Messages in this thread | | | Date | Mon, 6 Dec 2021 16:03:42 +0100 | From | Peter Zijlstra <> | Subject | Re: [PATCH 3/4] ACPI: processor idle: Only flush cache on entering C3 |
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On Mon, Dec 06, 2021 at 03:29:51PM +0300, Kirill A. Shutemov wrote: > According to the ACPI spec v6.4, section 8.2, cache flushing required > on entering C3 power state. > > Avoid flushing cache on entering other power states. > > Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> > --- > drivers/acpi/processor_idle.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c > index 76ef1bcc8848..01495aca850e 100644 > --- a/drivers/acpi/processor_idle.c > +++ b/drivers/acpi/processor_idle.c > @@ -567,7 +567,8 @@ static int acpi_idle_play_dead(struct cpuidle_device *dev, int index) > { > struct acpi_processor_cx *cx = per_cpu(acpi_cstate[index], dev->cpu); > > - ACPI_FLUSH_CPU_CACHE(); > + if (cx->type == ACPI_STATE_C3) > + ACPI_FLUSH_CPU_CACHE(); >
acpi_idle_enter() already does this, acpi_idle_enter_s2idle() has it confused again,
Also, I think acpi_idle_enter() does it too late; consider acpi_idle_enter_mb(). Either that or the BM crud needs more comments.
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