Re: [PATCH v3] of/base: Fix PowerPC address parsing hack
From: Grant Likely <hidden>
Date: 2014-11-18 17:00:12
Also in:
linux-devicetree, lkml
On Fri, 14 Nov 2014 17:55:03 +1100 , Benjamin Herrenschmidt [off-list ref] wrote:
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@kernel.crashing.org> CC: <redacted>
Acked-by: Grant Likely <redacted> Rob will pick up this patch and send it to Linus in his fixups tree for v3.18 g.
quoted hunk ↗ jump to hunk
--- V2: Make it less horrendously ugly V3: use IS_ENABLED() drivers/of/address.c | 19 ++++++++++++++++--- 1 file changed, 16 insertions(+), 3 deletions(-)diff --git a/drivers/of/address.c b/drivers/of/address.c index e371825..42e416a 100644 --- a/drivers/of/address.c +++ b/drivers/of/address.c@@ -403,6 +403,21 @@ static struct of_bus *of_match_bus(struct device_node *np) return NULL; } +static int of_empty_ranges_quirk(void) +{ + if (IS_ENABLED(CONFIG_PPC)) { + /* 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; + } + return false; +} + 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 +443,10 @@ 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);