Re: [PATCH 1/2] phy: usbphy: Add dt documentation for Broadcom Cygnus USB PHY driver

[Arun Ramamurthy]

Hello Alan and Arnd

I wanted to follow up on this patch and ascertain what I would have to 
change. Please see below for my questions

On 15-02-18 04:46 PM, Arun Ramamurthy wrote:
> On 15-02-18 07:15 AM, Arnd Bergmann wrote:
> > On Tuesday 17 February 2015 13:05:50 Arun Ramamurthy wrote:
> > > On 15-02-17 12:53 PM, Arnd Bergmann wrote:
> > > > On Tuesday 17 February 2015 12:00:49 Arun Ramamurthy wrote:
> > > > > Arnd, I patched the ehci and ohci driver to accept multiple phys so
> > > > > they
> > > > > require different names and cannot both be "usb". That patch was
> > > > > accepted by Alen Stern but I did not update the bindings
> > > > > documentation.
> > > > > I will send out another patch for that. Could we go with the naming
> > > > > scheme of "usb" + "p" + port number or do you have other suggestions?
> > > >
> > > > I don't have a good idea, but I think it would be best if the first
> > > > phy could remain named "usb" for compatibility with the existing
> > > > binding.
> > > The patch was written in a way that all the existing and new drivers can
> > > continue to use "usb" if they are using only one phy so that we remain
> > > compatible. The names need to be different only if more than one phy is
> > > specified. In such cases i don't think the first phy should be "usb" as
> > > it would be confusing to have
> > >          phy-names = "usb","usbp1"
> >
> > I see your patch now, as 7e7a0e67f2c ("usb: ehci-platform: add support
> > for
> > multiple phys per controller"), and I'm not too happy about the way you
> > did this.
>
> > We already concluded that there should have been a binding change
> > to go along with this, and that would have caught the fact that you
> > circumvent the API here by reading the phy names manually. That
> > part should never have made it into the kernel.
> >
> > I think we can do this either by defining specific names for the
> > phy, or by changing the generic PHY binding to allow anonymous
> > phy references (leaving out "phy-names" entirely), and adding a
> > proper API for that.
> Thanks Arnd, I will wait for Alan's comments before proceeding. I am
> happy to patch the ehci-platform driver to use a new api instead of
> devm_phy_get if that is the best option.
>
> > > Should I run this by Alan Stern?
> >
> > I've added him to Cc here. He clearly didn't know the background about
> > the DT binding change, and should not need to, but he may have an opinion
> > on what names we should use.
Arnd, should I re patch the ehci-platform driver to avoid phy-names 
entirely? Alan, if not do you have an opinion on what the usb phy names 
should be? The current patch uses "usbp" + port number such as "usbp0" , 
"usbp1" etc

> > > > What is the reason for having two phys in your case? Are these
> > > > identical phy devices connected to a single controller or do they
> > > > server different purposes?
> > > Yes, we have three identical phys connected to a single host controller
> > > and one of the phys is also connected to the device controller
> >
> > Ok, no problem with that, let's just make sure we come up with a
> > good binding for it.
Arnd do you have any other comments on the phy driver itself? Thank you
> >     Arnd
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