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[108.228.232.20]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-7edc867a2ffsm4251913a12.28.2024.10.27.10.48.37 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 27 Oct 2024 10:48:38 -0700 (PDT) From: "Derek J. Clark" To: Guenter Roeck Cc: Jean Delvare , Jonathan Corbet , Cryolita PukNgae , "Derek J . Clark" , linux-hwmon@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [RFC] hwmon: pwm_enable clarification Date: Sun, 27 Oct 2024 10:48:14 -0700 Message-ID: <20241027174836.8588-1-derekjohn.clark@gmail.com> X-Mailer: git-send-email 2.46.1 Precedence: bulk X-Mailing-List: linux-hwmon@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Greetings all, I am working with Cryolita to fix up the GPD driver she submitted recently: https://lore.kernel.org/all/20240718-gpd_fan-v4-0-116e5431a9fe@gmail.com/ We are currently having a discussion about the meaning of this part of the documentation and are seeking some guidance from upstream. > pwm[1-*]_enable > Fan speed control method: > 0: no fan speed control (i.e. fan at full speed) > 1: manual fan speed control enabled (using pwm[1-*]) > 2+: automatic fan speed control enabled > Check individual chip documentation files for automatic mode > details. > RW In oxp-sensors we took 0 to mean "no kernel control" so a setting of 0 is technically "automatic" but fully controlled by the hardware with no interaction from the driver. In her original driver draft she had taken this literally to have the driver set the fan speed to 100% on this setting rather then give back control to the hardware. My question is simply what is the correct interpretation here? Ideally I would like to see this interface match as existing userspace software is expecting 0 as hardware controlled and 1 as manually controlled, but we also want to ensure this is correct before we submit a v5. Thank you for your time, Derek