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[v3,2/6] irqchip/realtek-rtl: fix off-by-one in routing

Message ID 177b920aa8d8610615692d0e657e509f363c85ca.1641739718.git.sander@svanheule.net
State Accepted
Commit 91351b5dd0fd494eb2d85e1bb6aca77b067447e0
Headers show
Series Rework realtek-rtl IRQ driver | expand

Commit Message

Sander Vanheule Jan. 9, 2022, 2:54 p.m. UTC
There is an offset between routing values (1..6) and the connected MIPS
CPU interrupts (2..7), but no distinction was made between these two
values.

This issue was previously hidden during testing, because an interrupt
mapping was used where for each required interrupt another (unused)
routing was configured, with an offset of +1.

Offset the CPU IRQ numbers by -1 to retrieve the correct routing value.

Fixes: 9f3a0f34b84a ("irqchip: Add support for Realtek RTL838x/RTL839x interrupt controller")
Signed-off-by: Sander Vanheule <sander@svanheule.net>
---
 drivers/irqchip/irq-realtek-rtl.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)
diff mbox series

Patch

diff --git a/drivers/irqchip/irq-realtek-rtl.c b/drivers/irqchip/irq-realtek-rtl.c
index d6788dd93c7b..568614edd88f 100644
--- a/drivers/irqchip/irq-realtek-rtl.c
+++ b/drivers/irqchip/irq-realtek-rtl.c
@@ -95,7 +95,8 @@  static void realtek_irq_dispatch(struct irq_desc *desc)
  * SoC interrupts are cascaded to MIPS CPU interrupts according to the
  * interrupt-map in the device tree. Each SoC interrupt gets 4 bits for
  * the CPU interrupt in an Interrupt Routing Register. Max 32 SoC interrupts
- * thus go into 4 IRRs.
+ * thus go into 4 IRRs. A routing value of '0' means the interrupt is left
+ * disconnected. Routing values {1..15} connect to output lines {0..14}.
  */
 static int __init map_interrupts(struct device_node *node, struct irq_domain *domain)
 {
@@ -134,7 +135,7 @@  static int __init map_interrupts(struct device_node *node, struct irq_domain *do
 		of_node_put(cpu_ictl);
 
 		cpu_int = be32_to_cpup(imap + 2);
-		if (cpu_int > 7)
+		if (cpu_int > 7 || cpu_int < 2)
 			return -EINVAL;
 
 		if (!(mips_irqs_set & BIT(cpu_int))) {
@@ -143,7 +144,8 @@  static int __init map_interrupts(struct device_node *node, struct irq_domain *do
 			mips_irqs_set |= BIT(cpu_int);
 		}
 
-		regs[(soc_int * 4) / 32] |= cpu_int << (soc_int * 4) % 32;
+		/* Use routing values (1..6) for CPU interrupts (2..7) */
+		regs[(soc_int * 4) / 32] |= (cpu_int - 1) << (soc_int * 4) % 32;
 		imap += 3;
 	}