Hello.
Paul Mackerras wrote:
> 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]>
Heh, I have alike patch but refrained from posting being busy with other
stuff and nt having any PPC target at hand... so, I'm late as usual
> ---
> 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 */
I got an impression that set_dec_cpu6() needs the decremented val as well.
Plus for iSeries compiler will complain for iSeries about cur_dec being
declared after val-- statement, C++ style. How about such variant (and the
same for <asm-ppc/time.h>)?
Index: powerpc/include/asm-powerpc/time.h
===================================================================
--- powerpc.orig/include/asm-powerpc/time.h
+++ powerpc/include/asm-powerpc/time.h
@@ -178,16 +178,24 @@ static inline unsigned int get_dec(void)
static inline void set_dec(int val)
{
+ /*
+ * The "classic" decrementer interrupts at 0 to -1 transition, while
+ * 40x and book E decrementers interrupt at 1 to 0 transition.
+ */
#if defined(CONFIG_40x)
mtspr(SPRN_PIT, val);
-#elif defined(CONFIG_8xx_CPU6)
+#else
+#if !defined(CONFIG_BOOKE)
+ val = val ? val - 1 : 0;
+#endif
+#if defined(CONFIG_8xx_CPU6)
set_dec_cpu6(val);
-#ifdef CONFIG_PPC_ISERIES
- int cur_dec;
-
+#if defined(CONFIG_PPC_ISERIES)
if (firmware_has_feature(FW_FEATURE_ISERIES) &&
- get_lppaca()->shared_proc) {
+ get_lppaca()->shared_proc) {
+ int cur_dec;
+
get_lppaca()->virtual_decr = val;
cur_dec = get_dec();
if (cur_dec > val)
@@ -195,7 +203,8 @@ static inline void set_dec(int val)
} else
#endif
mtspr(SPRN_DEC, val);
-#endif /* not 40x or 8xx_CPU6 */
+#endif /* not 8xx_CPU6 */
+#endif /* not 40x */
}
static inline unsigned long tb_ticks_since(unsigned long tstamp)
WBR, Sergei
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