[U-Boot] [PATCH] fdt_support: Fixup 'ethernet' aliases not ending in digits

[Tom Rini <trini@konsulko.com>]

On Sat, Mar 18, 2017 at 08:20:07PM +0200, Tuomas Tynkkynen wrote:
> On Fri, 17 Mar 2017 21:26:51 -0400
> Tom Rini <trini@konsulko.com> wrote:
> 
> > On Fri, Mar 17, 2017 at 09:44:59PM +0200, Tuomas Tynkkynen wrote:
> > 
> > > The Raspberry Pi device tree files since Linux v4.9 have a "ethernet"
> > > alias pointing to the on-board Ethernet device node. However,
> > > U-Boot's fdt_fixup_ethernet() (and the kernel's of_alias_scan()) only
> > > looks at ethernet aliases ending in digits. Make it also check the
> > > "ethernet" alias.
> > > 
> > > Without this Linux isn't told of the MAC address provided by the
> > > RPI firmware and the ethernet device is always assigned a random MAC
> > > address.
> > > 
> > > The device trees themselves can't be fixed as someone is already
> > > depending on the "ethernet" alias:
> > > https://github.com/raspberrypi/firmware/issues/613
> > > 
> > > Signed-off-by: Tuomas Tynkkynen <tuomas@tuxera.com>  
> > 
> > I looked into this a bit and there's a few other (much older) examples
> > of 'ethernet' rather than 'ethernet0' and the spec doesn't mandate
> > aliases end in a number.
> 
> Ah, good to know.
> 
> > That said, looking at the code, I think we can do this in a more clear
> > manner.  Can you test this please?
> > 
> > diff --git a/common/fdt_support.c b/common/fdt_support.c
> > index 55d4d6f6d444..80186a95baf0 100644
> > --- a/common/fdt_support.c
> > +++ b/common/fdt_support.c
> > @@ -482,7 +482,6 @@ void fdt_fixup_ethernet(void *fdt)
> >  	/* Cycle through all aliases */
> >  	for (prop = 0; ; prop++) {
> >  		const char *name;
> > -		int len = strlen("ethernet");
> >  
> >  		/* FDT might have been edited, recompute the offset */
> >  		offset = fdt_first_property_offset(fdt,
> > @@ -495,16 +494,13 @@ void fdt_fixup_ethernet(void *fdt)
> >  			break;
> >  
> >  		path = fdt_getprop_by_offset(fdt, offset, &name, NULL);
> > -		if (!strncmp(name, "ethernet", len)) {
> > +		if (!strncmp(name, "ethernet", 8)) {
> >  			i = trailing_strtol(name);
> > -			if (i != -1) {
> > -				if (i == 0)
> > -					strcpy(mac, "ethaddr");
> > -				else
> > -					sprintf(mac, "eth%daddr", i);
> > -			} else {
> > -				continue;
> > -			}
> > +			/* Handle 'ethernet0' (0) and 'ethernet' (-1) */
> > +			if (i <= 0)
> > +				strcpy(mac, "ethaddr");
> > +			else
> > +				sprintf(mac, "eth%daddr", i);
> >  			tmp = getenv(mac);
> >  			if (!tmp)
> >  				continue;
> > 
> 
> That one accepts everything starting with "ethernet", which sounds undesirable
> if one wants to have e.g. an "ethernet-phy0" alias for some different purpose.

True.  Would you mind doing a v2 of your patch then (and grab my part to
just use the length of ethernet in the strncmp) where we don't add a
comment implying RPi is "wrong" here and just that we sometimes have
"ethernet" as the alias for the first and only ethernet device?  Thanks!

-- 
Tom
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