1 files changed, 36 insertions, 0 deletions
diff --git a/target/linux/brcm2708/patches-4.14/950-0010-irq_bcm2836-Send-event-when-onlining-sleeping-cores.patch b/target/linux/brcm2708/patches-4.14/950-0010-irq_bcm2836-Send-event-when-onlining-sleeping-cores.patch
new file mode 100644
index 0000000000..48ccfbfab4
--- /dev/null
+++ b/target/linux/brcm2708/patches-4.14/950-0010-irq_bcm2836-Send-event-when-onlining-sleeping-cores.patch
@@ -0,0 +1,36 @@
+From 6b8b69ff7c4c25f01535cbe49a80516df6dbcfe8 Mon Sep 17 00:00:00 2001
+From: Phil Elwell <phil@raspberrypi.org>
+Date: Mon, 8 May 2017 16:43:40 +0100
+Subject: [PATCH 010/454] irq_bcm2836: Send event when onlining sleeping cores
+
+In order to reduce power consumption and bus traffic, it is sensible
+for secondary cores to enter a low-power idle state when waiting to
+be started. The wfe instruction causes a core to wait until an event
+or interrupt arrives before continuing to the next instruction.
+The sev instruction sends a wakeup event to the other cores, so call
+it from bcm2836_smp_boot_secondary, the function that wakes up the
+waiting cores during booting.
+
+It is harmless to use this patch without the corresponding change
+adding wfe to the ARMv7/ARMv8-32 stubs, but if the stubs are updated
+and this patch is not applied then the other cores will sleep forever.
+
+See: https://github.com/raspberrypi/linux/issues/1989
+
+Signed-off-by: Phil Elwell <phil@raspberrypi.org>
+---
+ drivers/irqchip/irq-bcm2836.c | 3 +++
+ 1 file changed, 3 insertions(+)
+
+--- a/drivers/irqchip/irq-bcm2836.c
++++ b/drivers/irqchip/irq-bcm2836.c
+@@ -227,6 +227,9 @@ static int __init bcm2836_smp_boot_secon
+ 	writel(secondary_startup_phys,
+ 	       intc.base + LOCAL_MAILBOX3_SET0 + 16 * cpu);
+ 
++	dsb(sy); /* Ensure write has completed before waking the other CPUs */
++	sev();
++
+ 	return 0;
+ }
+