[loongson-PATCH-v3 21/25] flush posted write to irq

[wuzhangjin@gmail.com]

From: Wu Zhangjin <wuzj@lemote.com>

read back to flush the posted write, otherwise, there will be many
spurious irqs.

the previous talk: http://www.spinics.net/lists/mips/msg33749.html

Reviewed-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Signed-off-by: Yan Hua <yanh@lemote.com>
---
 arch/mips/kernel/i8259.c               |    2 ++
 arch/mips/loongson/common/bonito-irq.c |    4 ++++
 2 files changed, 6 insertions(+), 0 deletions(-)

diff --git a/arch/mips/kernel/i8259.c b/arch/mips/kernel/i8259.c
index 01c0885..b0254c6 100644
--- a/arch/mips/kernel/i8259.c
+++ b/arch/mips/kernel/i8259.c
@@ -177,10 +177,12 @@ handle_real_irq:
                outb(cached_slave_mask, PIC_SLAVE_IMR);
                outb(0x60+(irq&7), PIC_SLAVE_CMD);/* 'Specific EOI' to slave */
                outb(0x60+PIC_CASCADE_IR, PIC_MASTER_CMD); /* 'Specific EOI' to 
master-IRQ2 */
+               inb(PIC_MASTER_CMD);    /* flush posted write */
        } else {
                inb(PIC_MASTER_IMR);    /* DUMMY - (do we need this?) */
                outb(cached_master_mask, PIC_MASTER_IMR);
                outb(0x60+irq, PIC_MASTER_CMD); /* 'Specific EOI to master */
+               inb(PIC_MASTER_CMD);    /* flush posted write */
        }
        smtc_im_ack_irq(irq);
        spin_unlock_irqrestore(&i8259A_lock, flags);
diff --git a/arch/mips/loongson/common/bonito-irq.c 
b/arch/mips/loongson/common/bonito-irq.c
index 940c1f0..8f5a455 100644
--- a/arch/mips/loongson/common/bonito-irq.c
+++ b/arch/mips/loongson/common/bonito-irq.c
@@ -36,12 +36,16 @@
 static inline void bonito_irq_enable(unsigned int irq)
 {
        LOONGSON_INTENSET = (1 << (irq - LOONGSON_IRQ_BASE));
+       /* flush posted write */
+       (void)LOONGSON_INTENSET;
        mmiowb();
 }
 
 static inline void bonito_irq_disable(unsigned int irq)
 {
        LOONGSON_INTENCLR = (1 << (irq - LOONGSON_IRQ_BASE));
+       /* flush posted write */
+       (void)LOONGSON_INTENCLR;
        mmiowb();
 }
 
-- 
1.6.0.4