[PATCH 3.12 011/182] ARM: OMAP2+: INTC: Acknowledge stuck active interrupts

Jiri Slaby
2014-05-13T10:40:31Z

From: Stefan Sørensen <stefan.sorensen@spectralink.com>

3.12-stable review patch. If anyone has any objections, please let me know.

===============

commit 698b48532539484b012fb7c4176b959d32a17d00 upstream.

When an interrupt has become active on the INTC it will stay active
until it is acked, even if masked or de-asserted. The
INTC_PENDING_IRQn registers are however updated and since these are
used by omap_intc_handle_irq to determine which interrupt to handle,
it will never see the active interrupt. This will result in a storm of
useless interrupts that is only stopped when another higher priority
interrupt is asserted.

Fix by sending the INTC an acknowledge if we find no interrupts to
handle.

Signed-off-by: Stefan Sørensen <stefan.sorensen@spectralink.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
arch/arm/mach-omap2/irq.c | 8 ++++++++
1 file changed, 8 insertions(+)

diff --git a/arch/arm/mach-omap2/irq.c b/arch/arm/mach-omap2/irq.c
index e022a869bff2..6037a9a01ed5 100644
--- a/arch/arm/mach-omap2/irq.c
+++ b/arch/arm/mach-omap2/irq.c
@@ -222,6 +222,7 @@ void __init ti81xx_init_irq(void)
static inline void omap_intc_handle_irq(void __iomem *base_addr, struct pt_regs *regs)
{
u32 irqnr;
+ int handled_irq = 0;

do {
irqnr = readl_relaxed(base_addr + 0x98);
@@ -249,8 +250,15 @@ out:
if (irqnr) {
irqnr = irq_find_mapping(domain, irqnr);
handle_IRQ(irqnr, regs);
+ handled_irq = 1;
}
} while (irqnr);
+
+ /* If an irq is masked or deasserted while active, we will
+ * keep ending up here with no irq handled. So remove it from
+ * the INTC with an ack.*/
+ if (!handled_irq)
+ omap_ack_irq(NULL);
}

asmlinkage void __exception_irq_entry omap2_intc_handle_irq(struct pt_regs *regs)
--
1.9.3