From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755049Ab3F1Ouo (ORCPT ); Fri, 28 Jun 2013 10:50:44 -0400 Received: from mail.free-electrons.com ([94.23.35.102]:60603 "EHLO mail.free-electrons.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751558Ab3F1Oum (ORCPT ); Fri, 28 Jun 2013 10:50:42 -0400 Message-ID: <51CDA2BF.5050501@free-electrons.com> Date: Fri, 28 Jun 2013 16:50:39 +0200 From: Alexandre Belloni Organization: Free Electrons User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130623 Thunderbird/17.0.7 MIME-Version: 1.0 To: Lars-Peter Clausen CC: Guenter Roeck , Maxime Ripard , Shawn Guo , Jean Delvare , jimwall@q.com, brian@crystalfontz.com, Grant Likely , Rob Herring , Rob Landley , Russell King , devicetree-discuss@lists.ozlabs.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, lm-sensors@lm-sensors.org, linux-arm-kernel@lists.infradead.org, linux-iio@vger.kernel.org Subject: Re: [PATCH 3/4] hwmon: Add a simple driver to read the MXS SoC temperature References: <1372236673-20725-1-git-send-email-alexandre.belloni@free-electrons.com> <1372236673-20725-4-git-send-email-alexandre.belloni@free-electrons.com> <20130626143927.GB31998@roeck-us.net> <20130627091732.GP5803@lukather> <20130627142758.GA5812@roeck-us.net> <51CC91E8.50605@free-electrons.com> <51CD9B19.90407@metafoo.de> In-Reply-To: <51CD9B19.90407@metafoo.de> X-Enigmail-Version: 1.4.6 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 28/06/2013 16:18, Lars-Peter Clausen wrote: > On 06/27/2013 09:26 PM, Alexandre Belloni wrote: >> >> They are already registered as IIO_TEMP but only implement read_raw. Also, >> >> iio_hwmon_read_val() is using iio_read_channel_processed() and that will >> basically only read one of the 2 channels. As I documented, you actually >> need to read both channel 8 and channel 9 and then compute the value in >> Kelvins. I'm not sure how you want me to do that in the current framework. > What are these two channels actually measuring? Is the value of a single > channel meaningful on it's own? If not it might make sense to update the IIO > driver to just have one temperature channel. It's not actually meaningful on its own. So, what you would do is expose one iio channel for two ADC channels and do the computation in read_raw ? or read_processed ? Then using iio-hwon to export it. ? Regards, -- Alexandre Belloni, Free Electrons Embedded Linux, Kernel and Android engineering http://free-electrons.com