[PATCH 2/2] wifi: mt76: mt7921u: escalate broken USB transport to device reset

[Sean Wang <sean.wang@kernel.org>]

From: Sean Wang <sean.wang@mediatek.com>

Check the USB control path before running the normal WFSYS reset flow.

If USB access is no longer reliable, stop the WFSYS-only reset path,
mark the device as bus_hung, and queue a USB device reset instead.

Reuse the existing bus_hung state to represent transport-level failure,
keeping the semantics consistent with the SDIO path.

Also initialize bus_hung explicitly during probe for consistency.

Signed-off-by: Sean Wang <sean.wang@mediatek.com>
---
 .../net/wireless/mediatek/mt76/mt7921/mac.c   |  4 ++-
 .../net/wireless/mediatek/mt76/mt7921/usb.c   |  5 ++++
 drivers/net/wireless/mediatek/mt76/mt792x.h   |  1 +
 .../net/wireless/mediatek/mt76/mt792x_usb.c   | 26 +++++++++++++++++++
 4 files changed, 35 insertions(+), 1 deletion(-)

diff --git a/drivers/net/wireless/mediatek/mt76/mt7921/mac.c b/drivers/net/wireless/mediatek/mt76/mt7921/mac.c
index 03b4960db73f..d27dbee8df1b 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7921/mac.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7921/mac.c
@@ -675,7 +675,9 @@ void mt7921_mac_reset_work(struct work_struct *work)
 		if (!ret)
 			break;
 	}
-	if (mt76_is_sdio(&dev->mt76) && atomic_read(&dev->mt76.bus_hung))
+
+	if ((mt76_is_sdio(&dev->mt76) || mt76_is_usb(&dev->mt76)) &&
+	    atomic_read(&dev->mt76.bus_hung))
 		return;
 
 	if (i == 10)
diff --git a/drivers/net/wireless/mediatek/mt76/mt7921/usb.c b/drivers/net/wireless/mediatek/mt76/mt7921/usb.c
index 6be28f4152ed..8c0f0e4ef87b 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7921/usb.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7921/usb.c
@@ -88,6 +88,10 @@ static int mt7921u_mac_reset(struct mt792x_dev *dev)
 {
 	int err;
 
+	mt792xu_reset_on_bus_error(dev);
+	if (atomic_read(&dev->mt76.bus_hung))
+		return 0;
+
 	mt76_txq_schedule_all(&dev->mphy);
 	mt76_worker_disable(&dev->mt76.tx_worker);
 
@@ -196,6 +200,7 @@ static int mt7921u_probe(struct usb_interface *usb_intf,
 	dev = container_of(mdev, struct mt792x_dev, mt76);
 	dev->fw_features = features;
 	dev->hif_ops = &hif_ops;
+	atomic_set(&dev->mt76.bus_hung, false);
 	mt792xu_reset_work_init(dev);
 
 	udev = usb_get_dev(udev);
diff --git a/drivers/net/wireless/mediatek/mt76/mt792x.h b/drivers/net/wireless/mediatek/mt76/mt792x.h
index 5f06074591ca..74222c507b81 100644
--- a/drivers/net/wireless/mediatek/mt76/mt792x.h
+++ b/drivers/net/wireless/mediatek/mt76/mt792x.h
@@ -494,6 +494,7 @@ int mt792xu_init_reset(struct mt792x_dev *dev);
 void mt792xu_reset_work_init(struct mt792x_dev *dev);
 void mt792xu_reset_work_cleanup(struct mt792x_dev *dev);
 int mt792xu_check_bus(struct mt792x_dev *dev);
+int mt792xu_reset_on_bus_error(struct mt792x_dev *dev);
 u32 mt792xu_rr(struct mt76_dev *dev, u32 addr);
 void mt792xu_wr(struct mt76_dev *dev, u32 addr, u32 val);
 u32 mt792xu_rmw(struct mt76_dev *dev, u32 addr, u32 mask, u32 val);
diff --git a/drivers/net/wireless/mediatek/mt76/mt792x_usb.c b/drivers/net/wireless/mediatek/mt76/mt792x_usb.c
index 2558d87b1e0f..6b10d035bcbc 100644
--- a/drivers/net/wireless/mediatek/mt76/mt792x_usb.c
+++ b/drivers/net/wireless/mediatek/mt76/mt792x_usb.c
@@ -60,6 +60,32 @@ int mt792xu_check_bus(struct mt792x_dev *dev)
 }
 EXPORT_SYMBOL_GPL(mt792xu_check_bus);
 
+int mt792xu_reset_on_bus_error(struct mt792x_dev *dev)
+{
+	int err = 0;
+
+	if (!atomic_read(&dev->mt76.bus_hung))
+		err = mt792xu_check_bus(dev);
+
+	if (err) {
+		atomic_set(&dev->mt76.bus_hung, true);
+
+		if (!atomic_xchg(&dev->usb_reset_pending, 1)) {
+			dev_warn(dev->mt76.dev,
+				 "USB transport access failed (%d), queueing device reset\n",
+				 err);
+
+			schedule_work(&dev->usb_reset_work);
+		}
+
+		return err;
+	}
+
+	atomic_set(&dev->mt76.bus_hung, false);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(mt792xu_reset_on_bus_error);
+
 u32 mt792xu_rr(struct mt76_dev *dev, u32 addr)
 {
 	u32 ret;
-- 
2.43.0