Broadcom Bluetooth

Resources

broadcom-bt-firmware homepage

This article details setup for Broadcom Bluetooth 4.x devices mostly based on BCM20702, BCM4354, and BCM4356 chipsets. These bluetooth chipsets are also used in various devices including USB-dongles, hybrid WIFI+Bluetooth embedded chipsets, etc.

Hardware

Mostly complete list of supported devices can be found upstream.

Device	Make/model	Status	Vendor ID / Product ID	Kernel driver(s)	Kernel version	Notes
USB Dongle	Asus BT-400 USB	Works	0b05:17cb	btbcm	4.2	Requires firmware
USB Dongle	Targus ACB75AU	Works	0a5c:21e8	btbcm	3.4+	Requires firmware brcm/BCM20702A1-0a5c-21e8.hcd

Security considerations

Recently several vulnerabilities have been discovered in the Bluetooth stack such as CVE-2018-5383, CVE-2019-9506 (KNOB), CVE-2020-10135 (BIAS) and others. Since Broadcom has stopped active support for its consumer devices, systems utilizing this software may be subject to security risks. It is wise to assess the risk before moving forward, since the repository maintainer cannot provide security fixes.

Installation

Kernel

Broadcom Bluetooth devices require the btbcm kernel module, which can be built with these kernel options:

KERNEL Broadcom Bluetooth support

[*] Networking support  --->
    <M>   Bluetooth subsystem support  --->
        Bluetooth device drivers  --->
            <M> HCI USB driver
            [*]   Broadcom protocol support
            [*] Broadcom protocol support

Firmware

Mostly Broadcom Bluetooth stack requires external firmware, supplied with Windows drivers. This can be verified by using following commands:

user $dmesg | grep -i bluetooth

Bluetooth: hci1: BCM: chip id 63
Bluetooth: hci1: BCM20702A
Bluetooth: hci1: BCM20702A1 (001.002.014) build 0000
bluetooth hci1: Direct firmware load for brcm/BCM20702A1-0b05-17cb.hcd failed with error -2
Bluetooth: hci1: BCM: Patch brcm/BCM20702A1-0b05-17cb.hcd not found

Luckily, the sys-firmware/broadcom-bt-firmware package can be used to install the most recent firmware files for Broadcom Bluetooth:

root #emerge --ask sys-firmware/broadcom-bt-firmware

After installation, reinsert Bluetooth device or reboot system for applying firmware. After the reboot the output should look something like the following:

user $dmesg | grep -i bluetooth

Bluetooth: hci1: BCM: chip id 63
Bluetooth: hci1: BCM20702A
Bluetooth: hci1: BCM20702A1 (001.002.014) build 0000
Bluetooth: hci1: BCM20702A1 (001.002.014) build 1467
Bluetooth: hci1: Broadcom Bluetooth Device

Configuration

After enabling the kernel options and installing firmware, proceed to the Bluetooth article.

Troubleshooting

Kernel requires BCM.hcd or BCM<CHIPSET>.hcd

Some VID/PIDs not yet defined in kernel driver so btbcm cannot properly identify the device:

user $dmesg | grep -i bluetooth

Bluetooth: hci1: BCM: chip id 63
Bluetooth: hci1: BCM20702A
Bluetooth: hci1: BCM20702A1 (001.002.014) build 0000
bluetooth hci1: Direct firmware load for brcm/BCM.hcd failed with error -2
Bluetooth: hci1: BCM: Patch brcm/BCM.hcd not found

In this case VID/PID will be manually retrieved via the lspci or lsusb commands:

user $lsusb

...
Bus 003 Device 005: ID 0b05:17cb ASUSTek Computer, Inc. Broadcom BCM20702A0 Bluetooth
...

Here the VID/PID - 0b05:17cb. Next, check the Devices list and choose firmware as appropriate. After that just copy firmware file into name that requires kernel:

root #cd /lib/firmware/brcm

root #cp BCM20702A1-0b05-17cb.hcd BCM.hcd

After that reinsert device or reboot system.

After installing firmware device still won't work

Some Bluetooth controller (for example, BCM4354 and BCM4356) are integrated to WiFi chipset (this can be BCM43XX 802.11ac Wireless Network Adapter or just simple generic Broadcom PCIE Wireless). These devices requires two kinds of firmware - first for WiFi, and second for Bluetooth. Without WiFi firmware Bluetooth will not initialize and will not work properly. Firmware for WiFi already included to kernel, but some additional work may be necessary to place correct NVRAM.

Here example how it can looks (note about brcm/brcmfmac4356-pcie.txt loading - this is the customized NVRAM):

user $dmesg

usbcore: registered new interface driver brcmfmac
brcmfmac 0000:02:00.0: firmware: direct-loading firmware brcm/brcmfmac4356-pcie.bin
brcmfmac 0000:02:00.0: firmware: direct-loading firmware brcm/brcmfmac4356-pcie.txt
Bluetooth: hci0: BCM: chip id 101
Bluetooth: hci0: N360-11
Bluetooth: hci0: BCM4354A2 (001.003.015) build 0000
bluetooth hci0: firmware: direct-loading firmware brcm/BCM4354A2-13d3-3485.hcd

See also

• Bluetooth — describes the configuration and usage of Bluetooth controllers and devices.