Re: [PATCH 6/7] dt-bindings: net: bgmac: add bindings documentation for bgmac

[Ray Jui]

On 7/1/2016 8:42 AM, Arnd Bergmann wrote:
> On Friday, July 1, 2016 11:17:25 AM CEST Jon Mason wrote:
> > On Fri, Jul 1, 2016 at 5:46 AM, Arnd Bergmann <arnd@xxxxxxxx> wrote:
> > > On Thursday, June 30, 2016 6:59:13 PM CEST Jon Mason wrote:
> > > > +
> > > > +Required properties:
> > > > + - compatible: "brcm,bgmac-nsp"
> > > > + - reg:                Address and length of the GMAC registers,
> > > > +               Address and length of the GMAC IDM registers
> > > > + - reg-names:  Names of the registers.  Must have both "gmac_base" and
> > > > +               "idm_base"
> > > > + - interrupts: Interrupt number
> > > > +
> > >
> > >
> > > "brcm,bgmac-nsp" sounds a bit too general. As I understand, this is a family
> > > of SoCs that might not all have the exact same implementation of this
> > > ethernet device, as we can see from the long lookup table in bgmac_probe().
> >
> > The Broadcom iProc family of SoCs contains:
> > Northstar
> > Northstar Plus
> > Cygnus
> > Northstar 2
> > a few SoCs that are under development
> > and a number of ethernet switches (which might never be officially supported)
> >
> > Each one of these SoCs could have a different revision of the gmac IP
> > block, but they should be uniform within each SoC (though there might
> > be a A0/B0 change necessary).  The Northstar Plus product family has a
> > number of different implementations, but the SoC is unchanged.  So, I
> > think this might be too specific, when we really need a general compat
> > string.
>
> Ok, thanks for the clarification, that sounds good enough.
>
> > Broadcom has a history of sharing IP blocks amongst the different
> > divisions.  So, this driver might be used on other SoC families (as it
> > apparently has been done in the past, based on the code you
> > reference).  I do not know of any way to know what legacy, non-iProc
> > chips have used this IP block.  I can make this "brcm,iproc-bgmac",
> > and add "brcm,iproc-nsp-bgmac" as an alternative compatible string in
> > this file (which I believe you are suggesting), but there might be
> > non-iProc SoCs that use this driver.  Is this acceptable?
>
> If it is also used outside of iProc, then I see no need for the
> extra compatible string, although it would not do any harm either.
>
> Ideally we should name it whatever the name for this IP block is
> inside of the company, with "nsp" as the designation for the variant
> in Northstar Plus. A lot of Broadcom IP blocks themselves seem to have
> some four-digit or five-digit number, maybe this one does too?
>
> 	Arnd

Note this IP block has an official IP controller name of "amac" from the 
ASIC team.

Thanks,

Ray