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[82.69.66.36]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-490e2d09a85sm119274065e9.14.2026.06.11.23.53.43 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 11 Jun 2026 23:53:43 -0700 (PDT) Date: Fri, 12 Jun 2026 07:53:42 +0100 From: David Laight To: Ahmad Fatoum Cc: Alexandre Torgue , Maxime Coquelin , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Leonard =?UTF-8?B?R8O2aHJz?= , Marc Kleine-Budde , Alexandre Torgue , devicetree@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, kernel@pengutronix.de Subject: Re: [PATCH 0/3] ARM: dts: stm32: lxa: change stdout-path baud rate from 9600 to 115200 Message-ID: <20260612075342.6615d66c@pumpkin> In-Reply-To: References: <20260611-lxa-stdout-path-baudrate-v1-0-59b60a5069ff@pengutronix.de> <20260611204341.147f1afb@pumpkin> X-Mailer: Claws Mail 4.1.1 (GTK 3.24.38; arm-unknown-linux-gnueabihf) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260611_235347_272958_03982915 X-CRM114-Status: GOOD ( 30.38 ) 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 Thu, 11 Jun 2026 22:33:18 +0200 Ahmad Fatoum wrote: > Hi David, > > On 6/11/26 21:43, David Laight wrote: > > On Thu, 11 Jun 2026 20:12:32 +0200 > > Ahmad Fatoum wrote: > > > >> The LXA boards are the only STM32 boards that set stdout-path = &uart* > >> instead of explicitly specifying a baud rate. > >> > >> This would mean the default of 9600 is used, but it goes unnoticed when > >> booting normally as barebox fixes up a console= line that includes a > >> baud rate. > >> > >> When EFI booting GRUB however, GRUB will not pass along the console= > >> line and thus the board ends up with a 9600 baud Linux console, > >> confusing users. > > > > Is it possible to determine the current baud rate (by reading the hardware > > register) and default to that value. > > Then if grub has initialised the uart the kernel will use the same > > baud rate. > > I think so, yes. In addition to the register divider configuration, one > would need the input clock rate as well, but that's not a problem. > > Do you know if any drivers already do this? I've seen it done somewhere, certainly x86, but possibly NetBSD. That would have been preserving the baud rate set by the bios. You don't want the baud rate changing half way through the boot sequence. David > > Nevertheless, I would like the LXA device trees changed, even if only > to align them with all other existing STM32 device trees. > > Cheers, > Ahmad > > > > > > David > > > >> > >> This series fixes this. As the device trees were added at different > >> times, they are fixed each in a separate commit with its own Fixes: tag. > >> > >> --- > >> Ahmad Fatoum (3): > >> ARM: dts: stm32: lxa-mc1: change stdout-path baud rate from 9600 to 115200 > >> ARM: dts: stm32: lxa-tac: change stdout-path baud rate from 9600 to 115200 > >> ARM: dts: stm32: fairytux2: change stdout-path baud rate from 9600 to 115200 > >> > >> arch/arm/boot/dts/st/stm32mp153c-lxa-fairytux2.dtsi | 2 +- > >> arch/arm/boot/dts/st/stm32mp157c-lxa-mc1.dts | 2 +- > >> arch/arm/boot/dts/st/stm32mp15xc-lxa-tac.dtsi | 2 +- > >> 3 files changed, 3 insertions(+), 3 deletions(-) > >> --- > >> base-commit: 4549871118cf616eecdd2d939f78e3b9e1dddc48 > >> change-id: 20260611-lxa-stdout-path-baudrate-7cf454cdae07 > >> > >> Best regards, > >> -- > >> Ahmad Fatoum > >> > >> > > > > > >