From: Andy Gospodarek <gospo@redhat.com>
Date: Fri, 20 Feb 2009 17:29:39 -0500
Subject: [net] enic: return notify intr credits
Message-id: 20090220223036.GR12660@gospo.rdu.redhat.com
O-Subject: [RHEL5.3.z PATCH] enic: return notify intr credits
Bugzilla: 472474
RH-Acked-by: David Miller <davem@redhat.com>
RH-Acked-by: Michal Schmidt <mschmidt@redhat.com>
RH-Acked-by: Ivan Vecera <ivecera@redhat.com>

This patch was suggested to us by the hardware vendor to work around
issues using legacy mode interrupts.  Without this, the NIC doesn't work
well under Xen.  This patch was recently posted upstream and included in
Dave's net-next-2.6 tree:

    commit ed8af6b288c0643dfe0ad91f1bfc8c56c0d307cc
    Author: Scott Feldman <scofeldm@cisco.com>
    Date:   Mon Feb 9 23:23:50 2009 -0800

        enic: bug fix: return notify intr credits

        Return notify intr credits after notify intr from firmware.  This is
        especially important for legacy PCI intr mode, where not returning
        credits would cause PBA to remain asserted which would get us right
        back into the ISR.

This will resolve partially resolve RHBZ 472474.

---
 drivers/net/enic/enic.h      |    2 +-
 drivers/net/enic/enic_main.c |   17 +++++++++++------
 drivers/net/enic/vnic_intr.h |   14 ++++++++++++++
 3 files changed, 26 insertions(+), 7 deletions(-)

diff --git a/drivers/net/enic/enic.h b/drivers/net/enic/enic.h
index df8b131..23c3c56 100644
--- a/drivers/net/enic/enic.h
+++ b/drivers/net/enic/enic.h
@@ -34,7 +34,7 @@
 
 #define DRV_NAME		"enic"
 #define DRV_DESCRIPTION		"Cisco 10G Ethernet Driver"
-#define DRV_VERSION		"1.0.0.648"
+#define DRV_VERSION		"1.0.0.648-1"
 #define DRV_COPYRIGHT		"Copyright 2008 Cisco Systems, Inc"
 #define PFX			DRV_NAME ": "
 
diff --git a/drivers/net/enic/enic_main.c b/drivers/net/enic/enic_main.c
index e458cfa..25f39df 100644
--- a/drivers/net/enic/enic_main.c
+++ b/drivers/net/enic/enic_main.c
@@ -397,10 +397,13 @@ static irqreturn_t enic_isr_legacy(int irq, void *data, struct pt_regs *regs)
 		return IRQ_NONE;	/* not our interrupt */
 	}
 
-	if (ENIC_TEST_INTR(pba, ENIC_INTX_NOTIFY))
+	if (ENIC_TEST_INTR(pba, ENIC_INTX_NOTIFY)) {
+		vnic_intr_return_all_credits(&enic->intr[ENIC_INTX_NOTIFY]);
 		enic_notify_check(enic);
+	}
 
 	if (ENIC_TEST_INTR(pba, ENIC_INTX_ERR)) {
+		vnic_intr_return_all_credits(&enic->intr[ENIC_INTX_ERR]);
 		enic_log_q_error(enic);
 		/* schedule recovery from WQ/RQ error */
 		schedule_work(&enic->reset);
@@ -473,6 +476,8 @@ static irqreturn_t enic_isr_msix_err(int irq, void *data, struct pt_regs *regs)
 {
 	struct enic *enic = data;
 
+	vnic_intr_return_all_credits(&enic->intr[ENIC_MSIX_ERR]);
+
 	enic_log_q_error(enic);
 
 	/* schedule recovery from WQ/RQ error */
@@ -485,8 +490,8 @@ static irqreturn_t enic_isr_msix_notify(int irq, void *data, struct pt_regs *reg
 {
 	struct enic *enic = data;
 
+	vnic_intr_return_all_credits(&enic->intr[ENIC_MSIX_NOTIFY]);
 	enic_notify_check(enic);
-	vnic_intr_unmask(&enic->intr[ENIC_MSIX_NOTIFY]);
 
 	return IRQ_HANDLED;
 }
@@ -613,7 +618,7 @@ static inline void enic_queue_wq_skb(struct enic *enic,
 			vlan_tag_insert, vlan_tag);
 }
 
-/* netif_tx_lock held, process context with BHs disabled */
+/* netif_tx_lock held, process context with BHs disabled, or BH */
 static int enic_hard_start_xmit(struct sk_buff *skb, struct net_device *netdev)
 {
 	struct enic *enic = netdev_priv(netdev);
@@ -1065,7 +1070,7 @@ static int enic_poll(struct net_device *netdev, int *budget)
 			lro_flush_all(&enic->lro_mgr);
 
 		netif_rx_complete(netdev);
-		vnic_intr_unmask(&enic->intr[ENIC_MSIX_RQ]);
+		vnic_intr_unmask(&enic->intr[ENIC_INTX_WQ_RQ]);
 		return 0;
 	}
 
@@ -1091,9 +1096,9 @@ static int enic_poll_msix(struct net_device *netdev, int *budget)
 
 		vnic_rq_fill(&enic->rq[0], enic_rq_alloc_buf);
 
-		/* Accumulate intr event credits for this polling
+		/* Return intr event credits for this polling
 		 * cycle.  An intr event is the completion of a
-		 * a WQ or RQ packet.
+		 * RQ packet.
 		 */
 
 		vnic_intr_return_credits(&enic->intr[ENIC_MSIX_RQ],
diff --git a/drivers/net/enic/vnic_intr.h b/drivers/net/enic/vnic_intr.h
index ce633a5..9a53604 100644
--- a/drivers/net/enic/vnic_intr.h
+++ b/drivers/net/enic/vnic_intr.h
@@ -76,6 +76,20 @@ static inline void vnic_intr_return_credits(struct vnic_intr *intr,
 	iowrite32(int_credit_return, &intr->ctrl->int_credit_return);
 }
 
+static inline unsigned int vnic_intr_credits(struct vnic_intr *intr)
+{
+	return ioread32(&intr->ctrl->int_credits);
+}
+
+static inline void vnic_intr_return_all_credits(struct vnic_intr *intr)
+{
+	unsigned int credits = vnic_intr_credits(intr);
+	int unmask = 1;
+	int reset_timer = 1;
+
+	vnic_intr_return_credits(intr, credits, unmask, reset_timer);
+}
+
 static inline u32 vnic_intr_legacy_pba(u32 __iomem *legacy_pba)
 {
 	/* read PBA without clearing */
-- 
1.5.2.1