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Revert "openpic: Accelerate pending irq search" 

This reverts commit a9bd83f4c65de0058659ede009fa1a241f379edd.

This counting approach is not robust against setting a bit that
was already set, or clearing a bit that was already clear.  Perhaps
that is considered a bug, but besides the lack of any documentation
for that restriction, it's a pretty unpleasant way for the problem
to manifest itself.

It could be made more robust by testing the current value of the
bit before changing the count, but a later patch speeds up IRQ_check
in all cases, not just when there's nothing pending.  Hopefully that
should be adequate to address performance concerns.

Signed-off-by: Scott Wood <scottwood@freescale.com>
Signed-off-by: Alexander Graf <agraf@suse.de>
This commit is contained in:
Scott Wood 2012-12-21 16:15:47 +00:00 committed by Alexander Graf
parent 3c94378e2c
commit 47f73749c6
1 changed files with 0 additions and 11 deletions
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11
hw/openpic.c
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@ -183,7 +183,6 @@ typedef struct IRQQueue {
uint32_t queue[BF_WIDTH(MAX_IRQ)];
int next;
int priority;
int pending; /* nr of pending bits in queue */
} IRQQueue;
typedef struct IRQSource {
@ -269,13 +268,11 @@ typedef struct OpenPICState {
static inline void IRQ_setbit(IRQQueue *q, int n_IRQ)
{
q->pending++;
set_bit(q->queue, n_IRQ);
}
static inline void IRQ_resetbit(IRQQueue *q, int n_IRQ)
{
q->pending--;
reset_bit(q->queue, n_IRQ);
}
@ -291,12 +288,6 @@ static void IRQ_check(OpenPICState *opp, IRQQueue *q)
next = -1;
priority = -1;
if (!q->pending) {
/* IRQ bitmap is empty */
goto out;
}
for (i = 0; i < opp->max_irq; i++) {
if (IRQ_testbit(q, i)) {
DPRINTF("IRQ_check: irq %d set ivpr_pr=%d pr=%d\n",
@ -307,8 +298,6 @@ static void IRQ_check(OpenPICState *opp, IRQQueue *q)
}
}
}
out:
q->next = next;
q->priority = priority;
}