[PATCH] Bluetooth: btusb: deal with MT7925 invalid ISO RX packets

[Pauli Virtanen]

MT7925 produces empty ISO packets for Handle 0 when RX is active:

  > ISO Data RX: Handle 0 SN 36734 flags 0x00 dlen 0 slen 58  #851 [hci0]
  > ISO Data RX: Handle 0 SN 36734 flags 0x00 dlen 0 slen 58  #852 [hci0]

The driver should filter these out before passing to hci_core, otherwise
it will printk "Bluetooth: hci0: ISO packet for unknown connection
handle 0" errors.

Filter out by adding hdev->classify_pkt_type

Signed-off-by: Pauli Virtanen <pav at iki.fi>
---
 drivers/bluetooth/btmtk.c | 13 +++++++++++++
 drivers/bluetooth/btmtk.h |  8 ++++++++
 drivers/bluetooth/btusb.c |  1 +
 3 files changed, 22 insertions(+)

diff --git a/drivers/bluetooth/btmtk.c b/drivers/bluetooth/btmtk.c
index ab34f1dd42bc..9ba58cc9720a 100644
--- a/drivers/bluetooth/btmtk.c
+++ b/drivers/bluetooth/btmtk.c
@@ -1568,6 +1568,19 @@ int btmtk_recv_event(struct hci_dev *hdev, struct sk_buff *skb)
 	return hci_recv_frame(hdev, skb);
 }
 EXPORT_SYMBOL_GPL(btmtk_recv_event);
+
+u8 btmtk_classify_pkt_type(struct hci_dev *hdev, struct sk_buff *skb)
+{
+	/* MT7925 spams invalid ISO packets during ISO RX */
+	if (hci_skb_pkt_type(skb) == HCI_ISODATA_PKT &&
+	    skb->len == sizeof(struct hci_iso_hdr) &&
+	    hci_iso_hdr(skb)->handle == 0 &&
+	    hci_iso_hdr(skb)->dlen == 0)
+		return HCI_DIAG_PKT;
+
+	return hci_skb_pkt_type(skb);
+}
+EXPORT_SYMBOL_GPL(btmtk_classify_pkt_type);
 #endif
 
 MODULE_AUTHOR("Sean Wang <sean.wang at mediatek.com>");
diff --git a/drivers/bluetooth/btmtk.h b/drivers/bluetooth/btmtk.h
index c83c24897c95..e573b21cecf7 100644
--- a/drivers/bluetooth/btmtk.h
+++ b/drivers/bluetooth/btmtk.h
@@ -222,6 +222,8 @@ int btmtk_usb_setup(struct hci_dev *hdev);
 int btmtk_usb_shutdown(struct hci_dev *hdev);
 
 int btmtk_recv_event(struct hci_dev *hdev, struct sk_buff *skb);
+
+u8 btmtk_classify_pkt_type(struct hci_dev *hdev, struct sk_buff *skb);
 #else
 
 static inline int btmtk_set_bdaddr(struct hci_dev *hdev,
@@ -306,4 +308,10 @@ static inline int btmtk_recv_event(struct hci_dev *hdev, struct sk_buff *skb)
 {
 	return hci_recv_frame(hdev, skb);
 }
+
+static inline u8 btmtk_classify_pkt_type(struct hci_dev *hdev,
+					 struct sk_buff *skb)
+{
+	return hci_skb_pkt_type(skb);
+}
 #endif
diff --git a/drivers/bluetooth/btusb.c b/drivers/bluetooth/btusb.c
index a0a7da498466..7479928eec4b 100644
--- a/drivers/bluetooth/btusb.c
+++ b/drivers/bluetooth/btusb.c
@@ -4245,6 +4245,7 @@ static int btusb_probe(struct usb_interface *intf,
 		hdev->reset = btmtk_reset_sync;
 		hdev->set_bdaddr = btmtk_set_bdaddr;
 		hdev->send = btusb_send_frame_mtk;
+		hdev->classify_pkt_type = btmtk_classify_pkt_type;
 		hci_set_quirk(hdev, HCI_QUIRK_BROKEN_ENHANCED_SETUP_SYNC_CONN);
 		hci_set_quirk(hdev, HCI_QUIRK_NON_PERSISTENT_SETUP);
 		data->recv_acl = btmtk_usb_recv_acl;
-- 
2.53.0