netdev - Re: [PATCH 15/22] e1000: simplify msi specific interrupt handler

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Date:	Mon, 11 Dec 2006 09:48:20 -0500
From:	Jeff Garzik <jgarzik@...ox.com>
To:	"Kok, Auke" <auke-jan.h.kok@...el.com>
CC:	netdev@...r.kernel.org,
	"Brandeburg, Jesse" <jesse.brandeburg@...el.com>,
	"Kok, Auke" <auke@...-projects.org>,
	"Ronciak, John" <john.ronciak@...el.com>
Subject: Re: [PATCH 15/22] e1000: simplify msi specific interrupt handler

Kok, Auke wrote:
> Simplify the msi interrupt handler to avoid issues with delayed ICR reads.
> This avoids adapter specific problems at the cost of some performance.
> 
> Signed-off-by: Jesse Brandeburg <jesse.brandeburg@...el.com>
> Signed-off-by: Auke Kok <auke-jan.h.kok@...el.com>
> ---
> 
>  drivers/net/e1000/e1000.h      |    1 -
>  drivers/net/e1000/e1000_main.c |   60 +++++++++++++---------------------------
>  2 files changed, 19 insertions(+), 42 deletions(-)
> 
> diff --git a/drivers/net/e1000/e1000.h b/drivers/net/e1000/e1000.h
> index f091042..8e7acb0 100644
> --- a/drivers/net/e1000/e1000.h
> +++ b/drivers/net/e1000/e1000.h
> @@ -257,7 +257,6 @@ struct e1000_adapter {
>  	spinlock_t tx_queue_lock;
>  #endif
>  	atomic_t irq_sem;
> -	unsigned int detect_link;
>  	unsigned int total_tx_bytes;
>  	unsigned int total_tx_packets;
>  	unsigned int total_rx_bytes;
> diff --git a/drivers/net/e1000/e1000_main.c b/drivers/net/e1000/e1000_main.c
> index 67fc379..cb6b732 100644
> --- a/drivers/net/e1000/e1000_main.c
> +++ b/drivers/net/e1000/e1000_main.c
> @@ -3778,8 +3778,8 @@ e1000_update_stats(struct e1000_adapter 
>   * @data: pointer to a network interface device structure
>   **/
>  
> -static
> -irqreturn_t e1000_intr_msi(int irq, void *data)
> +static irqreturn_t
> +e1000_intr_msi(int irq, void *data)
>  {
>  	struct net_device *netdev = data;
>  	struct e1000_adapter *adapter = netdev_priv(netdev);
> @@ -3787,49 +3787,27 @@ irqreturn_t e1000_intr_msi(int irq, void
>  #ifndef CONFIG_E1000_NAPI
>  	int i;
>  #endif
> +	uint32_t icr = E1000_READ_REG(hw, ICR);
>  
> -	/* this code avoids the read of ICR but has to get 1000 interrupts
> -	 * at every link change event before it will notice the change */
> -	if (++adapter->detect_link >= 1000) {
> -		uint32_t icr = E1000_READ_REG(hw, ICR);
>  #ifdef CONFIG_E1000_NAPI
> -		/* read ICR disables interrupts using IAM, so keep up with our
> -		 * enable/disable accounting */
> -		atomic_inc(&adapter->irq_sem);
> +	/* read ICR disables interrupts using IAM, so keep up with our
> +	 * enable/disable accounting */
> +	atomic_inc(&adapter->irq_sem);
>  #endif
> -		adapter->detect_link = 0;
> -		if ((icr & (E1000_ICR_RXSEQ | E1000_ICR_LSC)) &&
> -		    (icr & E1000_ICR_INT_ASSERTED)) {
> -			hw->get_link_status = 1;
> -			/* 80003ES2LAN workaround--
> -			* For packet buffer work-around on link down event;
> -			* disable receives here in the ISR and
> -			* reset adapter in watchdog
> -			*/
> -			if (netif_carrier_ok(netdev) &&
> -			    (adapter->hw.mac_type == e1000_80003es2lan)) {
> -				/* disable receives */
> -				uint32_t rctl = E1000_READ_REG(hw, RCTL);
> -				E1000_WRITE_REG(hw, RCTL, rctl & ~E1000_RCTL_EN);
> -			}
> -			/* guard against interrupt when we're going down */
> -			if (!test_bit(__E1000_DOWN, &adapter->flags))
> -				mod_timer(&adapter->watchdog_timer,
> -				          jiffies + 1);
> +	if (icr & (E1000_ICR_RXSEQ | E1000_ICR_LSC)) {
> +		hw->get_link_status = 1;
> +		/* 80003ES2LAN workaround-- For packet buffer work-around on
> +		 * link down event; disable receives here in the ISR and reset
> +		 * adapter in watchdog */
> +		if (netif_carrier_ok(netdev) &&
> +		    (adapter->hw.mac_type == e1000_80003es2lan)) {
> +			/* disable receives */
> +			uint32_t rctl = E1000_READ_REG(hw, RCTL);
> +			E1000_WRITE_REG(hw, RCTL, rctl & ~E1000_RCTL_EN);

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