The decrementer in Book E and 4xx processors interrupts on the
transition from 1 to 0, rather than on the 0 to -1 transition as on
64-bit server and 32-bit "classic" (6xx/7xx/7xxx) processors.
This fixes the problem by making set_dec subtract 1 from the count for
server and classic processors. Since set_dec already had a bunch of
ifdefs to handle different processor types, there is no net increase
in ugliness. :)
This also removes a redundant call to set the decrementer to
0x7fffffff - it was already set to that earlier in timer_interrupt.
Signed-off-by: Paul Mackerras <[EMAIL PROTECTED]>
---
diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c
index 9eb3284..5e253d6 100644
--- a/arch/powerpc/kernel/time.c
+++ b/arch/powerpc/kernel/time.c
@@ -586,7 +586,7 @@ void timer_interrupt(struct pt_regs * regs)
/* not time for this event yet */
now = per_cpu(decrementer_next_tb, cpu) - now;
if (now <= DECREMENTER_MAX)
- set_dec((unsigned int)now - 1);
+ set_dec((int)now);
return;
}
old_regs = set_irq_regs(regs);
@@ -601,10 +601,8 @@ void timer_interrupt(struct pt_regs * regs)
if (evt->event_handler)
evt->event_handler(evt);
- else
- evt->set_next_event(DECREMENTER_MAX, evt);
#ifdef CONFIG_PPC_ISERIES
if (firmware_has_feature(FW_FEATURE_ISERIES) && hvlpevent_is_pending())
@@ -826,9 +824,6 @@ static int decrementer_set_next_event(unsigned long evt,
struct clock_event_device *dev)
{
__get_cpu_var(decrementer_next_tb) = get_tb_or_rtc() + evt;
- /* The decrementer interrupts on the 0 -> -1 transition */
- if (evt)
- --evt;
set_dec(evt);
return 0;
}
diff --git a/include/asm-powerpc/time.h b/include/asm-powerpc/time.h
index f058955..eed64bd 100644
--- a/include/asm-powerpc/time.h
+++ b/include/asm-powerpc/time.h
@@ -183,6 +183,7 @@ static inline void set_dec(int val)
#elif defined(CONFIG_8xx_CPU6)
set_dec_cpu6(val);
#else
+ --val; /* classic decrementer interrupts when dec goes negative */
#ifdef CONFIG_PPC_ISERIES
int cur_dec;
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