Commit b8a7ce7b authored by Michael Chan's avatar Michael Chan Committed by David S. Miller
Browse files

[BNX2]: Reduce spurious INTA 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.

Add read back to flush the I/O write to deassert the IRQ immediately.
We also store the last_status_idx immediately in the IRQ handler to
help detect whether the interrupt is ours or not when the IRQ is
entered again before ->poll gets called.

Signed-off-by: default avatarMichael Chan <mchan@broadcom.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 9b1084b8

drivers/net/bnx2.c

+11 −2
Original line number Diff line number Diff line
@@ -2547,6 +2547,7 @@ bnx2_interrupt(int irq, void *dev_instance) 
{

	struct net_device *dev = dev_instance;

	struct bnx2 *bp = netdev_priv(dev);

	struct status_block *sblk = bp->status_blk;



	/* When using INTx, it is possible for the interrupt to arrive

	 * at the CPU before the status block posted prior to the
@@ -2554,7 +2555,7 @@ bnx2_interrupt(int irq, void *dev_instance) 
	 * When using MSI, the MSI message will always complete after

	 * the status block write.

	 */

	if ((bp->status_blk->status_idx == bp->last_status_idx) &&

	if ((sblk->status_idx == bp->last_status_idx) &&

	    (REG_RD(bp, BNX2_PCICFG_MISC_STATUS) &

	     BNX2_PCICFG_MISC_STATUS_INTA_VALUE))

		return IRQ_NONE;
@@ -2563,11 +2564,19 @@ bnx2_interrupt(int irq, void *dev_instance) 
		BNX2_PCICFG_INT_ACK_CMD_USE_INT_HC_PARAM |

		BNX2_PCICFG_INT_ACK_CMD_MASK_INT);



	/* Read back to deassert IRQ immediately to avoid too many

	 * spurious interrupts.

	 */

	REG_RD(bp, BNX2_PCICFG_INT_ACK_CMD);



	/* Return here if interrupt is shared and is disabled. */

	if (unlikely(atomic_read(&bp->intr_sem) != 0))

		return IRQ_HANDLED;



	netif_rx_schedule(dev);

	if (netif_rx_schedule_prep(dev)) {

		bp->last_status_idx = sblk->status_idx;

		__netif_rx_schedule(dev);

	}



	return IRQ_HANDLED;

}

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