Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751796AbaKZJiW (ORCPT ); Wed, 26 Nov 2014 04:38:22 -0500 Received: from mail-wi0-f180.google.com ([209.85.212.180]:58864 "EHLO mail-wi0-f180.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750848AbaKZJiU (ORCPT ); Wed, 26 Nov 2014 04:38:20 -0500 Message-ID: <54759F8A.20303@baylibre.com> Date: Wed, 26 Nov 2014 10:38:18 +0100 From: Benoit Cousson Organization: BayLibre User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.2.0 MIME-Version: 1.0 To: Guenter Roeck , Bartosz Golaszewski CC: LKML , Patrick Titiano Subject: Re: [PATCH 1/5] hwmon: ina2xx: bail-out from ina2xx_probe() in case of configuration errors References: <1416930423-12179-1-git-send-email-bgolaszewski@baylibre.com> <1416930423-12179-2-git-send-email-bgolaszewski@baylibre.com> <5474A72D.2000309@roeck-us.net> <5474B564.9080902@roeck-us.net> <5474C36C.1020004@roeck-us.net> <5474CAC6.8030608@roeck-us.net> <54754364.80705@roeck-us.net> In-Reply-To: <54754364.80705@roeck-us.net> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Guenter, On 26/11/2014 04:05, Guenter Roeck wrote: [...] > Looking into the available documents, I am quite sure that the resistor > is changed by replacing the probe, in other words by pulling the board > with the ina226 and replacing it with another one. Given that, configuring > the shunt resistor value with a sysfs attribute is really the wrong way > to do it; you should use probe specific devicetree overlays instead. Unfortunately, that's not dynamic enough for all the use cases we need to support with the probes. In fact, most customers will rather put the shunts on their board and thus use a shunt-less version of the probe to do the measurement. In that case, there is no way we can hard code, even in a DTS, the shunt value. That's for that kind of usage that we do need to be able to set the shunt value at runtime. The probe in that case can be pluged dynamically on different board jumpers to do the measurement. Later, thanks to the web UI, the user will be able to configure the shunt value based on the way they were plugged to its boards. sysfs seems to be the easiest way to do that. I don't think DT overlay can handle that, since it is depend of the targeted system and not on the measurement system. Thanks, Benoit -- Benoît Cousson BayLibre Embedded Linux Technology Lab www.baylibre.com -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/