T99W709 is designed based on MTK T300(5G redcap) chip. There are
7 serial ports to be enumerated: AP_LOG, GNSS, AP_META, AT,
MD_META, NPT, DBG. RSVD(5) for ADB port.

test evidence as below:
T:  Bus=01 Lev=02 Prnt=02 Port=00 Cnt=01 Dev#=  7 Spd=480 MxCh= 0
D:  Ver= 2.10 Cls=ef(misc ) Sub=02 Prot=01 MxPS=64 #Cfgs=  1
P:  Vendor=0489 ProdID=e15f Rev=00.01
S:  Manufacturer=MediaTek Inc.
S:  Product=USB DATA CARD
S:  SerialNumber=355511220000399
C:  #Ifs=10 Cfg#= 1 Atr=a0 MxPwr=500mA
I:  If#=0x0 Alt= 0 #EPs= 1 Cls=02(commc) Sub=0e Prot=00 Driver=cdc_mbim
I:  If#=0x1 Alt= 1 #EPs= 2 Cls=0a(data ) Sub=00 Prot=02 Driver=cdc_mbim
I:  If#=0x2 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=00 Prot=00 Driver=option
I:  If#=0x3 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=00 Prot=00 Driver=option
I:  If#=0x4 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=00 Prot=00 Driver=option
I:  If#=0x5 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=42 Prot=01 Driver=usbfs
I:  If#=0x6 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=00 Prot=00 Driver=option
I:  If#=0x7 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=00 Prot=00 Driver=option
I:  If#=0x8 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=00 Prot=00 Driver=option
I:  If#=0x9 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=00 Prot=00 Driver=option

Signed-off-by: Slark Xiao <slark_xiao@163.com>
---
 drivers/usb/serial/option.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/usb/serial/option.c b/drivers/usb/serial/option.c
index 147ca50c94be..1fc7ee5fa91d 100644
--- a/drivers/usb/serial/option.c
+++ b/drivers/usb/serial/option.c
@@ -2348,6 +2348,8 @@ static const struct usb_device_id option_ids[] = {
 	  .driver_info = RSVD(5) | RSVD(6) },
 	{ USB_DEVICE_INTERFACE_CLASS(0x0489, 0xe167, 0xff),                     /* Foxconn T99W640 MBIM */
 	  .driver_info = RSVD(3) },
+	{ USB_DEVICE_INTERFACE_CLASS(0x0489, 0xe15f, 0xff),                     /* Foxconn T99W709 */
+	  .driver_info = RSVD(5) },
 	{ USB_DEVICE(0x1508, 0x1001),						/* Fibocom NL668 (IOT version) */
 	  .driver_info = RSVD(4) | RSVD(5) | RSVD(6) },
 	{ USB_DEVICE(0x1782, 0x4d10) },						/* Fibocom L610 (AT mode) */
-- 
2.25.1

On Mon, Jul 21, 2025 at 07:39:19PM +0800, Slark Xiao wrote:
> T99W709 is designed based on MTK T300(5G redcap) chip. There are
> 7 serial ports to be enumerated: AP_LOG, GNSS, AP_META, AT,
> MD_META, NPT, DBG. RSVD(5) for ADB port.

Applied, thanks.

Johan