Re: [patch 3/3] clockevents: Fix resume logic - updated version

Andrew Morton
2007-05-11T16:48:29Z

On Thu, 10 May 2007 22:12:07 +0200 "Rafael J. Wysocki" <rjw@sisk.pl> wrote:

> On Thursday, 10 May 2007 11:27, Thomas Gleixner wrote:
> > On Thu, 2007-05-10 at 02:18 -0700, Andrew Morton wrote:
> > > > > > If that patch makes the problem go away, then we should have a quite
> > > > > > good hint what we need to look at.
> > > > >
> > > > > No joy, sorry. It still hangs at the last statement in acpi_evaluate_object().
> > > >
> > > > Can you add "nolapic_timer" to the command line please ?
> > > >
> > >
> > > That works.
> >
> > Ok, that boils it down to the change, which affects the lapic timer
> > resume. It does nothing else, than fiddling in some APIC registers, but
> > I don't see how this affects the ACPI stuff. This smells extremly fishy.
>
> Hmm, I wonder if it might be related to the execution of the _GTS ACPI control
> method in acpi_enter_sleep_state_prep() in violation of the spec.
>
> Andrew, could you please try to apply the following change on top of the
> previous ones and see if the machine still hangs in the same place without
> "nolapic_timer"?
>
> ---
> drivers/acpi/hardware/hwsleep.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> Index: linux-2.6.21/drivers/acpi/hardware/hwsleep.c
> ===================================================================
> --- linux-2.6.21.orig/drivers/acpi/hardware/hwsleep.c
> +++ linux-2.6.21/drivers/acpi/hardware/hwsleep.c
> @@ -200,10 +200,10 @@ acpi_status acpi_enter_sleep_state_prep(
> return_ACPI_STATUS(status);
> }
>
> - status = acpi_evaluate_object(NULL, METHOD_NAME__GTS, &arg_list, NULL);
> + /*status = acpi_evaluate_object(NULL, METHOD_NAME__GTS, &arg_list, NULL);
> if (ACPI_FAILURE(status) && status != AE_NOT_FOUND) {
> return_ACPI_STATUS(status);
> - }
> + }*/
>
> /* Setup the argument to _SST */
>

I tested this against Thomas's original patch (below). Still hangs, in the
same way.

From: Thomas Gleixner <tglx@linutronix.de>

We need to make sure that the clockevent devices are resumed before the
tick is resumed. The current resume logic does not guarantee this.

Add CLOCK_EVT_MODE_RESUME and call the set mode functions of the clock
event devices before resuming the tick / oneshot functionality.

Fixup the existing users.

Fix the PIT handling of CLOCK_EVT_SHUTDOWN by disabling the interrupt
instead of switching to oneshot mode, as this causes slowness on a couple
of systems.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Andi Kleen <ak@suse.de>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

arch/i386/kernel/apic.c | 3 +
arch/i386/kernel/hpet.c | 71 ++-------------------------------
arch/i386/kernel/i8253.c | 43 +++++++++++++------
include/linux/clockchips.h | 1
kernel/time/tick-broadcast.c | 4 +
kernel/time/tick-common.c | 16 ++++---
6 files changed, 51 insertions(+), 87 deletions(-)

diff -puN arch/i386/kernel/apic.c~clockevents-fix-resume-logic-updated-version arch/i386/kernel/apic.c
--- a/arch/i386/kernel/apic.c~clockevents-fix-resume-logic-updated-version
+++ a/arch/i386/kernel/apic.c
@@ -263,6 +263,9 @@ static void lapic_timer_setup(enum clock
v |= (APIC_LVT_MASKED | LOCAL_TIMER_VECTOR);
apic_write_around(APIC_LVTT, v);
break;
+ case CLOCK_EVT_MODE_RESUME:
+ /* Nothing to do here */
+ break;
}

local_irq_restore(flags);
diff -puN arch/i386/kernel/hpet.c~clockevents-fix-resume-logic-updated-version arch/i386/kernel/hpet.c
--- a/arch/i386/kernel/hpet.c~clockevents-fix-resume-logic-updated-version
+++ a/arch/i386/kernel/hpet.c
@@ -187,6 +187,10 @@ static void hpet_set_mode(enum clock_eve
cfg &= ~HPET_TN_ENABLE;
hpet_writel(cfg, HPET_T0_CFG);
break;
+
+ case CLOCK_EVT_MODE_RESUME:
+ hpet_enable_int();
+ break;
}
}

@@ -217,6 +221,7 @@ static struct clocksource clocksource_hp
.mask = HPET_MASK,
.shift = HPET_SHIFT,
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
+ .resume = hpet_start_counter,
};

/*
@@ -291,7 +296,6 @@ int __init hpet_enable(void)

clocksource_register(&clocksource_hpet);

-
if (id & HPET_ID_LEGSUP) {
hpet_enable_int();
hpet_reserve_platform_timers(id);
@@ -524,68 +528,3 @@ irqreturn_t hpet_rtc_interrupt(int irq,
return IRQ_HANDLED;
}
#endif
-
-
-/*
- * Suspend/resume part
- */
-
-#ifdef CONFIG_PM
-
-static int hpet_suspend(struct sys_device *sys_device, pm_message_t state)
-{
- unsigned long cfg = hpet_readl(HPET_CFG);
-
- cfg &= ~(HPET_CFG_ENABLE|HPET_CFG_LEGACY);
- hpet_writel(cfg, HPET_CFG);
-
- return 0;
-}
-
-static int hpet_resume(struct sys_device *sys_device)
-{
- unsigned int id;
-
- hpet_start_counter();
-
- id = hpet_readl(HPET_ID);
-
- if (id & HPET_ID_LEGSUP)
- hpet_enable_int();
-
- return 0;
-}
-
-static struct sysdev_class hpet_class = {
- set_kset_name("hpet"),
- .suspend = hpet_suspend,
- .resume = hpet_resume,
-};
-
-static struct sys_device hpet_device = {
- .id = 0,
- .cls = &hpet_class,
-};
-
-
-static __init int hpet_register_sysfs(void)
-{
- int err;
-
- if (!is_hpet_capable())
- return 0;
-
- err = sysdev_class_register(&hpet_class);
-
- if (!err) {
- err = sysdev_register(&hpet_device);
- if (err)
- sysdev_class_unregister(&hpet_class);
- }
-
- return err;
-}
-
-device_initcall(hpet_register_sysfs);
-
-#endif
diff -puN arch/i386/kernel/i8253.c~clockevents-fix-resume-logic-updated-version arch/i386/kernel/i8253.c
--- a/arch/i386/kernel/i8253.c~clockevents-fix-resume-logic-updated-version
+++ a/arch/i386/kernel/i8253.c
@@ -3,11 +3,11 @@
*
*/
#include <linux/clockchips.h>
-#include <linux/spinlock.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
#include <linux/jiffies.h>
-#include <linux/sysdev.h>
#include <linux/module.h>
-#include <linux/init.h>
+#include <linux/spinlock.h>

#include <asm/smp.h>
#include <asm/delay.h>
@@ -26,6 +26,24 @@ EXPORT_SYMBOL(i8253_lock);
*/
struct clock_event_device *global_clock_event;

+/* Status of the PIT interrupt */
+static int pit_irq_disabled;
+
+/*
+ * Control pit interrupt enable / disable
+ */
+static void pit_control_irq(int disable)
+{
+ if (pit_irq_disabled == disable)
+ return;
+
+ pit_irq_disabled = disable;
+ if (disable)
+ disable_irq(0);
+ else
+ enable_irq(0);
+}
+
/*
* Initialize the PIT timer.
*
@@ -42,26 +60,23 @@ static void init_pit_timer(enum clock_ev
case CLOCK_EVT_MODE_PERIODIC:
/* binary, mode 2, LSB/MSB, ch 0 */
outb_p(0x34, PIT_MODE);
- udelay(10);
outb_p(LATCH & 0xff , PIT_CH0); /* LSB */
- udelay(10);
outb(LATCH >> 8 , PIT_CH0); /* MSB */
+ pit_control_irq(0);
break;

- /*
- * Avoid unnecessary state transitions, as it confuses
- * Geode / Cyrix based boxen.
- */
case CLOCK_EVT_MODE_SHUTDOWN:
- if (evt->mode == CLOCK_EVT_MODE_UNUSED)
- break;
case CLOCK_EVT_MODE_UNUSED:
- if (evt->mode == CLOCK_EVT_MODE_SHUTDOWN)
- break;
+ pit_control_irq(1);
+ break;
case CLOCK_EVT_MODE_ONESHOT:
/* One shot setup */
outb_p(0x38, PIT_MODE);
- udelay(10);
+ pit_control_irq(0);
+ break;
+
+ case CLOCK_EVT_MODE_RESUME:
+ /* Nothing to do here */
break;
}
spin_unlock_irqrestore(&i8253_lock, flags);
diff -puN include/linux/clockchips.h~clockevents-fix-resume-logic-updated-version include/linux/clockchips.h
--- a/include/linux/clockchips.h~clockevents-fix-resume-logic-updated-version
+++ a/include/linux/clockchips.h
@@ -23,6 +23,7 @@ enum clock_event_mode {
CLOCK_EVT_MODE_SHUTDOWN,
CLOCK_EVT_MODE_PERIODIC,
CLOCK_EVT_MODE_ONESHOT,
+ CLOCK_EVT_MODE_RESUME,
};

/* Clock event notification values */
diff -puN kernel/time/tick-broadcast.c~clockevents-fix-resume-logic-updated-version kernel/time/tick-broadcast.c
--- a/kernel/time/tick-broadcast.c~clockevents-fix-resume-logic-updated-version
+++ a/kernel/time/tick-broadcast.c
@@ -292,7 +292,7 @@ void tick_suspend_broadcast(void)
spin_lock_irqsave(&tick_broadcast_lock, flags);

bc = tick_broadcast_device.evtdev;
- if (bc && tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)
+ if (bc)
clockevents_set_mode(bc, CLOCK_EVT_MODE_SHUTDOWN);

spin_unlock_irqrestore(&tick_broadcast_lock, flags);
@@ -309,6 +309,8 @@ int tick_resume_broadcast(void)
bc = tick_broadcast_device.evtdev;

if (bc) {
+ clockevents_set_mode(bc, CLOCK_EVT_MODE_RESUME);
+
switch (tick_broadcast_device.mode) {
case TICKDEV_MODE_PERIODIC:
if(!cpus_empty(tick_broadcast_mask))
diff -puN kernel/time/tick-common.c~clockevents-fix-resume-logic-updated-version kernel/time/tick-common.c
--- a/kernel/time/tick-common.c~clockevents-fix-resume-logic-updated-version
+++ a/kernel/time/tick-common.c
@@ -318,12 +318,17 @@ static void tick_resume(void)
{
struct tick_device *td = &__get_cpu_var(tick_cpu_device);
unsigned long flags;
+ int broadcast = tick_resume_broadcast();

spin_lock_irqsave(&tick_device_lock, flags);
- if (td->mode == TICKDEV_MODE_PERIODIC)
- tick_setup_periodic(td->evtdev, 0);
- else
- tick_resume_oneshot();
+ clockevents_set_mode(td->evtdev, CLOCK_EVT_MODE_RESUME);
+
+ if (!broadcast) {
+ if (td->mode == TICKDEV_MODE_PERIODIC)
+ tick_setup_periodic(td->evtdev, 0);
+ else
+ tick_resume_oneshot();
+ }
spin_unlock_irqrestore(&tick_device_lock, flags);
}

@@ -360,8 +365,7 @@ static int tick_notify(struct notifier_b
break;

case CLOCK_EVT_NOTIFY_RESUME:
- if (!tick_resume_broadcast())
- tick_resume();
+ tick_resume();
break;

default:
_