You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
37 lines
1.3 KiB
Diff
37 lines
1.3 KiB
Diff
6 years ago
|
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;
|
||
|
|
}
|
||
|
|
|