wifi: mt76: mt792x: fix scheduler interference in drv own process

Add some time to wait for LP engine to complete its operation
before polling pmctrl register.

Signed-off-by: Michael Lo <michael.lo@mediatek.com>
Signed-off-by: Ming Yen Hsieh <mingyen.hsieh@mediatek.com>
Tested-by: David Ruth <druth@chromium.org>
Acked-by: Sean Wang <sean.wang@mediatek.com>
Link: https://patch.msgid.link/20240523112131.31437-1-mingyen.hsieh@mediatek.com
Signed-off-by: Felix Fietkau <nbd@nbd.name>

Author: michaello316

drivers/net/wireless/mediatek/mt76/mt76.h

@@ -1085,6 +1085,7 @@ bool ____mt76_poll_msec(struct mt76_dev *dev, u32 offset, u32 mask, u32 val,
 
 void mt76_mmio_init(struct mt76_dev *dev, void __iomem *regs);
 void mt76_pci_disable_aspm(struct pci_dev *pdev);
+bool mt76_pci_aspm_supported(struct pci_dev *pdev);
 
 static inline u16 mt76_chip(struct mt76_dev *dev)
 {

drivers/net/wireless/mediatek/mt76/mt7921/pci.c

@@ -339,6 +339,9 @@ static int mt7921_pci_probe(struct pci_dev *pdev,
 	bus_ops->rmw = mt7921_rmw;
 	dev->mt76.bus = bus_ops;
 
+	if (!mt7921_disable_aspm && mt76_pci_aspm_supported(pdev))
+		dev->aspm_supported = true;
+
 	ret = mt792xe_mcu_fw_pmctrl(dev);
 	if (ret)
 		goto err_free_dev;

drivers/net/wireless/mediatek/mt76/mt7925/pci.c

@@ -373,6 +373,9 @@ static int mt7925_pci_probe(struct pci_dev *pdev,
 	bus_ops->rmw = mt7925_rmw;
 	dev->mt76.bus = bus_ops;
 
+	if (!mt7925_disable_aspm && mt76_pci_aspm_supported(pdev))
+		dev->aspm_supported = true;
+
 	ret = __mt792x_mcu_fw_pmctrl(dev);
 	if (ret)
 		goto err_free_dev;

drivers/net/wireless/mediatek/mt76/mt792x.h

@@ -215,6 +215,7 @@ struct mt792x_dev {
 	bool fw_assert:1;
 	bool has_eht:1;
 	bool regd_in_progress:1;
+	bool aspm_supported:1;
 	wait_queue_head_t wait;
 
 	struct work_struct init_work;

drivers/net/wireless/mediatek/mt76/mt792x_core.c

@@ -809,6 +809,10 @@ int __mt792xe_mcu_drv_pmctrl(struct mt792x_dev *dev)
 
 	for (i = 0; i < MT792x_DRV_OWN_RETRY_COUNT; i++) {
 		mt76_wr(dev, MT_CONN_ON_LPCTL, PCIE_LPCR_HOST_CLR_OWN);
+
+		if (dev->aspm_supported)
+			usleep_range(2000, 3000);
+
 		if (mt76_poll_msec_tick(dev, MT_CONN_ON_LPCTL,
 					PCIE_LPCR_HOST_OWN_SYNC, 0, 50, 1))
 			break;

drivers/net/wireless/mediatek/mt76/pci.c

@@ -45,3 +45,26 @@ void mt76_pci_disable_aspm(struct pci_dev *pdev)
 					   aspm_conf);
 }
 EXPORT_SYMBOL_GPL(mt76_pci_disable_aspm);
+
+bool mt76_pci_aspm_supported(struct pci_dev *pdev)
+{
+	struct pci_dev *parent = pdev->bus->self;
+	u16 aspm_conf, parent_aspm_conf = 0;
+	bool result = true;
+
+	pcie_capability_read_word(pdev, PCI_EXP_LNKCTL, &aspm_conf);
+	aspm_conf &= PCI_EXP_LNKCTL_ASPMC;
+	if (parent) {
+		pcie_capability_read_word(parent, PCI_EXP_LNKCTL,
+					  &parent_aspm_conf);
+		parent_aspm_conf &= PCI_EXP_LNKCTL_ASPMC;
+	}
+
+	if (!aspm_conf && (!parent || !parent_aspm_conf)) {
+		/* aspm already disabled */
+		result = false;
+	}
+
+	return result;
+}
+EXPORT_SYMBOL_GPL(mt76_pci_aspm_supported);