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of/irq: of_irq_find_parent: check for parent equal to child 

An interrupt controller may often implicitly inherit itself from a parent
node when in fact the controller is the interrupt root controller. Guard
against the case of child == parent and return NULL in this case.

This can also be fixed by adding an explicit "interrupt-parent;" to a root
interrupt controller node.

Based on code from Grant Likely.

Signed-off-by: Rob Herring <rob.herring@calxeda.com>
Cc: Grant Likely <grant.likely@secretlab.ca>
This commit is contained in:
Rob Herring 2011-09-20 13:02:54 -05:00
parent f910b831c9
commit dc93728084
1 changed files with 7 additions and 7 deletions
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14
drivers/of/irq.c
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@ -58,27 +58,27 @@ EXPORT_SYMBOL_GPL(irq_of_parse_and_map);
*/
struct device_node *of_irq_find_parent(struct device_node *child)
{
struct device_node *p;
struct device_node *p, *c = child;
const __be32 *parp;
if (!of_node_get(child))
if (!of_node_get(c))
return NULL;
do {
parp = of_get_property(child, "interrupt-parent", NULL);
parp = of_get_property(c, "interrupt-parent", NULL);
if (parp == NULL)
p = of_get_parent(child);
p = of_get_parent(c);
else {
if (of_irq_workarounds & OF_IMAP_NO_PHANDLE)
p = of_node_get(of_irq_dflt_pic);
else
p = of_find_node_by_phandle(be32_to_cpup(parp));
}
of_node_put(child);
child = p;
of_node_put(c);
c = p;
} while (p && of_get_property(p, "#interrupt-cells", NULL) == NULL);
return p;
return (p == child) ? NULL : p;
}
/**