From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.19]) (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 967B5347BD7; Tue, 18 Aug 2026 06:14:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.175.65.19 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787033698; cv=none; b=fwAtoRU37wYGXz3kvd7iNkFMGtD7TPG5DJTrltZaRCD85F1IZTBKZGMGKhI9QA3lGHODRHv/b5O01C2RFAbzMEXrJFaYEhrd0048Bku0Xl/A+ia47Y/AnTT+GdkneUnEec2aetpQEz5Cwyb4Ql2LGrf1wmdnuSBN0I29qqrr6b8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787033698; c=relaxed/simple; bh=qmM93o9jv0NTkaOlDD7aB7TzWSk+F2gZPiTnShlYhI8=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=UmIobewR56rKmyTUkPMTXjLOZGAcSGcb6cZGMFC6Sdnniyaqv2dp0ElUtV2KU4aRt7/8Att5yuJ5jKiDmz/zBrlX7u+zQJ3sqrLkU1A1gqa+EG7/xGztNw7gT7K4InOEtWwuEJ6AXYdhiqRzW6proC9tjvwwjMFI1247NNsApT0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com; spf=pass smtp.mailfrom=linux.intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=b9HIKrPy; arc=none smtp.client-ip=198.175.65.19 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="b9HIKrPy" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1787033697; x=1818569697; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=qmM93o9jv0NTkaOlDD7aB7TzWSk+F2gZPiTnShlYhI8=; b=b9HIKrPyXA7TgZ3Q1DpbLGjPGwXpGmiy6mspsKlv2Zudv2rcNp27KDcw /yt0SZkmuyu1zYOy03r2HLZmENjAF2cJGh7AeAIfLmjjeLhJnv5UeZWbx VxJoJLPetj6ozoZbLkB+5vdx3+KWrLZEasu2GHkEo5+r+0KOyTdsZfO0l IeyEPG8K0XEdQZ4ZEJaHFwbRAu0mgMwRsQyC9q28XcCOd+ypmyat1xVNA AaprAjcw/ZIRoq8UtzS94OiwA6Yn3PBUXKEvdkv2MeLwmKS9pyJclLgg2 KuSfvCcKe373G5LtU1K0lhDgPXQT+u0a67pRBRBcYfKZlvdGG2cIMbxy0 A==; X-CSE-ConnectionGUID: Id1Xq7AMQDCKhMFWSpzXGA== X-CSE-MsgGUID: Ruse1gmlT6mWYJ29sngNew== X-IronPort-AV: E=McAfee;i="6800,10657,11878"; a="87430104" X-IronPort-AV: E=Sophos;i="6.25,230,1779174000"; d="scan'208";a="87430104" Received: from orviesa009.jf.intel.com ([10.64.159.149]) by orvoesa111.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Aug 2026 23:14:57 -0700 X-CSE-ConnectionGUID: EtJUJCZRQO+QPOocJrxmnw== X-CSE-MsgGUID: clqqQzv4RCOrbqD+WkD+xQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.25,230,1779174000"; d="scan'208";a="265742698" Received: from pgcooper-mobl3.ger.corp.intel.com (HELO localhost) ([10.245.245.209]) by orviesa009-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Aug 2026 23:14:54 -0700 Date: Tue, 18 Aug 2026 09:14:51 +0300 From: Andy Shevchenko To: Jon Hunter Cc: John Ogness , Greg Kroah-Hartman , Jiri Slaby , Andy Shevchenko , Petr Mladek , Sebastian Andrzej Siewior , linux-kernel@vger.kernel.org, Ilpo =?iso-8859-1?Q?J=E4rvinen?= , Hugo Villeneuve , Fushuai Wang , Kees Cook , Stepan Ionichev , linux-serial@vger.kernel.org, "linux-tegra@vger.kernel.org" Subject: Re: [PATCH tty v9 1/2] serial: 8250: Switch to nbcon console, take 2 Message-ID: References: <20260724103654.133654-1-john.ogness@linutronix.de> <20260724103654.133654-2-john.ogness@linutronix.de> <3023d7d7-c8ab-48e7-a0e4-e18cc4ea0b9a@nvidia.com> Precedence: bulk X-Mailing-List: linux-serial@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <3023d7d7-c8ab-48e7-a0e4-e18cc4ea0b9a@nvidia.com> Organization: Intel Finland Oy - BIC 0357606-4 - c/o Alberga Business Park, 6 krs, Bertel Jungin Aukio 5, 02600 Espoo On Tue, Aug 18, 2026 at 06:32:12AM +0100, Jon Hunter wrote: > 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. > > 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. Wasn't v11 applied and not v9? > So far the only > interesting thing I have observed is that if I add 'keep_bootcon' to the > command line the board does boot. keep_bootcon defers driver taking over, that's why it works, it uses just simple primitives instead of full-featured driver. -- With Best Regards, Andy Shevchenko