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Commit 9ece8839 authored by Evgeniy Dushistov's avatar Evgeniy Dushistov Committed by Jason Cooper
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ARM: orion: Fix for certain sequence of request_irq can cause irq storm 



The problem is that hardware handled by arm/plat-orion/gpio.c,
require ack for edge irq, and no ack for level irq.

The code handle this issue, by two "struct irq_chip_type" per
one "struct irq_chip_generic". For one "struct irq_chip_generic"
irq_ack pointer is setted, for another it is NULL.

But we have only one mask_cache per two "struct irq_chip_type".
So if we
1)unmask interrupt A for "edge type" trigger,
2)unmask interrupt B for "level type" trigger,
3)unmask interrupt C for "edge type",

we, because of usage of generic irq_gc_mask_clr_bit/irq_gc_mask_set_bit,
have hardware configured to trigger interrupt B on "edge type",
because of shared mask_cache. But kernel think that B is "level type",
so when interrupt B occur via "edge" reason, we don't ack it,
and B triggered again and again.

Signed-off-by: default avatarEvgeniy A. Dushistov <dushistov@mail.ru>
Link: https://lkml.kernel.org/r/20140726155659.GA22977@fifteen


Signed-off-by: default avatarJason Cooper <jason@lakedaemon.net>
parent 5129ee22

arch/arm/plat-orion/gpio.c

+32 −4
Original line number Diff line number Diff line
@@ -497,6 +497,34 @@ static void orion_gpio_dbg_show(struct seq_file *s, struct gpio_chip *chip) 
#define orion_gpio_dbg_show NULL

#endif



static void orion_gpio_unmask_irq(struct irq_data *d)

{

	struct irq_chip_generic *gc = irq_data_get_irq_chip_data(d);

	struct irq_chip_type *ct = irq_data_get_chip_type(d);

	u32 reg_val;

	u32 mask = d->mask;



	irq_gc_lock(gc);

	reg_val = irq_reg_readl(gc->reg_base + ct->regs.mask);

	reg_val |= mask;

	irq_reg_writel(reg_val, gc->reg_base + ct->regs.mask);

	irq_gc_unlock(gc);

}



static void orion_gpio_mask_irq(struct irq_data *d)

{

	struct irq_chip_generic *gc = irq_data_get_irq_chip_data(d);

	struct irq_chip_type *ct = irq_data_get_chip_type(d);

	u32 mask = d->mask;

	u32 reg_val;



	irq_gc_lock(gc);

	reg_val = irq_reg_readl(gc->reg_base + ct->regs.mask);

	reg_val &= ~mask;

	irq_reg_writel(reg_val, gc->reg_base + ct->regs.mask);

	irq_gc_unlock(gc);

}



void __init orion_gpio_init(struct device_node *np,

			    int gpio_base, int ngpio,

			    void __iomem *base, int mask_offset,
@@ -565,8 +593,8 @@ void __init orion_gpio_init(struct device_node *np, 
	ct = gc->chip_types;

	ct->regs.mask = ochip->mask_offset + GPIO_LEVEL_MASK_OFF;

	ct->type = IRQ_TYPE_LEVEL_HIGH | IRQ_TYPE_LEVEL_LOW;

	ct->chip.irq_mask = irq_gc_mask_clr_bit;

	ct->chip.irq_unmask = irq_gc_mask_set_bit;

	ct->chip.irq_mask = orion_gpio_mask_irq;

	ct->chip.irq_unmask = orion_gpio_unmask_irq;

	ct->chip.irq_set_type = gpio_irq_set_type;

	ct->chip.name = ochip->chip.label;
@@ -575,8 +603,8 @@ void __init orion_gpio_init(struct device_node *np, 
	ct->regs.ack = GPIO_EDGE_CAUSE_OFF;

	ct->type = IRQ_TYPE_EDGE_RISING | IRQ_TYPE_EDGE_FALLING;

	ct->chip.irq_ack = irq_gc_ack_clr_bit;

	ct->chip.irq_mask = irq_gc_mask_clr_bit;

	ct->chip.irq_unmask = irq_gc_mask_set_bit;

	ct->chip.irq_mask = orion_gpio_mask_irq;

	ct->chip.irq_unmask = orion_gpio_unmask_irq;

	ct->chip.irq_set_type = gpio_irq_set_type;

	ct->handler = handle_edge_irq;

	ct->chip.name = ochip->chip.label;