From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AG47ELseZ1jPguYcfZwKa/Yx6wnVDSevEoogMFB5YlQuVm8IoEz0NpOenXb7Nwp8KyKZr+UoApev ARC-Seal: i=1; a=rsa-sha256; t=1520489193; cv=none; d=google.com; s=arc-20160816; b=GdUBiN1OpT1NchdwLdCiRRGEL5n9xhEfgsBNK5LmsIqfoZiU0gcRYVzbJ1MzQYvGKY U1B1n6e6B8X9Vkrjkmxg+LN603dRrtMzq3OeJt5ID4T01zOB7Rv+D1m+X4+njY7GxRp8 LeUQFJKeHhaY/45kMIMpJo4/saSqeoYlqSMNjtXyi7+0JzhcYKMJeVIdlP+Zcg5TJuG0 vEWr7Ri0GrSKkkv2k2bRauHUlVjnZnIvskfz5i8rbdlDGORwi0w7AeYAHJieHpSja3XK ydktUTMsyBDwO0AXBVndanb5EiM4g7/Qlh3rVNbne6+sIxOFLFwMFGZ/PU0kRvsx/xMq zinA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=content-transfer-encoding:in-reply-to:mime-version:user-agent:date :message-id:from:cc:references:to:subject:arc-authentication-results; bh=zSwvv6xPKPswfUXB7rFZFjzZp91xdXGkhb3HnCZKkKk=; b=jDfRnCzqFABEuCeDXMGsTKT7czJ+6XUpjQTPj+ecZrWDncX3gXCxtItd+g8n0DNViW eCeQma3hnssMG0WcgAnKuotjNUsSMBgQ92s8m1/XXhh42UvsPnfLWmlOM/or1Xf5ovGB PVtxTSOiq0AOwJWRQMnYX50DLo6wjD9jofq88JijWN6NQA6MouQy9ZNy/dgjsdau9OWI /xUvzqZ+FT1kOhpTLlOcxMYbhlt6aqFiGIvqgxyv9ow+fbHVrB+XlMOq4JGcC5Qk/F9J LeZ4sDbW1O6wnK6LV6rK//HA0s8dORV0UqX7oWck1dmJdx4ruCBubqZpkL3N35uk0aUL gmwA== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: domain of ldewangan@nvidia.com designates 216.228.121.64 as permitted sender) smtp.mailfrom=ldewangan@nvidia.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=nvidia.com Authentication-Results: mx.google.com; spf=pass (google.com: domain of ldewangan@nvidia.com designates 216.228.121.64 as permitted sender) smtp.mailfrom=ldewangan@nvidia.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=nvidia.com X-PGP-Universal: processed; by hqpgpgate101.nvidia.com on Wed, 07 Mar 2018 22:06:32 -0800 Subject: Re: [PATCH 05/10] hwmon: generic-pwm-tachometer: Add generic PWM based tachometer To: Guenter Roeck , Rajkumar Rampelli , Mikko Perttunen , , , , , , , , , , , , , , , , , , , , , 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> CC: , , , , , , From: Laxman Dewangan Message-ID: <5bffef40-a4a7-5f7d-a448-b2a381c57822@nvidia.com> Date: Thu, 8 Mar 2018 11:36:24 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.8.0 MIME-Version: 1.0 In-Reply-To: X-Originating-IP: [10.19.64.176] X-ClientProxiedBy: BGMAIL103.nvidia.com (10.25.59.12) To bgmail102.nvidia.com (10.25.59.11) Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 7bit X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1592992898629636853?= X-GMAIL-MSGID: =?utf-8?q?1594348476874419097?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: 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?