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

[Tuomas Tynkkynen]

On Fri, 17 Mar 2017 21:26:51 -0400
Tom Rini <trini at 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 at 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.