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SubjectRe: [PATCH] of/base: Fix PowerPC address parsing hack
What about this one instead ? I want to cache it because that function
can be called quite a while and doing two additional property lookup
and string compares every time might hurt some platforms.


We have a historical hack that treats missing ranges properties as the
equivalent of an empty one. This is needed for ancient PowerMac "bad"
device-trees, and shouldn't be enabled for any other PowerPC platform,
otherwise we get some nasty layout of devices in sysfs or even
duplication when a set of otherwise identically named devices is
created multiple times under a different parent node with no ranges

This fix is needed for the PowerNV i2c busses to be exposed properly
and will fix a number of other embedded cases.

Signed-off-by: Benjamin Herrenschmidt <>
CC: <>

diff --git a/drivers/of/address.c b/drivers/of/address.c
index e371825..5eae0cd 100644
--- a/drivers/of/address.c
+++ b/drivers/of/address.c
@@ -403,6 +403,17 @@ static struct of_bus *of_match_bus(struct device_node *np)
return NULL;

+static int of_empty_ranges_quirk(void)
+ /* To save cycles, we cache the result */
+ static int quirk_state = -1;
+ if (quirk_state < 0)
+ quirk_state = of_machine_is_compatible("Power Macintosh") ||
+ of_machine_is_compatible("MacRISC");
+ return quirk_state;
static int of_translate_one(struct device_node *parent, struct of_bus *bus,
struct of_bus *pbus, __be32 *addr,
int na, int ns, int pna, const char *rprop)
@@ -428,12 +439,10 @@ static int of_translate_one(struct device_node *parent, struct of_bus *bus,
* This code is only enabled on powerpc. --gcl
ranges = of_get_property(parent, rprop, &rlen);
-#if !defined(CONFIG_PPC)
- if (ranges == NULL) {
+ if (ranges == NULL && !of_empty_ranges_quirk()) {
pr_err("OF: no ranges; cannot translate\n");
return 1;
-#endif /* !defined(CONFIG_PPC) */
if (ranges == NULL || rlen == 0) {
offset = of_read_number(addr, na);
memset(addr, 0, pna * 4);

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