[PATCH v5 1/8] Bluetooth: btmtk: Add MT6639 (MT7927) Bluetooth support

Javier Tia
2026-03-31T17:09:46Z

The MediaTek MT7927 (Filogic 380) combo WiFi 7 + BT 5.4 module uses
hardware variant 0x6639 for its Bluetooth subsystem. Without this patch,
the chip fails with "Unsupported hardware variant (00006639)" or hangs
during firmware download.

Three changes are needed to support MT6639:

1. CHIPID workaround: On some boards the BT USB MMIO register reads
0x0000 for dev_id, causing the driver to skip the 0x6639 init path.
Force dev_id to 0x6639 only when the USB VID/PID matches a known
MT6639 device, avoiding misdetection if a future chip also reads
zero. This follows the WiFi-side pattern that uses PCI device IDs
to scope the same workaround.

2. Firmware naming: MT6639 uses firmware version prefix "2_1" instead of
"1_1" used by MT7925 and other variants. The firmware path is
mediatek/mt7927/BT_RAM_CODE_MT6639_2_1_hdr.bin, using the mt7927
directory to match the WiFi firmware convention. The filename will
likely change to use MT7927 once MediaTek submits a dedicated
Linux firmware binary.

3. Section filtering: The MT6639 firmware binary contains 9 sections, but
only sections with (dlmodecrctype & 0xff) == 0x01 are Bluetooth-related.
Sending the remaining WiFi/other sections causes an irreversible BT
subsystem hang requiring a full power cycle. This matches the Windows
driver behavior observed via USB captures.

Also add 0x6639 to the reset register (CONNV3) and firmware setup switch
cases alongside the existing 0x7925 handling.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=221096
Link: https://github.com/openwrt/mt76/issues/927
Reported-by: Ryan Gilbert <xelnaga@gmail.com>
Signed-off-by: Javier Tia <floss@jetm.me>
---
drivers/bluetooth/btmtk.c | 60 +++++++++++++++++++++++++++++++++++++++----
drivers/bluetooth/btmtk.h | 7 +++--
drivers/bluetooth/btmtksdio.c | 2 +-
3 files changed, 61 insertions(+), 8 deletions(-)

diff --git a/drivers/bluetooth/btmtk.c b/drivers/bluetooth/btmtk.c
index 2507d587f28a..4af19b86c551 100644
--- a/drivers/bluetooth/btmtk.c
+++ b/drivers/bluetooth/btmtk.c
@@ -25,6 +25,22 @@
/* It is for mt79xx iso data transmission setting */
#define MTK_ISO_THRESHOLD 264

+/* Known MT6639 (MT7927) Bluetooth USB devices.
+ * Used to scope the zero-CHIPID workaround to real MT6639 hardware,
+ * since some boards return 0x0000 from the MMIO chip ID register.
+ */
+static const struct {
+ u16 vendor;
+ u16 product;
+} btmtk_mt6639_devs[] = {
+ { 0x0489, 0xe13a }, /* ASUS ROG Crosshair X870E Hero */
+ { 0x0489, 0xe0fa }, /* Lenovo Legion Pro 7 16ARX9 */
+ { 0x0489, 0xe10f }, /* Gigabyte Z790 AORUS MASTER X */
+ { 0x0489, 0xe110 }, /* MSI X870E Ace Max */
+ { 0x0489, 0xe116 }, /* TP-Link Archer TBE550E */
+ { 0x13d3, 0x3588 }, /* ASUS ROG STRIX X870E-E */
+};
+
struct btmtk_patch_header {
u8 datetime[16];
u8 platform[4];
@@ -112,7 +128,11 @@ static void btmtk_coredump_notify(struct hci_dev *hdev, int state)
void btmtk_fw_get_filename(char *buf, size_t size, u32 dev_id, u32 fw_ver,
u32 fw_flavor)
{
- if (dev_id == 0x7925)
+ if (dev_id == 0x6639)
+ snprintf(buf, size,
+ "mediatek/mt7927/BT_RAM_CODE_MT%04x_2_%x_hdr.bin",
+ dev_id & 0xffff, (fw_ver & 0xff) + 1);
+ else if (dev_id == 0x7925)
snprintf(buf, size,
"mediatek/mt%04x/BT_RAM_CODE_MT%04x_1_%x_hdr.bin",
dev_id & 0xffff, dev_id & 0xffff, (fw_ver & 0xff) + 1);
@@ -128,7 +148,8 @@ void btmtk_fw_get_filename(char *buf, size_t size, u32 dev_id, u32 fw_ver,
EXPORT_SYMBOL_GPL(btmtk_fw_get_filename);

int btmtk_setup_firmware_79xx(struct hci_dev *hdev, const char *fwname,
- wmt_cmd_sync_func_t wmt_cmd_sync)
+ wmt_cmd_sync_func_t wmt_cmd_sync,
+ u32 dev_id)
{
struct btmtk_hci_wmt_params wmt_params;
struct btmtk_patch_header *hdr;
@@ -166,6 +187,14 @@ int btmtk_setup_firmware_79xx(struct hci_dev *hdev, const char *fwname,
section_offset = le32_to_cpu(sectionmap->secoffset);
dl_size = le32_to_cpu(sectionmap->bin_info_spec.dlsize);

+ /* MT6639: only download sections where dlmode byte0 == 0x01,
+ * matching the Windows driver behavior which skips WiFi/other
+ * sections that would cause the chip to hang.
+ */
+ if (dev_id == 0x6639 && dl_size > 0 &&
+ (le32_to_cpu(sectionmap->bin_info_spec.dlmodecrctype) & 0xff) != 0x01)
+ continue;
+
if (dl_size > 0) {
retry = 20;
while (retry > 0) {
@@ -852,7 +881,7 @@ int btmtk_usb_subsys_reset(struct hci_dev *hdev, u32 dev_id)
if (err < 0)
return err;
msleep(100);
- } else if (dev_id == 0x7925) {
+ } else if (dev_id == 0x7925 || dev_id == 0x6639) {
err = btmtk_usb_uhw_reg_read(hdev, MTK_BT_RESET_REG_CONNV3, &val);
if (err < 0)
return err;
@@ -938,7 +967,7 @@ int btmtk_usb_subsys_reset(struct hci_dev *hdev, u32 dev_id)
}

err = btmtk_usb_id_get(hdev, 0x70010200, &val);
- if (err < 0 || !val)
+ if (err < 0 || (!val && dev_id != 0x6639))
bt_dev_err(hdev, "Can't get device id, subsys reset fail.");

return err;
@@ -1322,6 +1351,24 @@ int btmtk_usb_setup(struct hci_dev *hdev)
fw_flavor = (fw_flavor & 0x00000080) >> 7;
}

+ if (!dev_id) {
+ u16 vid = le16_to_cpu(btmtk_data->udev->descriptor.idVendor);
+ u16 pid = le16_to_cpu(btmtk_data->udev->descriptor.idProduct);
+ int i;
+
+ for (i = 0; i < ARRAY_SIZE(btmtk_mt6639_devs); i++) {
+ if (vid == btmtk_mt6639_devs[i].vendor &&
+ pid == btmtk_mt6639_devs[i].product) {
+ dev_id = 0x6639;
+ break;
+ }
+ }
+
+ if (dev_id)
+ bt_dev_info(hdev, "MT6639: CHIPID=0x0000 with VID=%04x PID=%04x, using 0x6639",
+ vid, pid);
+ }
+
btmtk_data->dev_id = dev_id;

err = btmtk_register_coredump(hdev, btmtk_data->drv_name, fw_version);
@@ -1339,11 +1386,13 @@ int btmtk_usb_setup(struct hci_dev *hdev)
case 0x7925:
case 0x7961:
case 0x7902:
+ case 0x6639:
btmtk_fw_get_filename(fw_bin_name, sizeof(fw_bin_name), dev_id,
fw_version, fw_flavor);

err = btmtk_setup_firmware_79xx(hdev, fw_bin_name,
- btmtk_usb_hci_wmt_sync);
+ btmtk_usb_hci_wmt_sync,
+ dev_id);
if (err < 0) {
/* retry once if setup firmware error */
if (!test_and_set_bit(BTMTK_FIRMWARE_DL_RETRY, &btmtk_data->flags))
@@ -1516,3 +1565,4 @@ MODULE_FIRMWARE(FIRMWARE_MT7668);
MODULE_FIRMWARE(FIRMWARE_MT7922);
MODULE_FIRMWARE(FIRMWARE_MT7961);
MODULE_FIRMWARE(FIRMWARE_MT7925);
+MODULE_FIRMWARE(FIRMWARE_MT7927);
diff --git a/drivers/bluetooth/btmtk.h b/drivers/bluetooth/btmtk.h
index adaf385626ee..c564aedc0ce0 100644
--- a/drivers/bluetooth/btmtk.h
+++ b/drivers/bluetooth/btmtk.h
@@ -8,6 +8,7 @@
#define FIRMWARE_MT7902 "mediatek/BT_RAM_CODE_MT7902_1_1_hdr.bin"
#define FIRMWARE_MT7961 "mediatek/BT_RAM_CODE_MT7961_1_2_hdr.bin"
#define FIRMWARE_MT7925 "mediatek/mt7925/BT_RAM_CODE_MT7925_1_1_hdr.bin"
+#define FIRMWARE_MT7927 "mediatek/mt7927/BT_RAM_CODE_MT6639_2_1_hdr.bin"

#define HCI_EV_WMT 0xe4
#define HCI_WMT_MAX_EVENT_SIZE 64
@@ -189,7 +190,8 @@ typedef int (*wmt_cmd_sync_func_t)(struct hci_dev *,
int btmtk_set_bdaddr(struct hci_dev *hdev, const bdaddr_t *bdaddr);

int btmtk_setup_firmware_79xx(struct hci_dev *hdev, const char *fwname,
- wmt_cmd_sync_func_t wmt_cmd_sync);
+ wmt_cmd_sync_func_t wmt_cmd_sync,
+ u32 dev_id);

int btmtk_setup_firmware(struct hci_dev *hdev, const char *fwname,
wmt_cmd_sync_func_t wmt_cmd_sync);
@@ -228,7 +230,8 @@ static inline int btmtk_set_bdaddr(struct hci_dev *hdev,

static inline int btmtk_setup_firmware_79xx(struct hci_dev *hdev,
const char *fwname,
- wmt_cmd_sync_func_t wmt_cmd_sync)
+ wmt_cmd_sync_func_t wmt_cmd_sync,
+ u32 dev_id)
{
return -EOPNOTSUPP;
}
diff --git a/drivers/bluetooth/btmtksdio.c b/drivers/bluetooth/btmtksdio.c
index 042064464d34..5b0fab7b89b5 100644
--- a/drivers/bluetooth/btmtksdio.c
+++ b/drivers/bluetooth/btmtksdio.c
@@ -883,7 +883,7 @@ static int mt79xx_setup(struct hci_dev *hdev, const char *fwname)
u8 param = 0x1;
int err;

- err = btmtk_setup_firmware_79xx(hdev, fwname, mtk_hci_wmt_sync);
+ err = btmtk_setup_firmware_79xx(hdev, fwname, mtk_hci_wmt_sync, 0);
if (err < 0) {
bt_dev_err(hdev, "Failed to setup 79xx firmware (%d)", err);
return err;

--
2.53.0