From mboxrd@z Thu Jan  1 00:00:00 1970
From: t-kristo@ti.com (Tero Kristo)
Date: Fri, 24 Feb 2012 15:56:05 +0200
Subject: [PATCH] regulator: twl6030: add support for vdd1, vdd2 and
 vdd3 regulators
In-Reply-To: <20120224132408.GF5450@opensource.wolfsonmicro.com>
References: <1329995109-4795-1-git-send-email-t-kristo@ti.com>
 <20120223153422.GF4553@opensource.wolfsonmicro.com>
 <1330076289.4102.517.camel@sokoban>
 <20120224114940.GB5450@opensource.wolfsonmicro.com>
 <1330089398.4102.539.camel@sokoban>
 <20120224132408.GF5450@opensource.wolfsonmicro.com>
Message-ID: <1330091765.4102.547.camel@sokoban>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

On Fri, 2012-02-24 at 13:24 +0000, Mark Brown wrote:
> On Fri, Feb 24, 2012 at 03:16:38PM +0200, Tero Kristo wrote:
> 
> > I still ain't quite sure how this would work, do you mean adding
> > something like this:
> 
> > +static int twl6030smps_list_voltage(struct regulator_dev *rdev,
> > +                                   unsigned int selector)
> > +{
> > +       return selector;
> > +}
> 
> Yes.
> 
> > I believe this would fail still. I took a look at a few drivers that use
> > regulator_list_voltage(), but all of these seem to numerate voltages
> > based on regulator_count_voltages(), which will return -EINVAL for the
> > SMPS ones as the num_voltages is zero. Also, even if I defined
> > num_voltages here, I would be attempting to list_voltage for zero index,
> > returning zero, but this would be invalid voltage for the cpu obviously
> > (and is also out of range for the regulator min_voltage, and also
> > according to docs invalid return value for the function in the first
> > place.)
> 
> Well, clearly some of the values won't actually be useful and you should
> feel free to return error values for those or apply an offset or
> something but the basic principle applies.

So, do you want me to also change the num_voltages value for the
regulator from zero to be the same as max_uV, as we have this check
within regulator/core:

       if (!ops->list_voltage || selector >= rdev->desc->n_voltages)
                return -EINVAL;

This will also potentially make some code to iterate over regulator
voltages for ~1.5M times. I still don't think adding list_voltage for
the SMPS regulators makes any sense, unless either the API for
regulator_list_voltage is changed, or we change the control for these
regulators completely from set_voltage() based to set_voltage_sel()
based implementation.

-Tero