Re: [PATCH v4 1/6] drivers: phy: add generic PHY framework

[Kishon Vijay Abraham I]

On Tuesday 02 April 2013 09:10 PM, Stephen Warren wrote:
> On 04/02/2013 02:37 AM, Kishon Vijay Abraham I wrote:
> > Hi,
> >
> > On Thursday 28 March 2013 09:15 PM, Stephen Warren wrote:
> > > On 03/27/2013 11:43 PM, Kishon Vijay Abraham I wrote:
> > > > The PHY framework provides a set of APIs for the PHY drivers to
> > > > create/destroy a PHY and APIs for the PHY users to obtain a reference
> > > > to the
> > >
> > > > diff --git a/Documentation/devicetree/bindings/phy/phy-bindings.txt
>
> > > > +PHY subsystem refer Documentation/phy.txt
> > > > +
> > > > +PHY device node
> > > > +===============
> > > > +
> > > > +Optional Properties:
> > > > +#phy-cells:    Number of cells in a PHY specifier;  The meaning of all those
> > > > +        cells is defined by the binding for the phy node. However
> > > > +        in-order to return the correct PHY, the PHY susbsystem
> > > > +        requires the first cell always refers to the port.
> > >
> > > Why impose that restriction? Other DT bindings do not.
> > >
> > > This is typically implemented by having each provider driver implement a
> > > .of_xlate() operation, which parses all of the specifier cells, and
> > > returns the ID of the object it represents. This allows bindings to use
> > > whatever arbitrary representation they want.
> >
> > Do you mean something like this
> >
> > struct phy *of_phy_get(struct device *dev, int index)
> > {
> >      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);
> >      }
>
> Looks good.
>
> > //Here we have to get a reference to the phy in order to call of_xlate
> > which seems a little hacky to me. I'm not sure how else can we call the
> > provider driver :-(
> >      phy = of_phy_lookup(dev, node);
> >      if (IS_ERR(phy) || !try_module_get(phy->ops->owner)) {
> >          phy = ERR_PTR(-EPROBE_DEFER);
> >          goto err0;
> >      }
>
> I think the concept of a "PHY provider" and a "PHY instance" are different.
>
> of_xlate should be called on a "PHY provider", and return a "PHY
> instance". Hence, above you want to only look up a "PHY provider", so
> there's no hackiness involved.

Cool. That makes it a lot clearer.

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/