This two-line patch adds the "sev" instruction required to wake the
secondary cores, should they be sleeping in a "wfe" instruction.
It applies on top of Eric's bcm2835-soc-smp-cleanup branch[1], after
Stefan's patchset moving the SMP startup code out of the irqchip
driver.
[1] - https://github.com/anholt/linux/commits/bcm2835-soc-smp-cleanup
Phil Elwell (1):
ARM: bcm2836: Send event when onlining other cores
arch/arm/mach-bcm/platsmp.c | 3 +++
1 file changed, 3 insertions(+)
--
1.9.1
Secondary cores should 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, and
the "sev" instruction sends a wakeup event to the other cores.
Add an "sev" (and a memory barrier) to bcm2836_boot_secondary, the
function that wakes the waiting cores during booting. This is required
if the secondary cores are sitting in "wfe", and harmless if not.
Signed-off-by: Phil Elwell <[email protected]>
---
arch/arm/mach-bcm/platsmp.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/arch/arm/mach-bcm/platsmp.c b/arch/arm/mach-bcm/platsmp.c
index 3fa1a99..7811160 100644
--- a/arch/arm/mach-bcm/platsmp.c
+++ b/arch/arm/mach-bcm/platsmp.c
@@ -312,6 +312,9 @@ static int bcm2836_boot_secondary(unsigned int cpu, struct task_struct *idle)
writel(virt_to_phys(secondary_startup),
intc_base + LOCAL_MAILBOX3_SET0 + 16 * cpu);
+ dsb(sy);
+ sev();
+
iounmap(intc_base);
return 0;
--
1.9.1
On 08/08/2017 04:04 AM, Phil Elwell wrote:
> Secondary cores should 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, and
> the "sev" instruction sends a wakeup event to the other cores.
>
> Add an "sev" (and a memory barrier) to bcm2836_boot_secondary, the
> function that wakes the waiting cores during booting. This is required
> if the secondary cores are sitting in "wfe", and harmless if not.
Eric, should I just pick this up for the upcoming ARM SoC pull requests
that I am preparing, or do you have more changes aside from the two tags
I already merged?
Thanks!
>
> Signed-off-by: Phil Elwell <[email protected]>
> ---
> arch/arm/mach-bcm/platsmp.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/arch/arm/mach-bcm/platsmp.c b/arch/arm/mach-bcm/platsmp.c
> index 3fa1a99..7811160 100644
> --- a/arch/arm/mach-bcm/platsmp.c
> +++ b/arch/arm/mach-bcm/platsmp.c
> @@ -312,6 +312,9 @@ static int bcm2836_boot_secondary(unsigned int cpu, struct task_struct *idle)
> writel(virt_to_phys(secondary_startup),
> intc_base + LOCAL_MAILBOX3_SET0 + 16 * cpu);
>
> + dsb(sy);
> + sev();
> +
> iounmap(intc_base);
>
> return 0;
>
--
Florian
Hi Florian,
> Florian Fainelli <[email protected]> hat am 14. August 2017 um 18:25 geschrieben:
>
>
>
>
> On 08/08/2017 04:04 AM, Phil Elwell wrote:
> > Secondary cores should 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, and
> > the "sev" instruction sends a wakeup event to the other cores.
> >
> > Add an "sev" (and a memory barrier) to bcm2836_boot_secondary, the
> > function that wakes the waiting cores during booting. This is required
> > if the secondary cores are sitting in "wfe", and harmless if not.
>
> Eric, should I just pick this up for the upcoming ARM SoC pull requests
> that I am preparing, or do you have more changes aside from the two tags
> I already merged?
this patch depends on series "ARM: bcm2836: Move SMP startup code to arch/arm".
I didn't had the time to test Phil's patch in all relevant cases. But i could at least prepare a branch with my changes with the acks.
Stefan
>
> Thanks!
>
> >
> > Signed-off-by: Phil Elwell <[email protected]>
> > ---
> > arch/arm/mach-bcm/platsmp.c | 3 +++
> > 1 file changed, 3 insertions(+)
> >
> > diff --git a/arch/arm/mach-bcm/platsmp.c b/arch/arm/mach-bcm/platsmp.c
> > index 3fa1a99..7811160 100644
> > --- a/arch/arm/mach-bcm/platsmp.c
> > +++ b/arch/arm/mach-bcm/platsmp.c
> > @@ -312,6 +312,9 @@ static int bcm2836_boot_secondary(unsigned int cpu, struct task_struct *idle)
> > writel(virt_to_phys(secondary_startup),
> > intc_base + LOCAL_MAILBOX3_SET0 + 16 * cpu);
> >
> > + dsb(sy);
> > + sev();
> > +
> > iounmap(intc_base);
> >
> > return 0;
> >
>
> --
> Florian
Hi Eric,
> Stefan Wahren <[email protected]> hat am 14. August 2017 um 19:11 geschrieben:
>
>
> Hi Florian,
>
> > Florian Fainelli <[email protected]> hat am 14. August 2017 um 18:25 geschrieben:
> >
> >
> >
> >
> > On 08/08/2017 04:04 AM, Phil Elwell wrote:
> > > Secondary cores should 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, and
> > > the "sev" instruction sends a wakeup event to the other cores.
> > >
> > > Add an "sev" (and a memory barrier) to bcm2836_boot_secondary, the
> > > function that wakes the waiting cores during booting. This is required
> > > if the secondary cores are sitting in "wfe", and harmless if not.
> >
> > Eric, should I just pick this up for the upcoming ARM SoC pull requests
> > that I am preparing, or do you have more changes aside from the two tags
> > I already merged?
>
> this patch depends on series "ARM: bcm2836: Move SMP startup code to arch/arm".
>
> I didn't had the time to test Phil's patch in all relevant cases. But i could at least prepare a branch with my changes with the acks.
i prepared the branches bcm2835-dt-next-v2 and bcm2835-soc-next.
Stefan
Stefan Wahren <[email protected]> writes:
> Hi Eric,
>
>> Stefan Wahren <[email protected]> hat am 14. August 2017 um 19:11 geschrieben:
>>
>>
>> Hi Florian,
>>
>> > Florian Fainelli <[email protected]> hat am 14. August 2017 um 18:25 geschrieben:
>> >
>> >
>> >
>> >
>> > On 08/08/2017 04:04 AM, Phil Elwell wrote:
>> > > Secondary cores should 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, and
>> > > the "sev" instruction sends a wakeup event to the other cores.
>> > >
>> > > Add an "sev" (and a memory barrier) to bcm2836_boot_secondary, the
>> > > function that wakes the waiting cores during booting. This is required
>> > > if the secondary cores are sitting in "wfe", and harmless if not.
>> >
>> > Eric, should I just pick this up for the upcoming ARM SoC pull requests
>> > that I am preparing, or do you have more changes aside from the two tags
>> > I already merged?
>>
>> this patch depends on series "ARM: bcm2836: Move SMP startup code to arch/arm".
>>
>> I didn't had the time to test Phil's patch in all relevant cases. But i could at least prepare a branch with my changes with the acks.
>
> i prepared the branches bcm2835-dt-next-v2 and bcm2835-soc-next.
bcm2835-soc-next on its own breaks boot for me on the Pi2, so I had to
merge in the DT branch first. I've rebased to do that, pulled in this
patch (and the clk one), and sent PRs for -dt and -soc.