rtw89: pci: add a separate interrupt handler for low power mode

In lower power mode, there are very low amount of RX, and it must process
in a separated function instead of schedule_napi(), because the existing
napi_poll does many things to optimize performance, but not all registers
can access in low power mode. The simple way is to use threadfn to process
the simple thing.
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20220421120903.73715-5-pkshih@realtek.com

drivers/net/wireless/realtek/rtw89/core.c

@@ -1420,7 +1420,10 @@ static void rtw89_core_rx_to_mac80211(struct rtw89_dev *rtwdev,
 {
 	rtw89_core_hw_to_sband_rate(rx_status);
 	rtw89_core_rx_stats(rtwdev, phy_ppdu, desc_info, skb_ppdu);
+	/* In low power mode, it does RX in thread context. */
+	local_bh_disable();
 	ieee80211_rx_napi(rtwdev->hw, NULL, skb_ppdu, &rtwdev->napi);
+	local_bh_enable();
 	rtwdev->napi_budget_countdown--;
 }
 

drivers/net/wireless/realtek/rtw89/pci.c

@@ -713,6 +713,18 @@ static void rtw89_pci_ops_recovery_complete(struct rtw89_dev *rtwdev)
 	spin_unlock_irqrestore(&rtwpci->irq_lock, flags);
 }
 
+static void rtw89_pci_low_power_interrupt_handler(struct rtw89_dev *rtwdev)
+{
+	struct rtw89_pci *rtwpci = (struct rtw89_pci *)rtwdev->priv;
+	int budget = NAPI_POLL_WEIGHT;
+
+	/* To prevent RXQ get stuck due to run out of budget. */
+	rtwdev->napi_budget_countdown = budget;
+
+	rtw89_pci_poll_rpq_dma(rtwdev, rtwpci, budget);
+	rtw89_pci_poll_rxq_dma(rtwdev, rtwpci, budget);
+}
+
 static irqreturn_t rtw89_pci_interrupt_threadfn(int irq, void *dev)
 {
 	struct rtw89_dev *rtwdev = dev;
@@ -733,6 +745,11 @@ static irqreturn_t rtw89_pci_interrupt_threadfn(int irq, void *dev)
 	if (unlikely(rtwpci->under_recovery))
 		return IRQ_HANDLED;
 
+	if (unlikely(rtwpci->low_power)) {
+		rtw89_pci_low_power_interrupt_handler(rtwdev);
+		goto enable_intr;
+	}
+
 	if (likely(rtwpci->running)) {
 		local_bh_disable();
 		napi_schedule(&rtwdev->napi);
@@ -740,6 +757,12 @@ static irqreturn_t rtw89_pci_interrupt_threadfn(int irq, void *dev)
 	}
 
 	return IRQ_HANDLED;
+
+enable_intr:
+	spin_lock_irqsave(&rtwpci->irq_lock, flags);
+	rtw89_chip_enable_intr(rtwdev, rtwpci);
+	spin_unlock_irqrestore(&rtwpci->irq_lock, flags);
+	return IRQ_HANDLED;
 }
 
 static irqreturn_t rtw89_pci_interrupt_handler(int irq, void *dev)