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.you...@imgtec.com>
Cc: Thomas Gleixner <t...@linutronix.de>
Cc: Jason Cooper <ja...@lakedaemon.net>
Cc: linux-kernel@vger.kernel.org
Cc: Andrew Bresticker <abres...@chromium.org>
---
drivers/irqchip/irq-mips-gic.c | 44 +++++++++++++++++++++++++-----------------
1 file changed, 26 insertions(+), 18 deletions(-)
diff --git a/drivers/irqchip/irq-mips-gic.c b/drivers/irqchip/irq-mips-gic.c
index 2b0468e3df6a..f3f9873dfb68 100644
--- a/drivers/irqchip/irq-mips-gic.c
+++ b/drivers/irqchip/irq-mips-gic.c
@@ -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)
--
2.1.0
--
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