From mboxrd@z Thu Jan 1 00:00:00 1970 From: Laxman Dewangan Subject: Re: [PATCH 05/10] hwmon: generic-pwm-tachometer: Add generic PWM based tachometer Date: Thu, 8 Mar 2018 11:36:24 +0530 Message-ID: <5bffef40-a4a7-5f7d-a448-b2a381c57822@nvidia.com> References: <1519196339-9377-1-git-send-email-rrajk@nvidia.com> <1519196339-9377-6-git-send-email-rrajk@nvidia.com> <5172edff-fe29-7ed1-f0d2-b0359ea2c24d@roeck-us.net> <2510b525-ec36-b49d-5a62-81f335c0d10d@nvidia.com> <2628eff2-dd33-34f4-a7e1-cfe46ef88a3f@nvidia.com> <4556a8d2-947d-72c4-2962-3167afb53978@kapsi.fi> <62ba7f67-5a99-51ab-1214-eb68ebb7e642@roeck-us.net> <952cb50e-d9a0-ae5e-d9f6-d1ce268f0384@nvidia.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=m.gmane.org@lists.infradead.org To: Guenter Roeck , Rajkumar Rampelli , Mikko Perttunen , robh+dt@kernel.org, mark.rutland@arm.com, thierry.reding@gmail.com, jonathanh@nvidia.com, jdelvare@suse.com, corbet@lwn.net, catalin.marinas@arm.com, will.deacon@arm.com, kstewart@linuxfoundation.org, gregkh@linuxfoundation.org, pombredanne@nexb.com, mmaddireddy@nvidia.com, mperttunen@nvidia.com, arnd@arndb.de, timur@codeaurora.org, andy.gross@linaro.org, xuwei5@hisilicon.com, elder@linaro.org, heiko@sntech.de, krzk@kernel.org, ard.biesheuvel@linaro.org Cc: linux-hwmon@vger.kernel.org, devicetree@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-pwm@vger.kernel.org, linux-tegra@vger.kernel.org, linux-arm-kernel@lists.infradead.org List-Id: linux-tegra@vger.kernel.org On Wednesday 07 March 2018 07:50 PM, Guenter Roeck wrote: > On 03/07/2018 01:47 AM, Rajkumar Rampelli wrote: >> >>> >>> While I am not opposed to ABI changes, the merits of those would >>> need to be >>> discussed on the mailing list. But replacing "fan1_input" with "rpm" is >>> not an acceptable ABI change, even if it may measure something that >>> turns >>> but isn't a fan. >>> >>> If this _is_ in fact supposed to be used for something else but >>> fans, we >>> would have to discuss what that might be, and if hwmon is the >>> appropriate >>> subsystem to measure and report it. This does to some degree lead >>> back to >>> my concern of having the "fan" part of this patch series in the pwm >>> core. >>> I am still not sure if that makes sense. >>> >>> Thanks, >>> Guenter >> I am planning to add tachometer support in pwm-fan.c driver >> (drivers/hwmon/) instead of adding new generic-pwm-tachometer.c >> driver. Measuring RPM value will be done in pwm-fan driver itself >> using pwm capture feature and will add new sysfs attributes under >> this driver to report rpm value of fan. > > There is an existing attribute to report the RPM of fans. It is called > fan[1..n]_input. > > "replacing "fan1_input" with "rpm" is not an acceptable ABI change" > > Preemptive NACK. The RPM is measured speed via PWM signal capture which is output from fan. So should we have the fan[1..n]_output_rpm?