Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755467Ab3IJDxz (ORCPT ); Mon, 9 Sep 2013 23:53:55 -0400 Received: from mail.active-venture.com ([67.228.131.205]:62079 "EHLO mail.active-venture.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755121Ab3IJDxx (ORCPT ); Mon, 9 Sep 2013 23:53:53 -0400 X-Originating-IP: 108.223.40.66 Message-ID: <522E97CE.4070300@roeck-us.net> Date: Mon, 09 Sep 2013 20:53:50 -0700 From: Guenter Roeck User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130803 Thunderbird/17.0.8 MIME-Version: 1.0 To: Stephen Warren CC: Wei Ni , Mark Brown , "khali@linux-fr.org" , "lm-sensors@lm-sensors.org" , "linux-tegra@vger.kernel.org" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH v3 1/2] hwmon: (lm90) Add power control References: <1378722552-10357-1-git-send-email-wni@nvidia.com> <1378722552-10357-2-git-send-email-wni@nvidia.com> <20130909111242.GW29403@sirena.org.uk> <522DB253.6000707@roeck-us.net> <20130909135022.GZ29403@sirena.org.uk> <20130909155043.GA18975@roeck-us.net> <522E9059.3070305@nvidia.com> <522E93D6.2010304@roeck-us.net> <522E94AE.7000804@wwwdotorg.org> In-Reply-To: <522E94AE.7000804@wwwdotorg.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2585 Lines: 59 On 09/09/2013 08:40 PM, Stephen Warren wrote: > On 09/09/2013 09:36 PM, Guenter Roeck wrote: >> On 09/09/2013 08:22 PM, Wei Ni wrote: >>> On 09/09/2013 11:50 PM, Guenter Roeck wrote: >>>> On Mon, Sep 09, 2013 at 02:50:22PM +0100, Mark Brown wrote: >>>>> On Mon, Sep 09, 2013 at 04:34:43AM -0700, Guenter Roeck wrote: >>>>>> On 09/09/2013 04:12 AM, Mark Brown wrote: >>>>>>> On Mon, Sep 09, 2013 at 06:29:11PM +0800, Wei Ni wrote: >>>>> >>>>>>> This doesn't look good, it is going to ignore actual errors - I >>>>>>> *really* >>>>>>> doubt that vcc is optional, it looks like it's the main power >>>>>>> supply for >>>>>>> the device. You should use normal regulator_get(), _optional() is >>>>>>> for >>>>>>> supplies which could physically not be provided in a system (eg, >>>>>>> if the >>>>>>> device can generate them internally if required). >>>>> >>>>>> Then he'll have to make sure that all devicetree files in the system >>>>>> contain references to this regulator. >>>>> >>>>> Or get the patches applied on top of the code that'll be going in this >>>>> cycle implementing get_optional() properly - when that's done the >>>>> default will be to provide a dummy supply for regulator_get(). If you >>>>> ack the patch I'd be happy to carry it. >>>>> >>>> Jean will have to ack it. >>>> >>> I think it's better to use get_optional(), and ignore the errors except >>> -EPROBE_DEFER. Because many platform may always power on this device, >>> and will not provide regulator for it, so if we get errors from >>> regulator subsystem and return it directly, then the probe() can't be >>> implemented, this driver can't work properly, even though it can work >>> without regulator support. >>> Mark, do you mean you have patches for regulator_get_optional() and >>> regulator_get()? >>> >> >> My understanding is that by adding regulator support you essentially >> committed to adding regulators (if necessary dummy ones) for this driver >> to all those platforms. This is quite similar to other drivers in the >> same situation. Once you start along that route, you'll have to go it >> all the way. > > By using regulator_get_optional(), the regulator should be optional, > hence you only have to add it to platforms that need it. > Earlier comments suggest that this is not the intended use case for regulator_get_optional(). Guenter -- 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/