diff -drupN a/drivers/bluetooth/hci_h4.c b/drivers/bluetooth/hci_h4.c
--- a/drivers/bluetooth/hci_h4.c	2018-08-06 17:23:04.000000000 +0300
+++ b/drivers/bluetooth/hci_h4.c	2022-06-12 05:28:14.000000000 +0300
@@ -44,14 +44,30 @@
 
 #include <net/bluetooth/bluetooth.h>
 #include <net/bluetooth/hci_core.h>
+#include <linux/version.h>
 
 #include "hci_uart.h"
 
+#ifdef BTCOEX
+#include "rtk_coex.h"
+#endif
+
+//#define VERSION "1.2"
+
 struct h4_struct {
+	unsigned long rx_state;
+	unsigned long rx_count;
 	struct sk_buff *rx_skb;
 	struct sk_buff_head txq;
 };
 
+/* H4 receiver States */
+#define H4_W4_PACKET_TYPE	0
+#define H4_W4_EVENT_HDR		1
+#define H4_W4_ACL_HDR		2
+#define H4_W4_SCO_HDR		3
+#define H4_W4_DATA		4
+
 /* Initialize protocol */
 static int h4_open(struct hci_uart *hu)
 {
@@ -120,21 +136,168 @@ static const struct h4_recv_pkt h4_recv_
 	{ H4_RECV_EVENT, .recv = hci_recv_frame },
 };
 
+#if HCI_VERSION_CODE < KERNEL_VERSION(3, 13, 0)
+static inline int h4_check_data_len(struct h4_struct *h4, int len)
+#else
+static inline int h4_check_data_len(struct hci_dev *hdev, struct h4_struct *h4, int len)
+#endif
+{
+	register int room = skb_tailroom(h4->rx_skb);
+
+	BT_DBG("len %d room %d", len, room);
+
+	if (!len) {
+#if HCI_VERSION_CODE < KERNEL_VERSION(3, 13, 0)
+		hci_recv_frame(h4->rx_skb);
+#else
+		hci_recv_frame(hdev, h4->rx_skb);
+#endif
+	} else if (len > room) {
+		BT_ERR("Data length is too large");
+		kfree_skb(h4->rx_skb);
+	} else {
+		h4->rx_state = H4_W4_DATA;
+		h4->rx_count = len;
+		return len;
+	}
+
+	h4->rx_state = H4_W4_PACKET_TYPE;
+	h4->rx_skb   = NULL;
+	h4->rx_count = 0;
+
+	return 0;
+}
+
 /* Recv data */
 static int h4_recv(struct hci_uart *hu, const void *data, int count)
 {
 	struct h4_struct *h4 = hu->priv;
+	register char *ptr;
+	struct hci_event_hdr *eh;
+	struct hci_acl_hdr   *ah;
+	struct hci_sco_hdr   *sh;
+	register int len, type, dlen;
 
-	if (!test_bit(HCI_UART_REGISTERED, &hu->flags))
-		return -EUNATCH;
+	BT_DBG("hu %p count %d rx_state %ld rx_count %ld",
+			hu, count, h4->rx_state, h4->rx_count);
 
-	h4->rx_skb = h4_recv_buf(hu->hdev, h4->rx_skb, data, count,
-				 h4_recv_pkts, ARRAY_SIZE(h4_recv_pkts));
-	if (IS_ERR(h4->rx_skb)) {
-		int err = PTR_ERR(h4->rx_skb);
-		BT_ERR("%s: Frame reassembly failed (%d)", hu->hdev->name, err);
-		h4->rx_skb = NULL;
-		return err;
+	ptr = data;
+	while (count) {
+		if (h4->rx_count) {
+			len = min_t(unsigned int, h4->rx_count, count);
+			memcpy(skb_put(h4->rx_skb, len), ptr, len);
+			h4->rx_count -= len; count -= len; ptr += len;
+
+			if (h4->rx_count)
+				continue;
+
+			switch (h4->rx_state) {
+			case H4_W4_DATA:
+				BT_DBG("Complete data");
+#ifdef BTCOEX
+				if (bt_cb(h4->rx_skb)->pkt_type == HCI_EVENT_PKT)
+					rtk_btcoex_parse_event(
+							h4->rx_skb->data,
+							h4->rx_skb->len);
+
+				if (bt_cb(h4->rx_skb)->pkt_type == HCI_ACLDATA_PKT)
+					rtk_btcoex_parse_l2cap_data_rx(
+							h4->rx_skb->data,
+							h4->rx_skb->len);
+#endif
+
+#if HCI_VERSION_CODE < KERNEL_VERSION(3, 13, 0)
+				hci_recv_frame(h4->rx_skb);
+#else
+				hci_recv_frame(hu->hdev, h4->rx_skb);
+#endif
+
+				h4->rx_state = H4_W4_PACKET_TYPE;
+				h4->rx_skb = NULL;
+				continue;
+
+			case H4_W4_EVENT_HDR:
+				eh = hci_event_hdr(h4->rx_skb);
+
+				BT_DBG("Event header: evt 0x%2.2x plen %d", eh->evt, eh->plen);
+
+#if HCI_VERSION_CODE < KERNEL_VERSION(3, 13, 0)
+				h4_check_data_len(h4, eh->plen);
+#else
+				h4_check_data_len(hu->hdev, h4, eh->plen);
+#endif
+				continue;
+
+			case H4_W4_ACL_HDR:
+				ah = hci_acl_hdr(h4->rx_skb);
+				dlen = __le16_to_cpu(ah->dlen);
+
+				BT_DBG("ACL header: dlen %d", dlen);
+
+#if HCI_VERSION_CODE < KERNEL_VERSION(3, 13, 0)
+				h4_check_data_len(h4, dlen);
+#else
+				h4_check_data_len(hu->hdev, h4, dlen);
+#endif
+				continue;
+
+			case H4_W4_SCO_HDR:
+				sh = hci_sco_hdr(h4->rx_skb);
+
+				BT_DBG("SCO header: dlen %d", sh->dlen);
+
+#if HCI_VERSION_CODE < KERNEL_VERSION(3, 13, 0)
+				h4_check_data_len(h4, sh->dlen);
+#else
+				h4_check_data_len(hu->hdev, h4, sh->dlen);
+#endif
+				continue;
+			}
+		}
+
+		/* H4_W4_PACKET_TYPE */
+		switch (*ptr) {
+		case HCI_EVENT_PKT:
+			BT_DBG("Event packet");
+			h4->rx_state = H4_W4_EVENT_HDR;
+			h4->rx_count = HCI_EVENT_HDR_SIZE;
+			type = HCI_EVENT_PKT;
+			break;
+
+		case HCI_ACLDATA_PKT:
+			BT_DBG("ACL packet");
+			h4->rx_state = H4_W4_ACL_HDR;
+			h4->rx_count = HCI_ACL_HDR_SIZE;
+			type = HCI_ACLDATA_PKT;
+			break;
+
+		case HCI_SCODATA_PKT:
+			BT_DBG("SCO packet");
+			h4->rx_state = H4_W4_SCO_HDR;
+			h4->rx_count = HCI_SCO_HDR_SIZE;
+			type = HCI_SCODATA_PKT;
+			break;
+
+		default:
+			BT_ERR("Unknown HCI packet type %2.2x", (__u8)*ptr);
+			hu->hdev->stat.err_rx++;
+			ptr++; count--;
+			continue;
+		};
+
+		ptr++; count--;
+
+		/* Allocate packet */
+		h4->rx_skb = bt_skb_alloc(HCI_MAX_FRAME_SIZE, GFP_ATOMIC);
+		if (!h4->rx_skb) {
+			BT_ERR("Can't allocate mem for new packet");
+			h4->rx_state = H4_W4_PACKET_TYPE;
+			h4->rx_count = 0;
+			return -ENOMEM;
+		}
+
+		h4->rx_skb->dev = (void *) hu->hdev;
+		bt_cb(h4->rx_skb)->pkt_type = type;
 	}
 
 	return count;
@@ -159,7 +322,14 @@ static const struct hci_uart_proto h4p =
 
 int __init h4_init(void)
 {
-	return hci_uart_register_proto(&h4p);
+	int err = hci_uart_register_proto(&h4p);
+
+	if (!err)
+		BT_INFO("HCI H4 protocol initialized");
+	else
+		BT_ERR("HCI H4 protocol registration failed");
+
+	return err;
 }
 
 int __exit h4_deinit(void)