ionic: missed doorbell workaround

In one version of the HW there is a remote possibility that it
will miss the doorbell ring. This adds a bit of protection to
be sure we don't stall a queue from a missed doorbell.

Fixes: 0f3154e6bcb3 ("ionic: Add Tx and Rx handling")
Signed-off-by: Allen Hubbe <[e-mail]>
Signed-off-by: Shannon Nelson <[e-mail]>
Signed-off-by: Jakub Kicinski <[e-mail]>

drivers/net/ethernet/pensando/ionic/ionic_dev.c

···
 		q->lif->index, q->name, q->hw_type, q->hw_index,
 		q->head_idx, ring_doorbell);
 
-	if (ring_doorbell)
+	if (ring_doorbell) {
 		ionic_dbell_ring(lif->kern_dbpage, q->hw_type,
 				 q->dbval | q->head_idx);
+
+		q->dbell_jiffies = jiffies;
+
+		if (q_to_qcq(q)->napi_qcq)
+			mod_timer(&q_to_qcq(q)->napi_qcq->napi_deadline,
+				  jiffies + IONIC_NAPI_DEADLINE);
+	}
 }
 
 static bool ionic_q_is_posted(struct ionic_queue *q, unsigned int pos)

drivers/net/ethernet/pensando/ionic/ionic_dev.h

···
 #define IONIC_DEV_INFO_REG_COUNT	32
 #define IONIC_DEV_CMD_REG_COUNT		32
 
+#define IONIC_NAPI_DEADLINE		(HZ / 200)	/* 5ms */
+#define IONIC_ADMIN_DOORBELL_DEADLINE	(HZ / 2)	/* 500ms */
+#define IONIC_TX_DOORBELL_DEADLINE	(HZ / 100)	/* 10ms */
+#define IONIC_RX_MIN_DOORBELL_DEADLINE	(HZ / 100)	/* 10ms */
+#define IONIC_RX_MAX_DOORBELL_DEADLINE	(HZ * 5)	/* 5s */
+
 struct ionic_dev_bar {
 	void __iomem *vaddr;
 	phys_addr_t bus_addr;
···
 	struct ionic_lif *lif;
 	struct ionic_desc_info *info;
 	u64 dbval;
+	unsigned long dbell_deadline;
+	unsigned long dbell_jiffies;
 	u16 head_idx;
 	u16 tail_idx;
 	unsigned int index;
···
 		     unsigned int stop_index);
 int ionic_heartbeat_check(struct ionic *ionic);
 bool ionic_is_fw_running(struct ionic_dev *idev);
+
+bool ionic_adminq_poke_doorbell(struct ionic_queue *q);
+bool ionic_txq_poke_doorbell(struct ionic_queue *q);
+bool ionic_rxq_poke_doorbell(struct ionic_queue *q);
 
 #endif /* _IONIC_DEV_H_ */

drivers/net/ethernet/pensando/ionic/ionic_lif.c

···
 
 #include "ionic.h"
 #include "ionic_bus.h"
+#include "ionic_dev.h"
 #include "ionic_lif.h"
 #include "ionic_txrx.h"
 #include "ionic_ethtool.h"
···
 	}
 }
 
+static void ionic_napi_deadline(struct timer_list *timer)
+{
+	struct ionic_qcq *qcq = container_of(timer, struct ionic_qcq, napi_deadline);
+
+	napi_schedule(&qcq->napi);
+}
+
 static irqreturn_t ionic_isr(int irq, void *data)
 {
 	struct napi_struct *napi = data;
···
 		synchronize_irq(qcq->intr.vector);
 		irq_set_affinity_hint(qcq->intr.vector, NULL);
 		napi_disable(&qcq->napi);
+		del_timer_sync(&qcq->napi_deadline);
 	}
 
 	/* If there was a previous fw communcation error, don't bother with
···
 
 	n_qcq->intr.vector = src_qcq->intr.vector;
 	n_qcq->intr.index = src_qcq->intr.index;
+	n_qcq->napi_qcq = src_qcq->napi_qcq;
 }
 
 static int ionic_alloc_qcq_interrupt(struct ionic_lif *lif, struct ionic_qcq *qcq)
···
 	dev_dbg(dev, "txq->hw_type %d\n", q->hw_type);
 	dev_dbg(dev, "txq->hw_index %d\n", q->hw_index);
 
-	if (test_bit(IONIC_LIF_F_SPLIT_INTR, lif->state))
+	q->dbell_deadline = IONIC_TX_DOORBELL_DEADLINE;
+	q->dbell_jiffies = jiffies;
+
+	if (test_bit(IONIC_LIF_F_SPLIT_INTR, lif->state)) {
 		netif_napi_add(lif->netdev, &qcq->napi, ionic_tx_napi);
+		qcq->napi_qcq = qcq;
+		timer_setup(&qcq->napi_deadline, ionic_napi_deadline, 0);
+	}
 
 	qcq->flags |= IONIC_QCQ_F_INITED;
 
···
 	dev_dbg(dev, "rxq->hw_type %d\n", q->hw_type);
 	dev_dbg(dev, "rxq->hw_index %d\n", q->hw_index);
 
+	q->dbell_deadline = IONIC_RX_MIN_DOORBELL_DEADLINE;
+	q->dbell_jiffies = jiffies;
+
 	if (test_bit(IONIC_LIF_F_SPLIT_INTR, lif->state))
 		netif_napi_add(lif->netdev, &qcq->napi, ionic_rx_napi);
 	else
 		netif_napi_add(lif->netdev, &qcq->napi, ionic_txrx_napi);
+
+	qcq->napi_qcq = qcq;
+	timer_setup(&qcq->napi_deadline, ionic_napi_deadline, 0);
 
 	qcq->flags |= IONIC_QCQ_F_INITED;
 
···
 	struct ionic_dev *idev = &lif->ionic->idev;
 	unsigned long irqflags;
 	unsigned int flags = 0;
+	bool resched = false;
 	int rx_work = 0;
 	int tx_work = 0;
 	int n_work = 0;
···
 		credits = n_work + a_work + rx_work + tx_work;
 		ionic_intr_credits(idev->intr_ctrl, intr->index, credits, flags);
 	}
+
+	if (!a_work && ionic_adminq_poke_doorbell(&lif->adminqcq->q))
+		resched = true;
+	if (lif->hwstamp_rxq && !rx_work && ionic_rxq_poke_doorbell(&lif->hwstamp_rxq->q))
+		resched = true;
+	if (lif->hwstamp_txq && !tx_work && ionic_txq_poke_doorbell(&lif->hwstamp_txq->q))
+		resched = true;
+	if (resched)
+		mod_timer(&lif->adminqcq->napi_deadline,
+			  jiffies + IONIC_NAPI_DEADLINE);
 
 	return work_done;
 }
···
 	dev_dbg(dev, "adminq->hw_type %d\n", q->hw_type);
 	dev_dbg(dev, "adminq->hw_index %d\n", q->hw_index);
 
+	q->dbell_deadline = IONIC_ADMIN_DOORBELL_DEADLINE;
+	q->dbell_jiffies = jiffies;
+
 	netif_napi_add(lif->netdev, &qcq->napi, ionic_adminq_napi);
+
+	qcq->napi_qcq = qcq;
+	timer_setup(&qcq->napi_deadline, ionic_napi_deadline, 0);
 
 	napi_enable(&qcq->napi);
 

drivers/net/ethernet/pensando/ionic/ionic_lif.h

···
 	struct ionic_queue q;
 	struct ionic_cq cq;
 	struct ionic_intr_info intr;
+	struct timer_list napi_deadline;
 	struct napi_struct napi;
 	unsigned int flags;
+	struct ionic_qcq *napi_qcq;
 	struct dentry *dentry;
 };
 

drivers/net/ethernet/pensando/ionic/ionic_main.c

···
 	complete_all(&ctx->work);
 }
 
+bool ionic_adminq_poke_doorbell(struct ionic_queue *q)
+{
+	struct ionic_lif *lif = q->lif;
+	unsigned long now, then, dif;
+	unsigned long irqflags;
+
+	spin_lock_irqsave(&lif->adminq_lock, irqflags);
+
+	if (q->tail_idx == q->head_idx) {
+		spin_unlock_irqrestore(&lif->adminq_lock, irqflags);
+		return false;
+	}
+
+	now = READ_ONCE(jiffies);
+	then = q->dbell_jiffies;
+	dif = now - then;
+
+	if (dif > q->dbell_deadline) {
+		ionic_dbell_ring(q->lif->kern_dbpage, q->hw_type,
+				 q->dbval | q->head_idx);
+
+		q->dbell_jiffies = now;
+	}
+
+	spin_unlock_irqrestore(&lif->adminq_lock, irqflags);
+
+	return true;
+}
+
 int ionic_adminq_post(struct ionic_lif *lif, struct ionic_admin_ctx *ctx)
 {
 	struct ionic_desc_info *desc_info;

drivers/net/ethernet/pensando/ionic/ionic_txrx.c

···
 	ionic_q_post(q, ring_dbell, cb_func, cb_arg);
 }
 
+bool ionic_txq_poke_doorbell(struct ionic_queue *q)
+{
+	unsigned long now, then, dif;
+	struct netdev_queue *netdev_txq;
+	struct net_device *netdev;
+
+	netdev = q->lif->netdev;
+	netdev_txq = netdev_get_tx_queue(netdev, q->index);
+
+	HARD_TX_LOCK(netdev, netdev_txq, smp_processor_id());
+
+	if (q->tail_idx == q->head_idx) {
+		HARD_TX_UNLOCK(netdev, netdev_txq);
+		return false;
+	}
+
+	now = READ_ONCE(jiffies);
+	then = q->dbell_jiffies;
+	dif = now - then;
+
+	if (dif > q->dbell_deadline) {
+		ionic_dbell_ring(q->lif->kern_dbpage, q->hw_type,
+				 q->dbval | q->head_idx);
+
+		q->dbell_jiffies = now;
+	}
+
+	HARD_TX_UNLOCK(netdev, netdev_txq);
+
+	return true;
+}
+
+bool ionic_rxq_poke_doorbell(struct ionic_queue *q)
+{
+	unsigned long now, then, dif;
+
+	/* no lock, called from rx napi or txrx napi, nothing else can fill */
+
+	if (q->tail_idx == q->head_idx)
+		return false;
+
+	now = READ_ONCE(jiffies);
+	then = q->dbell_jiffies;
+	dif = now - then;
+
+	if (dif > q->dbell_deadline) {
+		ionic_dbell_ring(q->lif->kern_dbpage, q->hw_type,
+				 q->dbval | q->head_idx);
+
+		q->dbell_jiffies = now;
+
+		dif = 2 * q->dbell_deadline;
+		if (dif > IONIC_RX_MAX_DOORBELL_DEADLINE)
+			dif = IONIC_RX_MAX_DOORBELL_DEADLINE;
+
+		q->dbell_deadline = dif;
+	}
+
+	return true;
+}
+
 static inline struct netdev_queue *q_to_ndq(struct ionic_queue *q)
 {
 	return netdev_get_tx_queue(q->lif->netdev, q->index);
···
 
 	ionic_dbell_ring(q->lif->kern_dbpage, q->hw_type,
 			 q->dbval | q->head_idx);
+
+	q->dbell_deadline = IONIC_RX_MIN_DOORBELL_DEADLINE;
+	q->dbell_jiffies = jiffies;
+
+	mod_timer(&q_to_qcq(q)->napi_qcq->napi_deadline,
+		  jiffies + IONIC_NAPI_DEADLINE);
 }
 
 void ionic_rx_empty(struct ionic_queue *q)
···
 				   work_done, flags);
 	}
 
+	if (!work_done && ionic_txq_poke_doorbell(&qcq->q))
+		mod_timer(&qcq->napi_deadline, jiffies + IONIC_NAPI_DEADLINE);
+
 	return work_done;
 }
 
···
 				   work_done, flags);
 	}
 
+	if (!work_done && ionic_rxq_poke_doorbell(&qcq->q))
+		mod_timer(&qcq->napi_deadline, jiffies + IONIC_NAPI_DEADLINE);
+
 	return work_done;
 }
 
 int ionic_txrx_napi(struct napi_struct *napi, int budget)
 {
-	struct ionic_qcq *qcq = napi_to_qcq(napi);
+	struct ionic_qcq *rxqcq = napi_to_qcq(napi);
 	struct ionic_cq *rxcq = napi_to_cq(napi);
 	unsigned int qi = rxcq->bound_q->index;
+	struct ionic_qcq *txqcq;
 	struct ionic_dev *idev;
 	struct ionic_lif *lif;
 	struct ionic_cq *txcq;
+	bool resched = false;
 	u32 rx_work_done = 0;
 	u32 tx_work_done = 0;
 	u32 flags = 0;
 
 	lif = rxcq->bound_q->lif;
 	idev = &lif->ionic->idev;
+	txqcq = lif->txqcqs[qi];
 	txcq = &lif->txqcqs[qi]->cq;
 
 	tx_work_done = ionic_cq_service(txcq, IONIC_TX_BUDGET_DEFAULT,
···
 	ionic_rx_fill(rxcq->bound_q);
 
 	if (rx_work_done < budget && napi_complete_done(napi, rx_work_done)) {
-		ionic_dim_update(qcq, 0);
+		ionic_dim_update(rxqcq, 0);
 		flags |= IONIC_INTR_CRED_UNMASK;
 		rxcq->bound_intr->rearm_count++;
 	}
···
 		ionic_intr_credits(idev->intr_ctrl, rxcq->bound_intr->index,
 				   tx_work_done + rx_work_done, flags);
 	}
+
+	if (!rx_work_done && ionic_rxq_poke_doorbell(&rxqcq->q))
+		resched = true;
+	if (!tx_work_done && ionic_txq_poke_doorbell(&txqcq->q))
+		resched = true;
+	if (resched)
+		mod_timer(&rxqcq->napi_deadline, jiffies + IONIC_NAPI_DEADLINE);
 
 	return rx_work_done;
 }