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, 7 insertions, 3 deletions

diff --git a/drivers/net/wireless/ath/ath10k/ahb.c b/drivers/net/wireless/ath/ath10k/ahb.c
index dede02668128..b99ad5df383d 100644
--- a/drivers/net/wireless/ath/ath10k/ahb.c
+++ b/drivers/net/wireless/ath/ath10k/ahb.c
@@ -462,13 +462,13 @@ static void ath10k_ahb_halt_chip(struct ath10k *ar)
 static irqreturn_t ath10k_ahb_interrupt_handler(int irq, void *arg)
 {
 	struct ath10k *ar = arg;
-	struct ath10k_pci *ar_pci = ath10k_pci_priv(ar);
 
 	if (!ath10k_pci_irq_pending(ar))
 		return IRQ_NONE;
 
 	ath10k_pci_disable_and_clear_legacy_irq(ar);
-	tasklet_schedule(&ar_pci->intr_tq);
+	ath10k_pci_irq_msi_fw_mask(ar);
+	napi_schedule(&ar->napi);
 
 	return IRQ_HANDLED;
 }
@@ -717,6 +717,9 @@ static void ath10k_ahb_hif_stop(struct ath10k *ar)
 	synchronize_irq(ar_ahb->irq);
 
 	ath10k_pci_flush(ar);
+
+	napi_synchronize(&ar->napi);
+	napi_disable(&ar->napi);
 }
 
 static int ath10k_ahb_hif_power_up(struct ath10k *ar)
@@ -748,6 +751,7 @@ static int ath10k_ahb_hif_power_up(struct ath10k *ar)
 		ath10k_err(ar, "could not wake up target CPU: %d\n", ret);
 		goto err_ce_deinit;
 	}
+	napi_enable(&ar->napi);
 
 	return 0;
 
@@ -831,7 +835,7 @@ static int ath10k_ahb_probe(struct platform_device *pdev)
 		goto err_resource_deinit;
 	}
 
-	ath10k_pci_init_irq_tasklets(ar);
+	ath10k_pci_init_napi(ar);
 
 	ret = ath10k_ahb_request_irq_legacy(ar);
 	if (ret)