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powerpc/book3e: Don't re-trigger decrementer on lazy irq restore

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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 <benh@kernel.crashing.org>
This commit is contained in:
Benjamin Herrenschmidt 2010-07-09 15:30:22 +10:00
parent b9f1cd71db
commit e8775d4aa1
1 changed files with 9 additions and 0 deletions
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9
arch/powerpc/kernel/irq.c
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@ -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.