[PATCH AUTOSEL 6.18-6.12] Bluetooth: btusb: MT7920: Add VID/PID 0489/e135

[Sasha Levin <sashal@kernel.org>]

From: Chris Lu <chris.lu@mediatek.com>

[ Upstream commit c126f98c011f5796ba118ef2093122d02809d30d ]

Add VID 0489 & PID e135 for MediaTek MT7920 USB Bluetooth chip.

The information in /sys/kernel/debug/usb/devices about the Bluetooth
device is listed as the below.

T:  Bus=06 Lev=01 Prnt=01 Port=00 Cnt=01 Dev#=  2 Spd=480  MxCh= 0
D:  Ver= 2.10 Cls=ef(misc ) Sub=02 Prot=01 MxPS=64 #Cfgs=  1
P:  Vendor=0489 ProdID=e135 Rev= 1.00
S:  Manufacturer=MediaTek Inc.
S:  Product=Wireless_Device
S:  SerialNumber=000000000
C:* #Ifs= 3 Cfg#= 1 Atr=e0 MxPwr=100mA
A:  FirstIf#= 0 IfCount= 3 Cls=e0(wlcon) Sub=01 Prot=01
I:* If#= 0 Alt= 0 #EPs= 3 Cls=e0(wlcon) Sub=01 Prot=01 Driver=btusb
E:  Ad=81(I) Atr=03(Int.) MxPS=  16 Ivl=125us
E:  Ad=82(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms
E:  Ad=02(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms
I:* If#= 1 Alt= 0 #EPs= 2 Cls=e0(wlcon) Sub=01 Prot=01 Driver=btusb
E:  Ad=83(I) Atr=01(Isoc) MxPS=   0 Ivl=1ms
E:  Ad=03(O) Atr=01(Isoc) MxPS=   0 Ivl=1ms
I:  If#= 1 Alt= 1 #EPs= 2 Cls=e0(wlcon) Sub=01 Prot=01 Driver=btusb
E:  Ad=83(I) Atr=01(Isoc) MxPS=   9 Ivl=1ms
E:  Ad=03(O) Atr=01(Isoc) MxPS=   9 Ivl=1ms
I:  If#= 1 Alt= 2 #EPs= 2 Cls=e0(wlcon) Sub=01 Prot=01 Driver=btusb
E:  Ad=83(I) Atr=01(Isoc) MxPS=  17 Ivl=1ms
E:  Ad=03(O) Atr=01(Isoc) MxPS=  17 Ivl=1ms
I:  If#= 1 Alt= 3 #EPs= 2 Cls=e0(wlcon) Sub=01 Prot=01 Driver=btusb
E:  Ad=83(I) Atr=01(Isoc) MxPS=  25 Ivl=1ms
E:  Ad=03(O) Atr=01(Isoc) MxPS=  25 Ivl=1ms
I:  If#= 1 Alt= 4 #EPs= 2 Cls=e0(wlcon) Sub=01 Prot=01 Driver=btusb
E:  Ad=83(I) Atr=01(Isoc) MxPS=  33 Ivl=1ms
E:  Ad=03(O) Atr=01(Isoc) MxPS=  33 Ivl=1ms
I:  If#= 1 Alt= 5 #EPs= 2 Cls=e0(wlcon) Sub=01 Prot=01 Driver=btusb
E:  Ad=83(I) Atr=01(Isoc) MxPS=  49 Ivl=1ms
E:  Ad=03(O) Atr=01(Isoc) MxPS=  49 Ivl=1ms
I:  If#= 1 Alt= 6 #EPs= 2 Cls=e0(wlcon) Sub=01 Prot=01 Driver=btusb
E:  Ad=83(I) Atr=01(Isoc) MxPS=  63 Ivl=1ms
E:  Ad=03(O) Atr=01(Isoc) MxPS=  63 Ivl=1ms
I:* If#= 2 Alt= 0 #EPs= 2 Cls=e0(wlcon) Sub=01 Prot=01 Driver=(none)
E:  Ad=8a(I) Atr=03(Int.) MxPS=  64 Ivl=125us
E:  Ad=0a(O) Atr=03(Int.) MxPS=  64 Ivl=125us
I:  If#= 2 Alt= 1 #EPs= 2 Cls=e0(wlcon) Sub=01 Prot=01 Driver=(none)
E:  Ad=8a(I) Atr=03(Int.) MxPS=  64 Ivl=125us
E:  Ad=0a(O) Atr=03(Int.) MxPS=  64 Ivl=125us

Signed-off-by: Chris Lu <chris.lu@mediatek.com>
Reviewed-by: Paul Menzel <pmenzel@molgen.mpg.de>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---

LLM Generated explanations, may be completely bogus:

## Commit Analysis: Bluetooth btusb MT7920 VID/PID Addition

### 1. COMMIT MESSAGE ANALYSIS

**Subject:** Adding a new USB VID/PID (0489/e135) for MediaTek MT7920
Bluetooth chip

**Key observations:**
- No `Cc: stable@vger.kernel.org` tag (not unusual for device ID
  additions)
- No `Fixes:` tag (not applicable - this enables new hardware, doesn't
  fix a bug)
- Author is from MediaTek (hardware vendor)
- Has `Reviewed-by` from Paul Menzel
- Signed off by Bluetooth maintainer Luiz Augusto von Dentz

### 2. CODE CHANGE ANALYSIS

The change is minimal:
```c
+       { USB_DEVICE(0x0489, 0xe135), .driver_info = BTUSB_MEDIATEK |
+
BTUSB_WIDEBAND_SPEECH },
```

This adds a single USB device ID entry to the `quirks_table[]` in
`drivers/bluetooth/btusb.c`. The entry:
- Uses VID 0x0489, PID 0xe135
- Uses identical flags to the adjacent MT7920 entry (0x0489, 0xe134)
- Follows the exact pattern of all other MediaTek device entries

### 3. CLASSIFICATION

This falls squarely into the **"NEW DEVICE IDs"** exception category for
stable backports. Per the stable kernel rules:

> Adding PCI IDs, USB IDs, ACPI IDs, etc. to existing drivers - These
are trivial one-line additions that enable hardware support

The btusb driver already fully supports MediaTek MT7920 devices; this
just adds recognition for a new variant.

### 4. SCOPE AND RISK ASSESSMENT

| Factor | Assessment |
|--------|------------|
| Lines changed | 2 (effectively 1 entry) |
| Files touched | 1 |
| Complexity | Trivial |
| Risk | Essentially zero |

**Risk justification:** This only affects devices with exactly
VID=0x0489 and PID=0xe135. It cannot cause regressions for any other
hardware. The change is purely additive with no modification to existing
functionality.

### 5. USER IMPACT

**Without this patch:** Users with MT7920 Bluetooth USB adapters using
this VID/PID combination have no Bluetooth functionality - the kernel
doesn't recognize their device.

**With this patch:** Bluetooth works normally using the mature, existing
MediaTek btusb support.

The USB device information in the commit message confirms this is real
hardware that users possess.

### 6. STABILITY INDICATORS

- ✅ Reviewed by Paul Menzel
- ✅ Signed off by Bluetooth subsystem maintainer
- ✅ Author from hardware vendor (MediaTek)
- ✅ Identical pattern to many existing entries
- ✅ Same flags used as sister device (e134)

### 7. DEPENDENCY CHECK

- **No dependencies** on other commits
- Uses existing macros (`USB_DEVICE`) and flags (`BTUSB_MEDIATEK`,
  `BTUSB_WIDEBAND_SPEECH`)
- The btusb driver with MediaTek MT7920 support exists in stable kernels

### CONCLUSION

This is a textbook stable-appropriate device ID addition:

1. **Trivial 2-line change** - lowest possible complexity
2. **Zero regression risk** - only affects one specific hardware variant
3. **Real user impact** - enables Bluetooth for users with this hardware
4. **Well-reviewed** - proper sign-offs from maintainer and vendor
5. **No new code** - leverages existing, mature MediaTek btusb support
6. **No dependencies** - applies cleanly to any kernel with MT7920
   support

Device ID additions like this are routinely backported to stable trees
because they provide clear value (enabling hardware) with essentially no
risk. The pattern is identical to dozens of similar entries in the same
file.

**YES**

 drivers/bluetooth/btusb.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/bluetooth/btusb.c b/drivers/bluetooth/btusb.c
index fa683bb7f0b49..595afeff4afb5 100644
--- a/drivers/bluetooth/btusb.c
+++ b/drivers/bluetooth/btusb.c
@@ -621,6 +621,8 @@ static const struct usb_device_id quirks_table[] = {
 	/* Additional MediaTek MT7920 Bluetooth devices */
 	{ USB_DEVICE(0x0489, 0xe134), .driver_info = BTUSB_MEDIATEK |
 						     BTUSB_WIDEBAND_SPEECH },
+	{ USB_DEVICE(0x0489, 0xe135), .driver_info = BTUSB_MEDIATEK |
+						     BTUSB_WIDEBAND_SPEECH },
 	{ USB_DEVICE(0x13d3, 0x3620), .driver_info = BTUSB_MEDIATEK |
 						     BTUSB_WIDEBAND_SPEECH },
 	{ USB_DEVICE(0x13d3, 0x3621), .driver_info = BTUSB_MEDIATEK |
-- 
2.51.0