diff options
Diffstat (limited to 'target/linux/brcm2708/patches-4.14/950-0010-irq_bcm2836-Send-event-when-onlining-sleeping-cores.patch')
-rw-r--r-- | target/linux/brcm2708/patches-4.14/950-0010-irq_bcm2836-Send-event-when-onlining-sleeping-cores.patch | 36 |
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; + } + |