Re: [PATCH v5 1/6] drivers: phy: add generic PHY framework

[Kishon Vijay Abraham I]

Hi,

On Wednesday 03 April 2013 07:57 PM, Felipe Balbi wrote:
> hi,
>
> On Wed, Apr 03, 2013 at 07:48:42PM +0530, Kishon Vijay Abraham I wrote:
> > > > +struct phy *of_phy_xlate(struct phy *phy, struct of_phandle_args *args)
> > > > +{
> > > > +	return phy;
> > > > +}
> > > > +EXPORT_SYMBOL_GPL(of_phy_xlate);
> > >
> > > so you get a PHY and just return it ? What gives ?? (maybe I skipped
> > > some of the discussion...)
> >
> > hmm.. this is for the common case where the PHY provider implements
> > only one PHY. And both phy provider and phy_instance is represented
> > by struct phy *.
> >
> > For the case where PHY provider implements multiple PHYs (here it
> > will have a single dt node), the PHY provider will implement it's own
> > version of of_xlate that takes *of_phandle_args* as argument and
> > finds the appropriate PHY.
>
> got it.
>
> > > > +struct phy *of_phy_get(struct device *dev, int index)
> > > > +{
> > > > +	int ret;
> > > > +	struct phy *phy = NULL;
> > > > +	struct phy_bind *phy_map = NULL;
> > > > +	struct of_phandle_args args;
> > > > +	struct device_node *node;
> > > > +
> > > > +	if (!dev->of_node) {
> > > > +		dev_dbg(dev, "device does not have a device node entry\n");
> > > > +		return ERR_PTR(-EINVAL);
> > > > +	}
> > > > +
> > > > +	ret = of_parse_phandle_with_args(dev->of_node, "phys", "#phy-cells",
> > > > +		index, &args);
> > > > +	if (ret) {
> > > > +		dev_dbg(dev, "failed to get phy in %s node\n",
> > > > +			dev->of_node->full_name);
> > > > +		return ERR_PTR(-ENODEV);
> > > > +	}
> > > > +
> > > > +	phy = of_phy_lookup(args.np);
> > > > +	if (IS_ERR(phy) || !try_module_get(phy->ops->owner)) {
> > > > +		phy = ERR_PTR(-EPROBE_DEFER);
> > > > +		goto err0;
> > > > +	}
> > > > +
> > > > +	phy = phy->ops->of_xlate(phy, &args);
> > >
> > > alright, so of_xlate() is optional, am I right ? How about not
> >
> > Not really. of_xlate is mandatory (it's even checked in phy_create).
> > Either the PHY provider can implement it's own version or use the
> > implementation above (by filling the function pointer).
>
> alright.
>
> > > implementing the above and have a check for of_xlate() being a valid
> > > pointer here ?
> >
> > Having the way it is actually mandates the PHY providers to always
> > provide of_xlate which IMO is better since some PHY providers wont
> > accidentally be using the default implementation.
>
> ok cool, thanks for clarifying.
>
> > > > +		ret = -EINVAL;
> > > > +		goto err0;
> > > > +	}
> > > > +
> > > > +	if (!phy_class)
> > > > +		phy_core_init();
> > >
> > > why don't you setup the class on module_init ? Then this would be a
> > > terrible error condition here :-)
> >
> > This is for the case where the PHY driver gets loaded before the PHY
> > framework. I could have returned EPROBE_DEFER here instead I thought
> > will have it this way.
>
> looks a bit weird IMO. Is it really possible for PHY to load before ?

yeah. it actually happened when I tried with beagle and had all the 
modules as built-in. Because twl4030 has subsys_initcall(), it loads 
before PHY framework.

Thanks
Kishon
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/