[Bug 220986] MediaTek MT7925 Bluetooth adapter (USB 13d3:3596) fails to initialize - reports as unsupported hardware variant 0x7902

[bugzilla-daemon@kernel.org]

https://bugzilla.kernel.org/show_bug.cgi?id=220986

Alex (aamolodc@gmail.com) changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |REOPENED
         Resolution|DUPLICATE                   |---

--- Comment #2 from Alex (aamolodc@gmail.com) ---
I respectfully request this bug be reopened as it represents a different issue
than bug #220682.

## Key Difference

**Bug #220682 (USB ID 0489:e111):**
- Bluetooth worked initially after boot
- Stopped working after GNOME login (timing-sensitive)
- Fixed by libmtp/libgphoto2 blacklist updates

**This bug #220986 (USB ID 13d3:3596):**
- Bluetooth NEVER initializes, even at boot
- Fails before GNOME login occurs
- NOT fixed by libmtp/libgphoto2 updates

## Testing Completed (2026-01-21)

I have installed the corrected package updates:
- libmtp-1.1.22-2.fc43.x86_64 (includes 13d3:3596 blacklist)
- libgphoto2-2.5.33-1.fc43.x86_64 (includes 13d3:3596 blacklist)

Performed full cold boot procedure:
1. Complete shutdown (not reboot)
2. Unplugged power for 30+ seconds
3. Booted directly to Linux (no Windows boot first)

## Current Status

Bluetooth still fails with identical error:

```
[   19.247336] Bluetooth: hci0: Opcode 0x0c03 failed: -110
```

System details:
- USB device detected: Bus 001 Device 003: ID 13d3:3596 IMC Networks
Wireless_Device
- btusb driver binds correctly to interfaces 0 and 1
- hci0 device created in /sys/class/bluetooth/
- Firmware exists: /lib/firmware/mediatek/mt7925/BT_RAM_CODE_MT7925_1_1_hdr.bin
- HCI_Reset command times out (error -110 = ETIMEDOUT)
- Chip does not respond to any HCI commands
- No firmware loading attempted (fails before that stage)

## Root Cause Analysis

The libmtp/libgphoto2 fix resolved the USB ID conflict, but a **second,
independent issue remains**: the btusb driver cannot communicate with the
MT7925 chip at the hardware level. The chip does not respond to HCI_Reset or
any other HCI commands.

This is a kernel driver initialization bug, not a userspace library conflict.

## Evidence This Is Different

1. **Timing:** Bug #220682 worked until login; this bug fails immediately at
boot
2. **No gvfs interaction:** Bluetooth fails before any GNOME services start
3. **Package updates don't help:** libmtp/libgphoto2 blacklists are installed
but issue persists
4. **Cold boot doesn't help:** Full power cycle completed, issue remains
5. **Hardware works:** Device functions correctly in Windows 11

## Request

Please reopen this bug as a separate kernel driver issue. The USB ID conflict
fix (bug #220682) is necessary but not sufficient to resolve this bug.

System: Fedora 43, Kernel 6.18.5-200.fc43.x86_64
Hardware: MediaTek MT7925 (USB ID 13d3:3596, AzureWave 6040 subsystem)

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