diff options
authorLinus Walleij <linus.walleij@linaro.org>2013-06-06 12:10:23 +0100
committerGrant Likely <grant.likely@linaro.org>2013-06-08 21:15:09 +0100
commit94a63da0ac1a67bfb8b30aec1086523c5031ea5a (patch)
parent275e31b10ce20613aedceaa5160129c64b260a98 (diff)
irqdomain: document the simple domain first_irq
The first_irq needs to be zero to get a linear domain and that comes with special semantics. We want to simplify this going forward but some documentation never hurts. Signed-off-by: Linus Walleij <linus.walleij@linaro.org> Signed-off-by: Grant Likely <grant.likely@linaro.org>
1 files changed, 4 insertions, 1 deletions
diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c
index 8c4c8ea6a205..54a4d5223238 100644
--- a/kernel/irq/irqdomain.c
+++ b/kernel/irq/irqdomain.c
@@ -143,7 +143,10 @@ static unsigned int irq_domain_legacy_revmap(struct irq_domain *domain,
* irq_domain_add_simple() - Allocate and register a simple irq_domain.
* @of_node: pointer to interrupt controller's device tree node.
* @size: total number of irqs in mapping
- * @first_irq: first number of irq block assigned to the domain
+ * @first_irq: first number of irq block assigned to the domain,
+ * pass zero to assign irqs on-the-fly. This will result in a
+ * linear IRQ domain so it is important to use irq_create_mapping()
+ * for each used IRQ, especially when SPARSE_IRQ is enabled.
* @ops: map/unmap domain callbacks
* @host_data: Controller private data pointer