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SubjectRe: [PATCH v4 1/4] drivers: usb: phy: add a new driver for usb part of control module
Hi,

On Fri, Jan 25, 2013 at 04:14:02PM +0000, Mark Rutland wrote:
> On Fri, Jan 25, 2013 at 02:59:28PM +0000, Felipe Balbi wrote:
> > Hi,
> >
> > On Fri, Jan 25, 2013 at 12:29:43PM +0000, Mark Rutland wrote:
> > > > > > + depending upon omap4 or omap5.
> > > > > > + - reg-names: The names of the register addresses corresponding to the registers
> > > > > > + filled in "reg".
> > > > > > + - ti,type: This is used to differentiate whether the control module has
> > > > > > + usb mailbox or usb3 phy power. omap4 has usb mailbox in control module to
> > > > > > + notify events to the musb core and omap5 has usb3 phy power register to
> > > > > > + power on usb3 phy. Should be "1" if it has mailbox and "2" if it has usb3
> > > > > > + phy power.
> > > > >
> > > > > Why not make this a string property, perhaps values "mailbox" or "register"?
> > > >
> > > > NAK.
> > >
> > > Can I ask what your objection to using a string property is?
> > >
> > > As far as I can see, "ti,type" is only used by this driver, so there's no
> > > common convention to stick to. Using a string makes the binding easier for
> > > humans to read, and thus harder to mess up in a dts, and it decouples the
> > > binding from kernel-side constants.
> >
> > IIRC there is some work going on to add #define-like support for DT,
> > which would allow us to match against integers while still having
> > meaningful symbolic representations.
>
> I was under the impression that the motivation for using the preprocessor on
> the DT was to allow symbolic names for device/soc-specific values like
> addresses, rather than what amounts to ABI values for the binding.
>
> I don't see the point in building a binding that depends on future
> functionality to be legible, especially as we can make it more readable,
> robust, and just as extensible today, with a simple change to the proposed
> binding.
>
> Even ignoring the above, the driver isn't doing appropriate sanity checking.
> If you use a string property, this sanity check is implicit in the parsing --
> you've either matched a value you can handle or you haven't.

Even IRQs use numbers (not talking about the IRQ number, but the IRQ
flags), why would we depend on string comparisson ? It doesn't make
sense.

--
balbi
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