i40e/i40evf: Add support for writeback on ITR feature for X722

X722 fixes an issue from X710 where TX descriptor WB would not happen if
the interrupts were disabled. In order for the write backs to happen a
bit needs to be set in the dynamic interrupt control register called
WB_ON_ITR. With this feature, the SW driver need not arm SW interrupts to
work around the issue in X710.

Signed-off-by: Anjali Singhai Jain <anjali.singhai@intel.com>
Signed-off-by: Catherine Sullivan <catherine.sullivan@intel.com>
Tested-by: Jim Young <james.m.young@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

7 files changed, 74 insertions, 18 deletions

diff --git a/drivers/net/ethernet/intel/i40e/i40e.h b/drivers/net/ethernet/intel/i40e/i40e.h
index 66d0780f1297..0f97883c1493 100644
--- a/drivers/net/ethernet/intel/i40e/i40e.h
+++ b/drivers/net/ethernet/intel/i40e/i40e.h
@@ -560,6 +560,7 @@ struct i40e_q_vector {
 	cpumask_t affinity_mask;
 	struct rcu_head rcu;	/* to avoid race with update stats on free */
 	char name[I40E_INT_NAME_STR_LEN];
+	bool arm_wb_state;
 } ____cacheline_internodealigned_in_smp;
 
 /* lan device */
diff --git a/drivers/net/ethernet/intel/i40e/i40e_main.c b/drivers/net/ethernet/intel/i40e/i40e_main.c
index 2e8416560632..28f547ce4eb5 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_main.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_main.c
@@ -7071,6 +7071,8 @@ static int i40e_alloc_rings(struct i40e_vsi *vsi)
 		tx_ring->count = vsi->num_desc;
 		tx_ring->size = 0;
 		tx_ring->dcb_tc = 0;
+		if (vsi->back->flags & I40E_FLAG_WB_ON_ITR_CAPABLE)
+			tx_ring->flags = I40E_TXR_FLAGS_WB_ON_ITR;
 		vsi->tx_rings[i] = tx_ring;
 
 		rx_ring = &tx_ring[1];
diff --git a/drivers/net/ethernet/intel/i40e/i40e_txrx.c b/drivers/net/ethernet/intel/i40e/i40e_txrx.c
index 330e4ef43cd8..7d0a5ea08656 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_txrx.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_txrx.c
@@ -853,15 +853,40 @@ static bool i40e_clean_tx_irq(struct i40e_ring *tx_ring, int budget)
  **/
 static void i40e_force_wb(struct i40e_vsi *vsi, struct i40e_q_vector *q_vector)
 {
-	u32 val = I40E_PFINT_DYN_CTLN_INTENA_MASK |
-		  I40E_PFINT_DYN_CTLN_ITR_INDX_MASK | /* set noitr */
-		  I40E_PFINT_DYN_CTLN_SWINT_TRIG_MASK |
-		  I40E_PFINT_DYN_CTLN_SW_ITR_INDX_ENA_MASK;
-		  /* allow 00 to be written to the index */
-
-	wr32(&vsi->back->hw,
-	     I40E_PFINT_DYN_CTLN(q_vector->v_idx + vsi->base_vector - 1),
-	     val);
+	u16 flags = q_vector->tx.ring[0].flags;
+
+	if (flags & I40E_TXR_FLAGS_WB_ON_ITR) {
+		u32 val;
+
+		if (q_vector->arm_wb_state)
+			return;
+
+		val = I40E_PFINT_DYN_CTLN_WB_ON_ITR_MASK;
+
+		wr32(&vsi->back->hw,
+		     I40E_PFINT_DYN_CTLN(q_vector->v_idx +
+					 vsi->base_vector - 1),
+		     val);
+		q_vector->arm_wb_state = true;
+	} else if (vsi->back->flags & I40E_FLAG_MSIX_ENABLED) {
+		u32 val = I40E_PFINT_DYN_CTLN_INTENA_MASK |
+			  I40E_PFINT_DYN_CTLN_ITR_INDX_MASK | /* set noitr */
+			  I40E_PFINT_DYN_CTLN_SWINT_TRIG_MASK |
+			  I40E_PFINT_DYN_CTLN_SW_ITR_INDX_ENA_MASK;
+			  /* allow 00 to be written to the index */
+
+		wr32(&vsi->back->hw,
+		     I40E_PFINT_DYN_CTLN(q_vector->v_idx +
+					 vsi->base_vector - 1), val);
+	} else {
+		u32 val = I40E_PFINT_DYN_CTL0_INTENA_MASK |
+			  I40E_PFINT_DYN_CTL0_ITR_INDX_MASK | /* set noitr */
+			  I40E_PFINT_DYN_CTL0_SWINT_TRIG_MASK |
+			  I40E_PFINT_DYN_CTL0_SW_ITR_INDX_ENA_MASK;
+			/* allow 00 to be written to the index */
+
+		wr32(&vsi->back->hw, I40E_PFINT_DYN_CTL0, val);
+	}
 }
 
 /**
@@ -1918,6 +1943,9 @@ int i40e_napi_poll(struct napi_struct *napi, int budget)
 		return budget;
 	}
 
+	if (vsi->back->flags & I40E_TXR_FLAGS_WB_ON_ITR)
+		q_vector->arm_wb_state = false;
+
 	/* Work is done so exit the polling mode and re-enable the interrupt */
 	napi_complete(napi);
 	if (vsi->back->flags & I40E_FLAG_MSIX_ENABLED) {
diff --git a/drivers/net/ethernet/intel/i40e/i40e_txrx.h b/drivers/net/ethernet/intel/i40e/i40e_txrx.h
index 8b618d0151cd..0e40994500c1 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_txrx.h
+++ b/drivers/net/ethernet/intel/i40e/i40e_txrx.h
@@ -265,6 +265,8 @@ struct i40e_ring {
 	bool ring_active;		/* is ring online or not */
 	bool arm_wb;		/* do something to arm write back */
 
+	u16 flags;
+#define I40E_TXR_FLAGS_WB_ON_ITR	BIT(0)
 	/* stats structs */
 	struct i40e_queue_stats	stats;
 	struct u64_stats_sync syncp;
diff --git a/drivers/net/ethernet/intel/i40evf/i40e_txrx.c b/drivers/net/ethernet/intel/i40evf/i40e_txrx.c
index 60f88e4ad065..6dbcbca77279 100644
--- a/drivers/net/ethernet/intel/i40evf/i40e_txrx.c
+++ b/drivers/net/ethernet/intel/i40evf/i40e_txrx.c
@@ -366,15 +366,32 @@ static bool i40e_clean_tx_irq(struct i40e_ring *tx_ring, int budget)
  **/
 static void i40e_force_wb(struct i40e_vsi *vsi, struct i40e_q_vector *q_vector)
 {
-	u32 val = I40E_VFINT_DYN_CTLN_INTENA_MASK |
-		  I40E_VFINT_DYN_CTLN1_ITR_INDX_MASK | /* set noitr */
-		  I40E_VFINT_DYN_CTLN_SWINT_TRIG_MASK |
-		  I40E_VFINT_DYN_CTLN_SW_ITR_INDX_ENA_MASK;
-		  /* allow 00 to be written to the index */
-
-	wr32(&vsi->back->hw,
-	     I40E_VFINT_DYN_CTLN1(q_vector->v_idx + vsi->base_vector - 1),
-	     val);
+	u16 flags = q_vector->tx.ring[0].flags;
+
+	if (flags & I40E_TXR_FLAGS_WB_ON_ITR) {
+		u32 val;
+
+		if (q_vector->arm_wb_state)
+			return;
+
+		val = I40E_VFINT_DYN_CTLN1_WB_ON_ITR_MASK;
+
+		wr32(&vsi->back->hw,
+		     I40E_VFINT_DYN_CTLN1(q_vector->v_idx +
+					  vsi->base_vector - 1),
+		     val);
+		q_vector->arm_wb_state = true;
+	} else {
+		u32 val = I40E_VFINT_DYN_CTLN1_INTENA_MASK |
+			  I40E_VFINT_DYN_CTLN1_ITR_INDX_MASK | /* set noitr */
+			  I40E_VFINT_DYN_CTLN1_SWINT_TRIG_MASK |
+			  I40E_VFINT_DYN_CTLN1_SW_ITR_INDX_ENA_MASK;
+			  /* allow 00 to be written to the index */
+
+		wr32(&vsi->back->hw,
+		     I40E_VFINT_DYN_CTLN1(q_vector->v_idx +
+					  vsi->base_vector - 1), val);
+	}
 }
 
 /**
@@ -1372,6 +1389,9 @@ int i40evf_napi_poll(struct napi_struct *napi, int budget)
 		return budget;
 	}
 
+	if (vsi->back->flags & I40E_TXR_FLAGS_WB_ON_ITR)
+		q_vector->arm_wb_state = false;
+
 	/* Work is done so exit the polling mode and re-enable the interrupt */
 	napi_complete(napi);
 	i40e_update_enable_itr(vsi, q_vector);
diff --git a/drivers/net/ethernet/intel/i40evf/i40e_txrx.h b/drivers/net/ethernet/intel/i40evf/i40e_txrx.h
index b2f9b8203c67..17bb59d3016c 100644
--- a/drivers/net/ethernet/intel/i40evf/i40e_txrx.h
+++ b/drivers/net/ethernet/intel/i40evf/i40e_txrx.h
@@ -262,6 +262,8 @@ struct i40e_ring {
 	bool ring_active;		/* is ring online or not */
 	bool arm_wb;		/* do something to arm write back */
 
+	u16 flags;
+#define I40E_TXR_FLAGS_WB_ON_ITR	BIT(0)
 	/* stats structs */
 	struct i40e_queue_stats	stats;
 	struct u64_stats_sync syncp;
diff --git a/drivers/net/ethernet/intel/i40evf/i40evf.h b/drivers/net/ethernet/intel/i40evf/i40evf.h
index fa421d6020be..3817cbbf45e6 100644
--- a/drivers/net/ethernet/intel/i40evf/i40evf.h
+++ b/drivers/net/ethernet/intel/i40evf/i40evf.h
@@ -117,6 +117,7 @@ struct i40e_q_vector {
 	u8 num_ringpairs;	/* total number of ring pairs in vector */
 	int v_idx;	  /* vector index in list */
 	char name[IFNAMSIZ + 9];
+	bool arm_wb_state;
 	cpumask_var_t affinity_mask;
 };