No change in functionality.
Clarify that the only difference between level triggered and
edge triggered interrupts is on the leading edge.
Signed-off-by: Matthew Ogilvie <mmogilvi_qemu@xxxxxxxxxxxx>
---
arch/x86/kvm/i8259.c | 28 +++++++++++-----------------
1 file changed, 11 insertions(+), 17 deletions(-)
diff --git a/arch/x86/kvm/i8259.c b/arch/x86/kvm/i8259.c
index 76d8dc1..63f731b 100644
--- a/arch/x86/kvm/i8259.c
+++ b/arch/x86/kvm/i8259.c
@@ -95,26 +95,20 @@ static inline int pic_set_irq1(struct kvm_kpic_state *s, int irq, int level)
{
int mask, ret = 1;
mask = 1 << irq;
- if (s->elcr & mask) /* level triggered */
- if (level) {
+ if (level) {
+ if ((s->last_irr & mask) == 0 || /* edge for edge-triggered */
+ (s->elcr & mask)) { /* or level triggered */
ret = !(s->irr & mask);
s->irr |= mask;
- s->last_irr |= mask;
- } else {
- s->irr &= ~mask;
- s->last_irr &= ~mask;
- }
- else /* edge triggered */
- if (level) {
- if ((s->last_irr & mask) == 0) {
- ret = !(s->irr & mask);
- s->irr |= mask;
- }
- s->last_irr |= mask;
- } else {
- s->irr &= ~mask;
- s->last_irr &= ~mask;
}
+ s->last_irr |= mask;
+ } else {
+ /* Dropping level clears the interrupt regardless of edge
+ * trigger vs level trigger.
+ */
+ s->irr &= ~mask;
+ s->last_irr &= ~mask;
+ }
return (s->imr & mask) ? -1 : ret;
}
--
1.7.10.2.484.gcd07cc5
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