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Message-ID: <20111024092411.GE8708@ponder.secretlab.ca>
Date: Mon, 24 Oct 2011 11:24:11 +0200
From: Grant Likely <grant.likely@...retlab.ca>
To: Shawn Guo <shawn.guo@...escale.com>
Cc: Rajendra Nayak <rnayak@...com>,
broonie@...nsource.wolfsonmicro.com, patches@...aro.org,
tony@...mide.com, devicetree-discuss@...ts.ozlabs.org,
linux-kernel@...r.kernel.org, linux-omap@...r.kernel.org,
lrg@...com, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v2 3/5] regulator: helper routine to extract
regulator_init_data
On Fri, Oct 21, 2011 at 04:23:12PM +0800, Shawn Guo wrote:
> On Thu, Oct 20, 2011 at 05:39:32PM +0530, Rajendra Nayak wrote:
> > On Thursday 20 October 2011 11:44 AM, Shawn Guo wrote:
> > >On Thu, Oct 20, 2011 at 10:48:58AM +0530, Rajendra Nayak wrote:
> > >>>Let's look at mc13892-regulator driver. There are 23 regulators defined
> > >>>in array mc13892_regulators. Needless to say, there is a dev behind
> > >>>mc13892-regulator driver. And when getting probed, this driver will
> > >>>call regulator_register() to register those 23 regulators individually.
> > >>>That said, for non-dt world, we have 1 + 23 'dev' with that 1 as the
> > >>>parent of all other 23 'dev' (wrapped by regulator_dev). But with the
> > >>>current DT implementation, we will have at least 1 + 23 * 2 'dev'.
> > >>>These extra 23 'dev' is totally new with DT.
> > >>>
> > >>
> > >>but thats only because the mc13892-regulator driver is implemeted in
> > >>such a way that all the regulators on the platform are bundled in as
> > >>*one* device.
> > >
> > >I did not look into too many regulator drivers, but I expect this is
> > >way that most regulator drivers are implemented in. Having
> > >mc13892-regulator being probed 23 times to register these 23 regulators
> > >just makes less sense to me.
> > >
> > >>It would again depend on how you would pass these from
> > >>the DT, if you indeed stick to the same way of bundling all regulators
> > >>as one device from DT, the mc13892-regulator probe would just get called
> > >>once and there would be one device associated, no?
> > >>
> > >Yes, I indeed would stick to the same way of bundling the registration
> > >of all regulators with mc13892-regulator being probed once. The problem
> > >I have with the current regulator core DT implementation is that it
> > >assumes the device_node of rdev->dev (dev wrapped in regulator_dev) is
> > >being attached to rdev->dev.parent rather than itself. Back to
> > >mc13892-regulator example, that said, it requires the dev of
> > >mc13892-regulator have the device_node of individual regulator attached
> > >to. IOW, the current implementation forces mc13892-regulator to be
> > >probed 23 times to register those 23 regulators. This is wrong to me.
> >
> > I think I now understand to some extent the problem that you seem to be
> > reporting. It is mainly with drivers which bundle all regulators and
> > pass them as one device and would want to do so with DT too.
> >
> > however I am still not clear on how what you seem to suggest would
> > solve this problem. Note that not all drivers do it this way, and
> > there are drivers where each regulator is considered as one device
> > and I suspect they would remain that way with DT too. And hence we
> > need to support both.
> >
> > Do you have any RFC patch/code which could explain better what you are
> > suggesting we do here?
> > >
> Here is what I changed based on your patches. It only changes
> drivers/regulator/core.c.
>
> ---8<-------
> diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
> index 9a5ebbe..8fe132d 100644
> --- a/drivers/regulator/core.c
> +++ b/drivers/regulator/core.c
> @@ -1211,7 +1211,7 @@ static struct regulator *_regulator_get(struct device *dev, const char *id,
> node = of_get_regulator(dev, id);
> if (node)
> list_for_each_entry(rdev, ®ulator_list, list)
> - if (node == rdev->dev.parent->of_node)
> + if (node == rdev->dev.of_node)
> goto found;
> }
> list_for_each_entry(map, ®ulator_map_list, list) {
> @@ -2642,9 +2642,6 @@ struct regulator_dev *regulator_register(struct regulator_desc *regulator_desc,
> regulator_desc->type != REGULATOR_CURRENT)
> return ERR_PTR(-EINVAL);
>
> - if (!init_data)
> - return ERR_PTR(-EINVAL);
> -
> /* Only one of each should be implemented */
> WARN_ON(regulator_desc->ops->get_voltage &&
> regulator_desc->ops->get_voltage_sel);
> @@ -2675,12 +2672,8 @@ struct regulator_dev *regulator_register(struct regulator_desc *regulator_desc,
> INIT_LIST_HEAD(&rdev->list);
> BLOCKING_INIT_NOTIFIER_HEAD(&rdev->notifier);
>
> - /* preform any regulator specific init */
> - if (init_data->regulator_init) {
> - ret = init_data->regulator_init(rdev->reg_data);
> - if (ret < 0)
> - goto clean;
> - }
> + /* find device_node and attach it */
> + rdev->dev.of_node = of_find_node_by_name(NULL, regulator_desc->name);
>
> /* register with sysfs */
> rdev->dev.class = ®ulator_class;
> @@ -2693,6 +2686,20 @@ struct regulator_dev *regulator_register(struct regulator_desc *regulator_desc,
> goto clean;
> }
>
> + if (!init_data) {
> + /* try to get init_data from device tree */
> + init_data = of_get_regulator_init_data(&rdev->dev);
> + if (!init_data)
> + return ERR_PTR(-EINVAL);
> + }
> +
> + /* preform any regulator specific init */
> + if (init_data->regulator_init) {
> + ret = init_data->regulator_init(rdev->reg_data);
> + if (ret < 0)
> + goto clean;
> + }
> +
> dev_set_drvdata(&rdev->dev, rdev);
>
> /* set regulator constraints */
> @@ -2719,7 +2726,7 @@ struct regulator_dev *regulator_register(struct regulator_desc *regulator_desc,
> node = of_get_regulator(dev, supply);
> if (node)
> list_for_each_entry(r, ®ulator_list, list)
> - if (node == r->dev.parent->of_node)
> + if (node == r->dev.of_node)
> goto found;
> }
>
> ------->8---
>
> And my dts file looks like something below.
>
> ecspi@...10000 { /* 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 {
> 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;
> };
>
> ......
> };
To follow up from my earlier comment, this .dts structure looks fine
and reasonable to me, and it would also be fine for the mc13892 driver
to use for_each_child_of_node() to find all the children of the
regulators node. Even finding the 'regulators' node by name from the
mc13892 driver is perfectly fine provided for_each_child_of_node is
used to find it. All of this is okay because it is under the umbrella
of the "fsl,mc13892" binding.
What isn't okay is doing a whole tree search for nodes by name because
there is a high likelyhood of getting a conflict (and yes, I realized
that this example has the device name encoded into the node name, but
that doesn't change the fact that deep searches by name are bad
practice).
g.
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