1 files changed, 66 insertions, 0 deletions
diff --git a/target/linux/brcm2708/patches-4.19/950-0128-irqchip-irq-bcm2835-Calc.-FIQ_START-at-boot-time.patch b/target/linux/brcm2708/patches-4.19/950-0128-irqchip-irq-bcm2835-Calc.-FIQ_START-at-boot-time.patch
new file mode 100644
index 0000000000..281f273e8d
--- /dev/null
+++ b/target/linux/brcm2708/patches-4.19/950-0128-irqchip-irq-bcm2835-Calc.-FIQ_START-at-boot-time.patch
@@ -0,0 +1,66 @@
+From 3166f055a568c4fe127b70b81a878ab59070a6f5 Mon Sep 17 00:00:00 2001
+From: Phil Elwell <phil@raspberrypi.org>
+Date: Thu, 14 Jun 2018 11:21:04 +0100
+Subject: [PATCH] irqchip: irq-bcm2835: Calc. FIQ_START at boot-time
+
+ad83c7cb2f37 ("irqchip/irq-bcm2836: Add support for DT interrupt polarity")
+changed the way that the BCM2836/7 local interrupts are mapped; instead
+of being pre-mapped they are now mapped on-demand. A side effect of this
+change is that the call to irq_of_parse_and_map from armctrl_of_init
+creates a new mapping, forming a gap between the IRQs and the FIQs. This
+ gap breaks the FIQ<->IRQ mapping which up to now has been done by assuming:
+
+1) that the value of FIQ_START is the same as the number of normal IRQs
+that will be mapped (still true), and
+
+2) that this value is also the offset between an IRQ and its equivalent
+FIQ (which is no longer the case).
+
+Remove both assumptions by measuring the interval between the last IRQ
+and the last FIQ, passing it as the parameter to init_FIQ().
+
+Fixes: https://github.com/raspberrypi/linux/issues/2432
+
+Signed-off-by: Phil Elwell <phil@raspberrypi.org>
+---
+ drivers/irqchip/irq-bcm2835.c | 8 ++++----
+ 1 file changed, 4 insertions(+), 4 deletions(-)
+
+--- a/drivers/irqchip/irq-bcm2835.c
++++ b/drivers/irqchip/irq-bcm2835.c
+@@ -82,8 +82,6 @@
+ #define NR_BANKS		3
+ #define IRQS_PER_BANK		32
+ #define NUMBER_IRQS		MAKE_HWIRQ(NR_BANKS, 0)
+-#undef FIQ_START
+-#define FIQ_START		(NR_IRQS_BANK0 + MAKE_HWIRQ(NR_BANKS - 1, 0))
+ 
+ static const int reg_pending[] __initconst = { 0x00, 0x04, 0x08 };
+ static const int reg_enable[] __initconst = { 0x18, 0x10, 0x14 };
+@@ -211,7 +209,7 @@ static int __init armctrl_of_init(struct
+ 				  bool is_2836)
+ {
+ 	void __iomem *base;
+-	int irq, b, i;
++	int irq = 0, last_irq, b, i;
+ 
+ 	base = of_iomap(node, 0);
+ 	if (!base)
+@@ -237,6 +235,8 @@ static int __init armctrl_of_init(struct
+ 		}
+ 	}
+ 
++	last_irq = irq;
++
+ 	if (is_2836) {
+ 		int parent_irq = irq_of_parse_and_map(node, 0);
+ 
+@@ -267,7 +267,7 @@ static int __init armctrl_of_init(struct
+ 		}
+ 	}
+ #ifndef CONFIG_ARM64
+-	init_FIQ(FIQ_START);
++	init_FIQ(irq - last_irq);
+ #endif
+ 
+ 	return 0;