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[TG3]: Eliminate spurious interrupts. 

Spurious interrupts are often encountered especially on systems
using the 8259 PIC mode.  This is because the I/O write to deassert
the interrupt is posted and won't get to the chip immediately.  As
a result, the IRQ may remain asserted after the IRQ handler exits,
causing spurious interrupts.

Flush the interrupt mailbox in non-MSI handlers to de-assert the
IRQ immediately.  This seems to be the most straight forward approach
after discussion with Jeff Garzik and David Miller.

Signed-off-by: Michael Chan <mchan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Michael Chan 2007-05-07 00:26:15 -07:00 committed by David S. Miller
parent 8ed5d97e5e
commit c04cb34725
1 changed files with 10 additions and 2 deletions
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12
drivers/net/tg3.c
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@ -3590,8 +3590,12 @@ static irqreturn_t tg3_interrupt(int irq, void *dev_id)
* Writing non-zero to intr-mbox-0 additional tells the
* NIC to stop sending us irqs, engaging "in-intr-handler"
* event coalescing.
*
* Flush the mailbox to de-assert the IRQ immediately to prevent
* spurious interrupts. The flush impacts performance but
* excessive spurious interrupts can be worse in some cases.
*/
tw32_mailbox(MAILBOX_INTERRUPT_0 + TG3_64BIT_REG_LOW, 0x00000001);
tw32_mailbox_f(MAILBOX_INTERRUPT_0 + TG3_64BIT_REG_LOW, 0x00000001);
if (tg3_irq_sync(tp))
goto out;
sblk->status &= ~SD_STATUS_UPDATED;
@ -3635,8 +3639,12 @@ static irqreturn_t tg3_interrupt_tagged(int irq, void *dev_id)
* writing non-zero to intr-mbox-0 additional tells the
* NIC to stop sending us irqs, engaging "in-intr-handler"
* event coalescing.
*
* Flush the mailbox to de-assert the IRQ immediately to prevent
* spurious interrupts. The flush impacts performance but
* excessive spurious interrupts can be worse in some cases.
*/
tw32_mailbox(MAILBOX_INTERRUPT_0 + TG3_64BIT_REG_LOW, 0x00000001);
tw32_mailbox_f(MAILBOX_INTERRUPT_0 + TG3_64BIT_REG_LOW, 0x00000001);
if (tg3_irq_sync(tp))
goto out;
if (netif_rx_schedule_prep(dev)) {