Re: [PATCH 2/3] usb: otg: add device tree support to otg library

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On Thu, Sep 06, 2012 at 05:30:02PM +0300, Felipe Balbi wrote:
> On Tue, Sep 04, 2012 at 09:32:06PM +0200, Marc Kleine-Budde wrote:
> > On 09/04/2012 07:51 PM, ABRAHAM, KISHON VIJAY wrote:
> > >>>>>>>>>>> Since it's already a common function, we may give phandler property
> > >>>>>>>>>>> a common name too. So we will not need phandle argument.
> > >>>>>>>>>>> Please also don't forget to document the devm_xxx and dt binding.
> > >>>>>>>>>>
> > >>>>>>>>>> I don't think this is a good idea. If we hardcode the phandle name, we
> > >>>>>>>>>> introduce a limit of one phy per usb device. The usb3 controllers
> > >>>>>>>>>> alreadyt use two phys (one for usb2, the othere for usb3) for one
> > >>>>>>>>>> controller. So I think we should not make the same mistake again.
> > >>>>>>>> That only means current binding is not good enough. Rather not, means
> > >>>>>>>> it should not be in common code.
> > >>>>>>>> Maybe something like:
> > >>>>>>>> usbport0-phys = <&phy0>;
> > >>>>>>>> usbport1-phys = <&phy1 &phy2>; /* usb2 & usb3 */
> > >>>>>>>
> > >>>>>>> Granted. Do we need strings that describe the phys, like in pinctrl or
> > >>>>>>> is a index enough? What about this?
> > >>>>>>>
> > >>>>>>> struct usb_phy *devm_usb_get_phy_by_phandle(struct device *dev,
> > >>>>>>>   int index)
> > >>>>>>>
> > >>>>>>
> > >>>>>> Comments? The phandle_name string will be "usbphy".
> > >>>>>
> > >>>>> I don't think phandle_name should be usbphy. Eventually we want to turn
> > >>>>> this into a kernel-wide phy subsystem and if we use usbphy, we will just
> > >>>>> have to patch a bunch of dts files once we make the move.
> > >>> Coud you please give a link of "kernel-wide phy subsystem" discussion?
> > >>>>
> > >>>> Is just "phy" better?
> > >>> If the property name don't include port number, how do we know what
> > >>> port the phy is attached to?
> > > 
> > > We can use something like "xxxx-phy" as the phandle name. And the
> > > users can get the phy by using
> > > devm_usb_get_phy_by_phandle(dev, "xxxx").
> > > (So the frwrk appends *-phy* to the name and searches). Or we don't
> > > have any  restriction on the phandle naming conventions and search for
> > > the phandle by the name the user passes in devm_usb_get_phy_by_phandle
> > > directly.
> > 
> > Maintainer, I need a Maintainer. Can someone please decide what we want
> > to have here. I can code all that, but please someone has to make a
> > decision. Now, please.
> 
> Like I said on another reply:
> 
> phyN (phy1, phy2, ... phyN) is better since eventually we want to turn
> this into a kernel-wide PHY layer.
I think Marc is wondering how to handle the below two case in such way.
 - how to get the port number the phy is attached to
 - how to describe it if a port has two phys.

Thanks
Richard
> 
> -- 
> balbi


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