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Commit c04cb347 authored by Michael Chan's avatar Michael Chan Committed by David S. Miller
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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: default avatarMichael Chan <mchan@broadcom.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 8ed5d97e

drivers/net/tg3.c

+10 −2
Original line number Diff line number Diff line
@@ -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)) {