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a="84583598" X-IronPort-AV: E=Sophos;i="6.25,163,1779174000"; d="scan'208";a="84583598" Received: from fmviesa001.fm.intel.com ([10.60.135.141]) by orvoesa111.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 13 Jul 2026 22:25:48 -0700 X-CSE-ConnectionGUID: b7VVUikhRGC8aHkOs9IFiw== X-CSE-MsgGUID: Jy/VK4toSbSQTUtrikKzFA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.25,163,1779174000"; d="scan'208";a="280169706" Received: from fdefranc-mobl3.ger.corp.intel.com (HELO localhost) ([10.245.246.248]) by smtpauth.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 13 Jul 2026 22:25:36 -0700 Date: Tue, 14 Jul 2026 08:25:32 +0300 From: Tony Lindgren To: Andy Shevchenko Cc: Tony Lindgren , Praveen Talari , Greg Kroah-Hartman , Jiri Slaby , Ilpo =?iso-8859-1?Q?J=E4rvinen?= , Matthias Brugger , AngeloGioacchino Del Regno , Richard Genoud , Nicolas Ferre , Alexandre Belloni , Claudiu Beznea , Krzysztof Kozlowski , Peter Griffin , Alim Akhtar , Orson Zhai , Baolin Wang , Chunyan Zhang , Patrice Chotard , Maxime Coquelin , Alexandre Torgue , Peter Korsgaard , Michal Simek , Aaro Koskinen , Janusz Krzysztofik , Russell King , Thomas Bogendoerfer , bjorn.andersson@oss.qualcomm.com, Konrad Dybcio , linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org, linux-arm-msm@vger.kernel.org, linux-samsung-soc@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com, linux-omap@vger.kernel.org, linux-mips@vger.kernel.org, Mukesh Kumar Savaliya , aniket.randive@oss.qualcomm.com, chandana.chiluveru@oss.qualcomm.com Subject: Re: [PATCH 0/6] tty: serial: propagate errors from uart_ops.pm callback Message-ID: References: <20260709-add_return_check_for_uart_change_pm-v1-0-e85c6ffa8ec4@oss.qualcomm.com> <20260710043746.GM30058@atomide.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260713_222549_658202_5CC63311 X-CRM114-Status: GOOD ( 24.02 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Mon, Jul 13, 2026 at 02:21:24PM +0300, Andy Shevchenko wrote: > On Mon, Jul 13, 2026 at 12:29:20PM +0300, Tony Lindgren wrote: > > On Fri, Jul 10, 2026 at 07:37:46AM +0300, Tony Lindgren wrote: > > > * Andy Shevchenko [260709 10:38]: > > > > Note, that Tony (you have him in the Cc list) did a lot for some corner cases > > > > with that and we still have them IIRC. Tony, do you know what is the state of > > > > affairs with runtime PM for UART? > > > > > > The RX side of things should work for hardware that can wake up to an incoming > > > event. Linux for sure needs more work to properly handle the various corner case > > > TX wake-up of a PM runtime idled UART. I'm mostly offline until Monday though, > > > will check my notes for more details next week. > > > > For the TX side handling, my understanding is that at least uart_update_mctrl() > > needs to call PM runtime resume and put autosuspend. And we should assume > > uart_update_mctrl() can sleep to resume the PM runtime suspended serial port. > > > > For drivers, the callers of uport->ops->get/set_mctrl() should be updated > > to use uart_update_mctrl() where possible. And the remaining ones that cannot > > sleep should be fixed so they can sleep or have PM runtime disabled. > > > > Anybody have better ideas? > > I don't, but the above sounds like a plan. Is it a big task? I can help with > something in that area, perhaps Ilpo also would be able to participate. Not sure how much changes are involved. Maybe it's safer to set up a runtime PM enabled wrapper for uart_update_mctrl() and then start updating the uart_update_mctrl() and get/set_mctrl() callers one at a time to make them runtime PM aware.