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

[Tom Rini]

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.

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;

-- 
Tom
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