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irqchip: mips-gic: Handle pending interrupts once in __gic_irq_dispatch() 

When an interrupt occurs __gic_irq_dispatch() continuously reads local
and shared pending registers until all is serviced before
returning. The problem with that is that it could introduce a long
delay before returning if a piece of hardware keeps triggering while
in one of these loops.

To ensure fairness and priority doesn't get skewed a lot, read local
and shared pending registers once to service each pending IRQ once.
If another interupt triggers while servicing the current ones, then we
shall re-enter the handler after we return.

Signed-off-by: Qais Yousef <qais.yousef@imgtec.com>
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: Andrew Bresticker <abrestic@chromium.org>
Cc: <linux-mips@linux-mips.org>
Link: http://lkml.kernel.org/r/1421668289-828-1-git-send-email-qais.yousef@imgtec.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Qais Yousef 2015-01-19 11:51:29 +00:00 committed by Thomas Gleixner
parent 8041dfbd31
commit d7eb4f2ecc
1 changed files with 26 additions and 18 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

44
drivers/irqchip/irq-mips-gic.c
View File

@ -234,9 +234,9 @@ int gic_get_c0_perfcount_int(void)
GIC_LOCAL_TO_HWIRQ(GIC_LOCAL_INT_PERFCTR));
}
static unsigned int gic_get_int(void)
static void gic_handle_shared_int(void)
{
unsigned int i;
unsigned int i, intr, virq;
unsigned long *pcpu_mask;
unsigned long pending_reg, intrmask_reg;
DECLARE_BITMAP(pending, GIC_MAX_INTRS);
@ -258,7 +258,16 @@ static unsigned int gic_get_int(void)
bitmap_and(pending, pending, intrmask, gic_shared_intrs);
bitmap_and(pending, pending, pcpu_mask, gic_shared_intrs);
return find_first_bit(pending, gic_shared_intrs);
intr = find_first_bit(pending, gic_shared_intrs);
while (intr != gic_shared_intrs) {
virq = irq_linear_revmap(gic_irq_domain,
GIC_SHARED_TO_HWIRQ(intr));
do_IRQ(virq);
/* go to next pending bit */
bitmap_clear(pending, intr, 1);
intr = find_first_bit(pending, gic_shared_intrs);
}
}
static void gic_mask_irq(struct irq_data *d)
@ -385,16 +394,26 @@ static struct irq_chip gic_edge_irq_controller = {
#endif
};
static unsigned int gic_get_local_int(void)
static void gic_handle_local_int(void)
{
unsigned long pending, masked;
unsigned int intr, virq;
pending = gic_read(GIC_REG(VPE_LOCAL, GIC_VPE_PEND));
masked = gic_read(GIC_REG(VPE_LOCAL, GIC_VPE_MASK));
bitmap_and(&pending, &pending, &masked, GIC_NUM_LOCAL_INTRS);
return find_first_bit(&pending, GIC_NUM_LOCAL_INTRS);
intr = find_first_bit(&pending, GIC_NUM_LOCAL_INTRS);
while (intr != GIC_NUM_LOCAL_INTRS) {
virq = irq_linear_revmap(gic_irq_domain,
GIC_LOCAL_TO_HWIRQ(intr));
do_IRQ(virq);
/* go to next pending bit */
bitmap_clear(&pending, intr, 1);
intr = find_first_bit(&pending, GIC_NUM_LOCAL_INTRS);
}
}
static void gic_mask_local_irq(struct irq_data *d)
@ -453,19 +472,8 @@ static struct irq_chip gic_all_vpes_local_irq_controller = {
static void __gic_irq_dispatch(void)
{
unsigned int intr, virq;
while ((intr = gic_get_local_int()) != GIC_NUM_LOCAL_INTRS) {
virq = irq_linear_revmap(gic_irq_domain,
GIC_LOCAL_TO_HWIRQ(intr));
do_IRQ(virq);
}
while ((intr = gic_get_int()) != gic_shared_intrs) {
virq = irq_linear_revmap(gic_irq_domain,
GIC_SHARED_TO_HWIRQ(intr));
do_IRQ(virq);
}
gic_handle_local_int();
gic_handle_shared_int();
}
static void gic_irq_dispatch(unsigned int irq, struct irq_desc *desc)