Re: [PATCH 03/24] MIPS: Provide a generic plat_irq_dispatch

From: Qais Yousef
Date: Wed Sep 17 2014 - 04:56:36 EST


Hi Andrew,

On 09/16/2014 12:51 AM, Andrew Bresticker wrote:
For platforms which boot with device-tree or have correctly chained
all external interrupt controllers, a generic plat_irq_dispatch() can
be used. Implement a plat_irq_dispatch() which simply handles all the
pending interrupts as reported by C0_Cause.

Signed-off-by: Andrew Bresticker <abrestic@xxxxxxxxxxxx>
---
arch/mips/kernel/irq_cpu.c | 15 +++++++++++++++
1 file changed, 15 insertions(+)

diff --git a/arch/mips/kernel/irq_cpu.c b/arch/mips/kernel/irq_cpu.c
index ca98a9f..f17bd08 100644
--- a/arch/mips/kernel/irq_cpu.c
+++ b/arch/mips/kernel/irq_cpu.c
@@ -94,6 +94,21 @@ static struct irq_chip mips_mt_cpu_irq_controller = {
.irq_eoi = unmask_mips_irq,
};
+asmlinkage void __weak plat_irq_dispatch(void)
+{
+ unsigned long pending = read_c0_cause() & read_c0_status() & ST0_IM;
+ int irq;
+
+ if (!pending) {
+ spurious_interrupt();
+ return;
+ }
+
+ pending >>= CAUSEB_IP;
+ for_each_set_bit(irq, &pending, 8)
+ do_IRQ(MIPS_CPU_IRQ_BASE + irq);
+}
+

If I read the for_each_set_bit() macro correctly it'll iterate through the bits from least to most significant ones which is the reversed priority expected. Some platforms set timer interrupt to bit 7 which is should be the highest priority interrupt. Also when cpu_has_vint is set the hardware prioritirise from most significant to least significant bits so if plat_irq_dispatch() is used with set_vi_handler() it'll cause interrupts to be serviced in the wrong order.

Qais

static int mips_cpu_intc_map(struct irq_domain *d, unsigned int irq,
irq_hw_number_t hw)
{

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