On Thu, Nov 13, 2014 at 12:45 AM, Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx> wrote: > 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 > property. > > 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 <benh@xxxxxxxxxxxxxxxxxxx> > CC: <stable@xxxxxxxxxxxxxxx> How far back does this need to go? I assume I need to get this in for v3.18. > > 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 (IS_ENABLED(CONFIG_POWERPC)) { > + if (quirk_state < 0) > + quirk_state = of_machine_is_compatible("Power Macintosh") || > + of_machine_is_compatible("MacRISC"); > + return quirk_state; } return 0; So it gets compiled out for non powerpc. > +} > + > 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); > > -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html