From e8775d4aa17d70d123814e68a6a51bbea50e5c16 Mon Sep 17 00:00:00 2001 From: Benjamin Herrenschmidt Date: Fri, 9 Jul 2010 15:30:22 +1000 Subject: [PATCH] powerpc/book3e: Don't re-trigger decrementer on lazy irq restore The decrementer on BookE acts as a level interrupt and doesn't need to be re-triggered when going negative. It doesn't go negative anyways (unless programmed to auto-reload with a negative value) as it stops when reaching 0. Signed-off-by: Benjamin Herrenschmidt --- arch/powerpc/kernel/irq.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/arch/powerpc/kernel/irq.c b/arch/powerpc/kernel/irq.c index 77be3d0..fa6f385 100644 --- a/arch/powerpc/kernel/irq.c +++ b/arch/powerpc/kernel/irq.c @@ -159,8 +159,17 @@ notrace void raw_local_irq_restore(unsigned long en) * use local_paca instead of get_paca() to avoid preemption checking. */ local_paca->hard_enabled = en; + +#ifndef CONFIG_BOOKE + /* On server, re-trigger the decrementer if it went negative since + * some processors only trigger on edge transitions of the sign bit. + * + * BookE has a level sensitive decrementer (latches in TSR) so we + * don't need that + */ if ((int)mfspr(SPRN_DEC) < 0) mtspr(SPRN_DEC, 1); +#endif /* CONFIG_BOOKE */ /* * Force the delivery of pending soft-disabled interrupts on PS3. -- 2.7.4