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Fri, 06 Nov 2026 07:16:22 -0800 (PST) Received: from Lord-Beerus.station ([93.146.104.162]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-492d7cc6162sm4124688f8f.47.2026.11.06.07.16.20 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 06 Nov 2026 07:16:21 -0800 (PST) Date: Fri, 6 Nov 2026 16:16:19 +0100 From: Stefano Radaelli To: Johan Hovold Cc: Frank Li , linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, linux-serial@vger.kernel.org, luan.r@variscite.com, alifer.m@variscite.com, pierluigi.p@variscite.com, Stefano Radaelli , Greg Kroah-Hartman , Jiri Slaby , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Peng Fan , Shitalkumar Gandhi , Hugo Villeneuve , Karl Mehltretter , John Ogness , Uwe =?iso-8859-1?Q?Kleine-K=F6nig_=28The_Capable_Hub=29?= , Fugang Duan , linux-pm@vger.kernel.org Subject: Re: [PATCH v1 0/3] serial: Support driver-selected TTY wakeup defaults Message-ID: References: X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Fri, Nov 06, 2026 at 03:00:40PM +0100, Johan Hovold wrote: > On Tue, Nov 03, 2026 at 04:51:24PM +0100, Stefano Radaelli wrote: > > The initial goal was to enable TTY wakeup by default on NXP LPUART ports > > marked with wakeup-source, without requiring a userspace write. Instead > > of keeping this entirely within fsl_lpuart, this series introduces a > > common serial core mechanism that other UART drivers can also adopt. > > > > The new tty_wakeup_default field in struct uart_port lets a driver request > > wakeup to be enabled when its TTY device is registered. Each driver > > decides whether to use it. This series adds wakeup-source to the LPUART > > binding and makes fsl_lpuart the first user, setting the field from that > > property. Other drivers retain their existing behavior, userspace can > > still change power/wakeup, and serdev wakeup policy is unchanged. > > This is a policy decision that should be left for userspace, not > individual drivers. As documented in > Documentation/driver-api/pm/devices.rst: > > The initial value in the :file:`power/wakeup` file is "disabled" > for the majority of devices; the major exceptions are power > buttons, keyboards, and Ethernet adapters whose WoL > (wake-on-LAN) feature has been set up with ethtool. > > So no, this doesn't look like something we want. You should continue > enabling wakeup from userspace on systems that need it instead. > > Note that the "wakeup-source" devicetree attribute also describes > capability, not policy: > > Documentation/devicetree/bindings/power/wakeup-source.txt > Hi Johan, Understood, thanks for clarifying. I incorrectly treated wakeup-source as a request to enable wakeup by default, rather than as a capability description. I will drop this series and keep wakeup enablement in userspace. Thank you, Best Regards, Stefano