From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Warren Subject: Re: [PATCH v3 1/2] hwmon: (lm90) Add power control Date: Tue, 10 Sep 2013 12:37:47 -0600 Message-ID: <522F66FB.2000608@wwwdotorg.org> References: <20130909155043.GA18975@roeck-us.net> <522E9059.3070305@nvidia.com> <522E93D6.2010304@roeck-us.net> <522E94AE.7000804@wwwdotorg.org> <522E97CE.4070300@roeck-us.net> <522E9C84.9070405@wwwdotorg.org> <20130910100939.GW29403@sirena.org.uk> <522F35BF.6070909@wwwdotorg.org> <20130910170438.GS29403@sirena.org.uk> <522F5A65.8040907@wwwdotorg.org> <20130910181837.GD29403@sirena.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20130910181837.GD29403-GFdadSzt00ze9xe1eoZjHA@public.gmane.org> Sender: linux-tegra-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Mark Brown Cc: Guenter Roeck , Wei Ni , "khali-PUYAD+kWke1g9hUCZPvPmw@public.gmane.org" , "lm-sensors-GZX6beZjE8VD60Wz+7aTrA@public.gmane.org" , "linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" List-Id: linux-tegra@vger.kernel.org On 09/10/2013 12:18 PM, Mark Brown wrote: > On Tue, Sep 10, 2013 at 11:44:05AM -0600, Stephen Warren wrote: > >> OK, so I believe you're saying that the case of a chip with just >> a single power source, which absolutely must be present in HW for >> the chip to be powered, isn't appropriate for >> regulator_get_optional(). Something must always define a >> regulator for that power source, even if there is no external SW >> control over that power source. > > Well, it really should be mandatory - personally I don't think > it's sensible to add off-SoC chips without defining their > regulators, it's more trouble than it's worth to have to add them > later for all the time it takes to define the bindings. In IETF > terms it's a should. > >> We either allow the regulator to be optional (since SW control >> over the regulator is optional), or go back to every board file >> and DT and add a dummy regulator in (which then breaks DT ABI, >> and even ignoring that is a pain). > > The whole point of the way I'm changing the dummy support is to > allow us to gracefully cope with errors here so there's no > mandatory update even though strictly there should be one. OK, so for the DT binding we should make vcc-supply a required property, yet the driver will still work OK if that property just happens to be missing (or e.g. when instantiated from a board file, and there's no regulator).