ath10k: implement NAPI support

Add NAPI support for rx and tx completion. NAPI poll is scheduled
from interrupt handler. The design is as below

 - on interrupt
     - schedule napi and mask interrupts
 - on poll
   - process all pipes (no actual Tx/Rx)
   - process Rx within budget
   - if quota exceeds budget reschedule napi poll by returning budget
   - process Tx completions and update budget if necessary
   - process Tx fetch indications (pull-push)
   - push any other pending Tx (if possible)
   - before resched or napi completion replenish htt rx ring buffer
   - if work done < budget, complete napi poll and unmask interrupts

This change also get rid of two tasklets (intr_tq and txrx_compl_task).

Measured peak throughput with NAPI on IPQ4019 platform in controlled
environment. No noticeable reduction in throughput is seen and also
observed improvements in CPU usage. Approx. 15% CPU usage got reduced
in UDP uplink case.

DL: AP DUT Tx
UL: AP DUT Rx

IPQ4019 (avg. cpu usage %)

========
                TOT              +NAPI
              ===========      =============
TCP DL       644 Mbps (42%)    645 Mbps (36%)
TCP UL       673 Mbps (30%)    675 Mbps (26%)
UDP DL       682 Mbps (49%)    680 Mbps (49%)
UDP UL       720 Mbps (28%)    717 Mbps (11%)

Signed-off-by: Rajkumar Manoharan <rmanohar@qti.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

1 files changed, 45 insertions, 26 deletions

diff --git a/drivers/net/wireless/ath/ath10k/pci.c b/drivers/net/wireless/ath/ath10k/pci.c
index 1b841ad..930e951 100644
--- a/drivers/net/wireless/ath/ath10k/pci.c
+++ b/drivers/net/wireless/ath/ath10k/pci.c
@@ -1506,12 +1506,10 @@ void ath10k_pci_hif_send_complete_check(struct ath10k *ar, u8 pipe,
 	ath10k_ce_per_engine_service(ar, pipe);
 }
 
-void ath10k_pci_kill_tasklet(struct ath10k *ar)
+static void ath10k_pci_rx_retry_sync(struct ath10k *ar)
 {
 	struct ath10k_pci *ar_pci = ath10k_pci_priv(ar);
 
-	tasklet_kill(&ar_pci->intr_tq);
-
 	del_timer_sync(&ar_pci->rx_post_retry);
 }
 
@@ -1570,7 +1568,7 @@ void ath10k_pci_hif_get_default_pipe(struct ath10k *ar,
 						 ul_pipe, dl_pipe);
 }
 
-static void ath10k_pci_irq_msi_fw_mask(struct ath10k *ar)
+void ath10k_pci_irq_msi_fw_mask(struct ath10k *ar)
 {
 	u32 val;
 
@@ -1753,7 +1751,7 @@ void ath10k_pci_ce_deinit(struct ath10k *ar)
 
 void ath10k_pci_flush(struct ath10k *ar)
 {
-	ath10k_pci_kill_tasklet(ar);
+	ath10k_pci_rx_retry_sync(ar);
 	ath10k_pci_buffer_cleanup(ar);
 }
 
@@ -1780,6 +1778,8 @@ static void ath10k_pci_hif_stop(struct ath10k *ar)
 	ath10k_pci_irq_disable(ar);
 	ath10k_pci_irq_sync(ar);
 	ath10k_pci_flush(ar);
+	napi_synchronize(&ar->napi);
+	napi_disable(&ar->napi);
 
 	spin_lock_irqsave(&ar_pci->ps_lock, flags);
 	WARN_ON(ar_pci->ps_wake_refcount > 0);
@@ -2533,6 +2533,7 @@ static int ath10k_pci_hif_power_up(struct ath10k *ar)
 		ath10k_err(ar, "could not wake up target CPU: %d\n", ret);
 		goto err_ce;
 	}
+	napi_enable(&ar->napi);
 
 	return 0;
 
@@ -2772,35 +2773,53 @@ static irqreturn_t ath10k_pci_interrupt_handler(int irq, void *arg)
 		return IRQ_NONE;
 	}
 
-	if (ar_pci->oper_irq_mode == ATH10K_PCI_IRQ_LEGACY) {
-		if (!ath10k_pci_irq_pending(ar))
-			return IRQ_NONE;
-
-		ath10k_pci_disable_and_clear_legacy_irq(ar);
-	}
+	if ((ar_pci->oper_irq_mode == ATH10K_PCI_IRQ_LEGACY) &&
+	    !ath10k_pci_irq_pending(ar))
+		return IRQ_NONE;
 
-	tasklet_schedule(&ar_pci->intr_tq);
+	ath10k_pci_disable_and_clear_legacy_irq(ar);
+	ath10k_pci_irq_msi_fw_mask(ar);
+	napi_schedule(&ar->napi);
 
 	return IRQ_HANDLED;
 }
 
-static void ath10k_pci_tasklet(unsigned long data)
+static int ath10k_pci_napi_poll(struct napi_struct *ctx, int budget)
 {
-	struct ath10k *ar = (struct ath10k *)data;
-	struct ath10k_pci *ar_pci = ath10k_pci_priv(ar);
+	struct ath10k *ar = container_of(ctx, struct ath10k, napi);
+	int done = 0;
 
 	if (ath10k_pci_has_fw_crashed(ar)) {
-		ath10k_pci_irq_disable(ar);
 		ath10k_pci_fw_crashed_clear(ar);
 		ath10k_pci_fw_crashed_dump(ar);
-		return;
+		napi_complete(ctx);
+		return done;
 	}
 
 	ath10k_ce_per_engine_service_any(ar);
 
-	/* Re-enable legacy irq that was disabled in the irq handler */
-	if (ar_pci->oper_irq_mode == ATH10K_PCI_IRQ_LEGACY)
+	done = ath10k_htt_txrx_compl_task(ar, budget);
+
+	if (done < budget) {
+		napi_complete(ctx);
+		/* In case of MSI, it is possible that interrupts are received
+		 * while NAPI poll is inprogress. So pending interrupts that are
+		 * received after processing all copy engine pipes by NAPI poll
+		 * will not be handled again. This is causing failure to
+		 * complete boot sequence in x86 platform. So before enabling
+		 * interrupts safer to check for pending interrupts for
+		 * immediate servicing.
+		 */
+		if (CE_INTERRUPT_SUMMARY(ar)) {
+			napi_reschedule(ctx);
+			goto out;
+		}
 		ath10k_pci_enable_legacy_irq(ar);
+		ath10k_pci_irq_msi_fw_unmask(ar);
+	}
+
+out:
+	return done;
 }
 
 static int ath10k_pci_request_irq_msi(struct ath10k *ar)
@@ -2858,11 +2877,10 @@ static void ath10k_pci_free_irq(struct ath10k *ar)
 	free_irq(ar_pci->pdev->irq, ar);
 }
 
-void ath10k_pci_init_irq_tasklets(struct ath10k *ar)
+void ath10k_pci_init_napi(struct ath10k *ar)
 {
-	struct ath10k_pci *ar_pci = ath10k_pci_priv(ar);
-
-	tasklet_init(&ar_pci->intr_tq, ath10k_pci_tasklet, (unsigned long)ar);
+	netif_napi_add(&ar->napi_dev, &ar->napi, ath10k_pci_napi_poll,
+		       ATH10K_NAPI_BUDGET);
 }
 
 static int ath10k_pci_init_irq(struct ath10k *ar)
@@ -2870,7 +2888,7 @@ static int ath10k_pci_init_irq(struct ath10k *ar)
 	struct ath10k_pci *ar_pci = ath10k_pci_priv(ar);
 	int ret;
 
-	ath10k_pci_init_irq_tasklets(ar);
+	ath10k_pci_init_napi(ar);
 
 	if (ath10k_pci_irq_mode != ATH10K_PCI_IRQ_AUTO)
 		ath10k_info(ar, "limiting irq mode to: %d\n",
@@ -3131,7 +3149,8 @@ int ath10k_pci_setup_resource(struct ath10k *ar)
 
 void ath10k_pci_release_resource(struct ath10k *ar)
 {
-	ath10k_pci_kill_tasklet(ar);
+	ath10k_pci_rx_retry_sync(ar);
+	netif_napi_del(&ar->napi);
 	ath10k_pci_ce_deinit(ar);
 	ath10k_pci_free_pipes(ar);
 }
@@ -3298,7 +3317,7 @@ static int ath10k_pci_probe(struct pci_dev *pdev,
 
 err_free_irq:
 	ath10k_pci_free_irq(ar);
-	ath10k_pci_kill_tasklet(ar);
+	ath10k_pci_rx_retry_sync(ar);
 
 err_deinit_irq:
 	ath10k_pci_deinit_irq(ar);