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ARM: VFP: re-initialize VFP coprocessor access enables on CPU hotplug 

We can not guarantee that VFP will be enabled when CPU hotplug brings
a CPU back online from a reset state.  Add a hotplug CPU notifier to
ensure that the VFP coprocessor access is enabled whenever a CPU comes
back online.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
Russell King 2010-12-18 10:59:49 +00:00
parent 3705ff6da5
commit 90b44199e8
1 changed files with 23 additions and 1 deletions
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24
arch/arm/vfp/vfpmodule.c
View File

@ -10,9 +10,12 @@
*/
#include <linux/module.h>
#include <linux/types.h>
#include <linux/cpu.h>
#include <linux/kernel.h>
#include <linux/notifier.h>
#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/smp.h>
#include <linux/init.h>
#include <asm/cputype.h>
@ -484,7 +487,24 @@ void vfp_flush_hwstate(struct thread_info *thread)
put_cpu();
}
#include <linux/smp.h>
/*
* VFP hardware can lose all context when a CPU goes offline.
* Safely clear our held state when a CPU has been killed, and
* re-enable access to VFP when the CPU comes back online.
*
* Both CPU_DYING and CPU_STARTING are called on the CPU which
* is being offlined/onlined.
*/
static int vfp_hotplug(struct notifier_block *b, unsigned long action,
void *hcpu)
{
if (action == CPU_DYING || action == CPU_DYING_FROZEN) {
unsigned int cpu = (long)hcpu;
last_VFP_context[cpu] = NULL;
} else if (action == CPU_STARTING || action == CPU_STARTING_FROZEN)
vfp_enable(NULL);
return NOTIFY_OK;
}
/*
* VFP support code initialisation.
@ -514,6 +534,8 @@ static int __init vfp_init(void)
else if (vfpsid & FPSID_NODOUBLE) {
printk("no double precision support\n");
} else {
hotcpu_notifier(vfp_hotplug, 0);
smp_call_function(vfp_enable, NULL, 1);
VFP_arch = (vfpsid & FPSID_ARCH_MASK) >> FPSID_ARCH_BIT; /* Extract the architecture version */