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powerpc: Fix PowerMac IRQ handling bug

PATCH New Benjamin Herrenschmidt 1 participant 1 message Aug 31, 2006

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PowerPC Linux for power macintosh
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Benjamin Herrenschmidt

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PATCH 1/1 powerpc: Fix PowerMac IRQ handling bug

The port to genirq & the new powerpc interrupt model in 2.6.18 introduced a bug in the legacy PowerMac PIC code (used on older machines) because of a typo potentially causing hangs due to interrupt storms. This fixes it, along with a performance issue causing us to do spurrious retriggers after masking an interrupt.

Signed-off-by Benjamin Herrenschmidt <[email protected]>

---
This is another 2.6.18 regression, please apply to 2.6.18

arch/powerpc/platforms/powermac/pic.c +3 -3
Index: linux-work/arch/powerpc/platforms/powermac/pic.c
===================================================================
@@ -87,8 +87,8 @@ static void __pmac_retrigger(unsigned in
 static void pmac_mask_and_ack_irq(unsigned int virq)
 {
 	unsigned int src = irq_map[virq].hwirq;
-        unsigned long bit = 1UL << (virq & 0x1f);
-        int i = virq >> 5;
+        unsigned long bit = 1UL << (src & 0x1f);
+        int i = src >> 5;
         unsigned long flags;
 
 	spin_lock_irqsave(&pmac_pic_lock, flags);

@@ -175,7 +175,7 @@ static void pmac_mask_irq(unsigned int v
 
   	spin_lock_irqsave(&pmac_pic_lock, flags);
         __clear_bit(src, ppc_cached_irq_mask);
-        __pmac_set_irq_mask(src, 0);
+        __pmac_set_irq_mask(src, 1);
   	spin_unlock_irqrestore(&pmac_pic_lock, flags);
 }