , Sebastian Andrzej Siewior , linux-kernel@vger.kernel.org, =?UTF-8?Q?Ilpo_J=C3=A4rvinen?= , Andy Shevchenko , Hugo Villeneuve , Fushuai Wang , Kees Cook , Stepan Ionichev , linux-serial@vger.kernel.org, "linux-tegra@vger.kernel.org" References: <20260724103654.133654-1-john.ogness@linutronix.de> <20260724103654.133654-2-john.ogness@linutronix.de> Content-Language: en-US From: Jon Hunter In-Reply-To: <20260724103654.133654-2-john.ogness@linutronix.de> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-ClientProxiedBy: FR3P281CA0125.DEUP281.PROD.OUTLOOK.COM (2603:10a6:d10:94::7) To SJ1PR12MB6051.namprd12.prod.outlook.com (2603:10b6:a03:48a::18) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: SJ1PR12MB6051:EE_|BY5PR12MB4100:EE_ X-MS-Office365-Filtering-Correlation-Id: 25b65575-00e1-4263-55cf-08defcea123f X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|23010399003|376014|7416014|366016|1800799024|10070799003|18002099003|22082099003|56012099006|4143699003|11063799006|10067099003; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:SJ1PR12MB6051.namprd12.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230040)(23010399003)(376014)(7416014)(366016)(1800799024)(10070799003)(18002099003)(22082099003)(56012099006)(4143699003)(11063799006)(10067099003);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 2 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?clpiQmg5bFVLS0owR0VRM3UvL1A3WUNlNUxUckJDRWw3SWlVd1JtQ1doU1Zr?= =?utf-8?B?TUVMd0lpdFlDeFpxby9nK3RnbVBpNXc1c2tJcGh0c2w1WkxCS0RhNHVCYWlx?= =?utf-8?B?Qys1dWhscGJqRGVvSkwwZ1hZOFp1cC9MNzlpR0tHU1JuZU45VGpOMmZpdmt3?= =?utf-8?B?R2tJODRMenh3S0gxendHU09qMnFXVzYyQ1VWZXpGakRUUzR6djJ5MFJwTzNR?= =?utf-8?B?QXozV09kMG41Q2RvTFlrTGNxVWJlWjZXWmhjM3NhQVFrUmNlRFFqdk9XQ0ly?= =?utf-8?B?dXo3aE13TUR6MEZmc2FxZkRuckordlI3dW0rYnlhN3pPc21GZHphSkJPb3pO?= =?utf-8?B?di92M2h0NFhUOVd1ODRoZVZiV0VEMm03OENrTzFiaW93QUIycW1nRGdZRndZ?= =?utf-8?B?Ukk5UnAwWmJhNHpIUGxKaVVxZzArYkFvcnM3bTRGbWxwa2ZCWHVYUEFubjhs?= =?utf-8?B?b3IvVWVOME4xZ1hqdk9yU3NaUDQ1K2t3d1F4ME45MjlMWjg2L2h1REFibllv?= =?utf-8?B?TmpOeDQycFRQZGdhZFY2eWFyYTRkVlU3M0NrOGN1NEttNkt2dW5lSDAzTStu?= =?utf-8?B?NVFzRWFHbG9vSUhLVno0clcwUkxsSnZwZG1MUW9sRzhkSFBLcFVlR3R3bWMy?= =?utf-8?B?bTNqQVdSeWtBZUZkc1pHWHRqZTBuZkYxUndHdG5MU3B6VkkrWGpMOTl1aGsx?= =?utf-8?B?dkltWkdJc3JDaFQzY2dqT1Z2S1Fpc1o2ZWFsbWhHM3NjVEl5Q0dhb09aSzFQ?= =?utf-8?B?R3VIbHVlVUw5YzY4NzFWcmlyRWFla2I0Q0JTbzBlWlRvQzhZb24yWUlpdkl6?= =?utf-8?B?aTBFWUoya080SkpjVG4vK3I0RmtJaE8yTzlsZ2RQS2dqblNsc0JBd0t4QlN6?= =?utf-8?B?c1RWdzk2cXpINC9ValI3b0NIZUFkLzF6TWRBUGQzUXhkME1IYjJKQ2dMUFZz?= =?utf-8?B?U3EyRnZMN0hYaTRLRDYzTnBHUFBsS3pmYnhCZ1hBQWhHVFU1OWVoTXJiN2lx?= =?utf-8?B?MU9nSXBDUnd6b1M5VmEyOVdXL1YvU2xRcEJkcGRwcGhDWlJXK280am5qQUFw?= =?utf-8?B?NENuM1p6L1lvQ1FYdC9iUm54amJoTGhadHRMRUJwZTEwdUIraW0zM2VkUUxh?= =?utf-8?B?ODdrbmF6QXBTQnpmS0xKZDdPaFRYaDZ4U1I0akV3NEl5MkcvbE4zZTlnTG8r?= =?utf-8?B?cmlXVHg1cFB3eHlRblBqVzNmUjB2Qnp0S216ZWpZZDJRSDk2M1pDeTZ1dlhh?= =?utf-8?B?M2ZQSUF5bTJzcjAzcGNWUXZuTUx2MVZuZ2E2eFhiM3dHdXF5MlpCWXYyWEVH?= =?utf-8?B?cktwc0w0ZXpEU1Z0aDE4bEVUMzVNNDEraDJWNXpNbjZaS3M0dEJwZW4vaDd3?= =?utf-8?B?T2NQNHBieG1XRlFSOFF2MTRZeG83a2dzR1BJTGVMMjdzRlQ2aXZXRXRoUFJa?= =?utf-8?B?ZlVMNmNLUjFtcWJiRFRNaDZBbmczTmgzc2x6bVNleUZxRzdVNldwcGh2Q3da?= =?utf-8?B?TVljdXhtYWg0QWVxQmt4bFNkSE9BYy9ZSTFuTEZXT2xhS1pIU01YZ2NUa0VO?= =?utf-8?B?QkRSUW9ybkE4dHRQbDF5WXZ5OEtsSEd4aEY5QmFGWEJMekZ1ZmRuYVBpZTJr?= =?utf-8?B?VlF1TlZyYy9iQ252QkVhbzBmaG54SHZ0SmsyQzViMGxneitNb1FoWDNidUFP?= =?utf-8?B?MGM2RTFlbm1EN0R0SGNoT0lWeG1QRW8weGNwZXJaQ2hoTGxyMmtHQlRtcW5z?= =?utf-8?B?YTZlcHY0THR6U2plczVSQ0Q0ekRQbUpOSit5ZzA4L0pPbEhwY1U5VEx2QkVv?= =?utf-8?B?K1hmblhiMmVVNDZtOEFsL0NZSWcvZWpPVC9rUUJoTzlGa2VCVi9GUXpsU2xr?= =?utf-8?B?OTZ5YlB2MFZscXNqbG50MGtaU2x2YTQ5RkVQS2pqdTBMVzExNWE2UkZlQ2Ez?= =?utf-8?B?clpTck5zSXdLck1qc2g5R3lwUTQrNFN4dDRMdlVsKzhwSGF0RHNUelBlYWlT?= =?utf-8?B?YU5aTzREV3FtWlpIVmdIU0dXNXVMSHdhK2t3WkR6c2RkSVcwaURWWWM3RWk0?= =?utf-8?B?WHFZMDgrdTluNHBzTGc4L2JUaXhEbjRxUVl1Nmw2a2Q4Yk9pVGZOTWoxWTN4?= =?utf-8?B?QzlISE16bkpZS0JOcUZ3MlQ3TGhwenB3RkZEZGxENDZSZzJQTThkekk5dW9h?= =?utf-8?B?MXE1d2FDRjBqdTFub1ZqN2RVbUVNSkc3WmdWUHQrOE5EL21FY3FDUXFBeThN?= =?utf-8?B?ejZuTEtFbTJwVUdaYmo1OVZBcytBdTczdjF1d29UZEVmdUhERCtGcHR5bVJM?= =?utf-8?B?VDJnbzgxelE1emZoRDArc0NCdXE2VHViemErSHpCUXdScHBzN3RNS3E1d2Ex?= =?utf-8?Q?dDKMVxyV96i+HrIOQCOSQiKNpl346Yfus3XjUZti9z9Zu?= X-MS-Exchange-AntiSpam-MessageData-1: 5NvLtxgh+4NuSA== X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 25b65575-00e1-4263-55cf-08defcea123f X-MS-Exchange-CrossTenant-AuthSource: SJ1PR12MB6051.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 18 Aug 2026 05:32:19.3286 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: CVnlTyOmjEfJHGOUR9nTILf/AiMxcagAxUwpCyiFWiPXuJUaWCgjGsQuwQqk/X/RIkMTNRe60dj0LtumUPY/oA== X-MS-Exchange-Transport-CrossTenantHeadersStamped: BY5PR12MB4100 Hi John, On 24/07/2026 11:36, John Ogness wrote: > Implement the necessary callbacks to switch the 8250 console driver > to perform as an nbcon console. > > Add implementations for the nbcon console callbacks: > > ->write_atomic() > ->write_thread() > ->device_lock() > ->device_unlock() > > and add CON_NBCON to the initial @flags. > > All hardware access in the callbacks is within unsafe sections. > The ->write_atomic() and ->write_thread() callbacks allow safe > handover/takeover per byte and add a preceding newline if they > take over from another context mid-line. > > For the ->write_atomic() callback, a new irq_work is used to defer > modem control since it may be called from a context that does not > allow waking up tasks. During suspend/resume the irq_work is not > used as this has been shown to cause suspend problems for some > hardware. Upon resume, any pending modem control is performed. > > Note: A new __serial8250_clear_IER() is introduced for direct > clearing of UART_IER during console writing (which will not be > holding the port lock for atomic printing or KDB/KGDB). This > allows restoring a lockdep check to serial8250_clear_IER() in > a follow-up commit. > > Signed-off-by: John Ogness This change is causing a boot regression for our Tegra20 and Tegra30 platforms. Reverting this on top of -next fixes the issue. Previously with V5 I did not see a boot issue only an issue in suspend. So far the only interesting thing I have observed is that if I add 'keep_bootcon' to the command line the board does boot. Jon -- nvpublic