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Commit d7eb4f2e authored by Qais Yousef's avatar Qais Yousef Committed by Thomas Gleixner
Browse files

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: default avatarQais 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: default avatarThomas Gleixner <tglx@linutronix.de>
parent 8041dfbd

drivers/irqchip/irq-mips-gic.c

+26 −18
Original line number Diff line number Diff line
@@ -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)