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* Re: [PATCH v2 3/5] regulator: helper routine to extract regulator_init_data
From: Shawn Guo @ 2011-10-24 14:51 UTC (permalink / raw)
  To: Grant Likely
  Cc: Mark Brown, Rajendra Nayak, patches, tony, devicetree-discuss,
	linux-kernel, linux-omap, lrg, linux-arm-kernel
In-Reply-To: <20111024135950.GV8708@ponder.secretlab.ca>

On Mon, Oct 24, 2011 at 03:59:50PM +0200, Grant Likely wrote:
> On Mon, Oct 24, 2011 at 09:40:26PM +0800, Shawn Guo wrote:
> > On Mon, Oct 24, 2011 at 03:06:37PM +0200, Mark Brown wrote:
> > > On Mon, Oct 24, 2011 at 09:04:31PM +0800, Shawn Guo wrote:
> > > 
> > > > If we can attach the device_node of 'regulators' node to dev->of_node
> > > > when calling regulator_register(regulator_desc, dev, ...) from
> > > > regulator driver, the regulator core will be able to find all nodes under
> > > > 'regulators' using for_each_child_of_node(dev->of_node, child).
> > > 
> > > Please provide concrete examples of the bindings you're talking about,
> > > the really important thing here is how sane the bindings look and I've
> > > really got no idea what any of what you're talking about will look like
> > > or if they make sense.
> > > 
> > The only thing different from what I attached last time is the
> > compatible string added to 'regulators' node.
> > 
> >         ecspi@70010000 { /* ECSPI1 */
> >                 fsl,spi-num-chipselects = <2>;
> >                 cs-gpios = <&gpio3 24 0>, /* GPIO4_24 */
> >                            <&gpio3 25 0>; /* GPIO4_25 */
> >                 status = "okay";
> > 
> >                 pmic: mc13892@0 {
> >                         #address-cells = <1>;
> >                         #size-cells = <0>;
> >                         compatible = "fsl,mc13892";
> >                         spi-max-frequency = <6000000>;
> >                         reg = <0>;
> >                         mc13xxx-irq-gpios = <&gpio0 8 0>; /* GPIO1_8 */
> > 
> >                         regulators {
> >                         	compatible = "fsl,mc13892-regulator";
> > 
> >                                 sw1reg: mc13892_sw1 {
> >                                         regulator-min-uV = <600000>;
> >                                         regulator-max-uV = <1375000>;
> >                                         regulator-change-voltage;
> >                                         regulator-boot-on;
> >                                         regulator-always-on;
> >                                 };
> > 
> >                                 sw2reg: mc13892_sw2 {
> >                                         regulator-min-uV = <900000>;
> >                                         regulator-max-uV = <1850000>;
> >                                         regulator-change-voltage;
> >                                         regulator-boot-on;
> >                                         regulator-always-on;
> >                                 };
> > 
> >                                 ......
> >                         };
> > 
> >                         leds {
> >                                 ......
> >                         };
> > 
> >                         buttons {
> >                                 ......
> >                         };
> >                 };
> > 
> >                 flash: at45db321d@1 {
> >                         ......
> >                 };
> >         };
> > 
> > > > hesitate to hack this into mfd_add_devices(), so I would like to add
> > > > compatible string "fsl,mc13892-regulators" to node 'regulators' and
> > > > find the node using of_find_compatible_node(dev->parent, NULL,
> > > > "fsl,mc13892-regulators").
> > > 
> > > It's not immediately obvious to me that having a binding for the
> > > regulators separately makes sense, it's not a usefully distinct device.
> > > 
> > Fair point.  Actually, I also hate to have the finding of node
> > 'regulators' plugged into regulator driver.  What about following
> > change to address Grant's concern on global device tree search?
> >  
> > diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
> > index 8fe132d..29dcf90 100644
> > --- a/drivers/regulator/core.c
> > +++ b/drivers/regulator/core.c
> > @@ -2673,7 +2673,8 @@ struct regulator_dev *regulator_register(struct regulator_desc *regulator_desc,
> >         BLOCKING_INIT_NOTIFIER_HEAD(&rdev->notifier);
> > 
> >         /* find device_node and attach it */
> > -       rdev->dev.of_node = of_find_node_by_name(NULL, regulator_desc->name);
> > +       rdev->dev.of_node = of_find_node_by_name(dev->parent->of_node,
> > +                                                regulator_desc->name);
> 
> of_find_node_by_name() doesn't work that way.  The first argument is a
> starting point, but it doesn't restrict the search to children of a
> node.
> 
> for_each_child_of_node() is what you want to use when iterating over
> the children which unfortunately changes the structure of this
> function.
> 
The dev->parent->of_node is meant to point to node 'pmic: mc13892@0'.
And the intention here is not to iterate over the children, but to
start a search from a reasonable point rather than the top root node.

-- 
Regards,
Shawn


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