[PATCH] Bluetooth: btusb: Add USB ID 13d3:3556 for RTL8821CE

[PATCH] Bluetooth: btusb: Add USB ID 13d3:3556 for RTL8821CE

[Aritra Das]

The onboard Realtek RTL8821CE combo card on the ASUS PRIME B550-PLUS
AC-HES presents its Bluetooth function as USB ID 13d3:3556. This ID is
missing from quirks_table, so btusb matches the device only through the
generic Bluetooth class entry in btusb_table and driver_info stays zero.
BTUSB_REALTEK is therefore never set, btrtl never runs, and the
controller keeps executing its on-chip ROM firmware instead of loading
rtl_bt/rtl8821c_fw.bin and rtl_bt/rtl8821c_config.bin.

In that state BLE HID peripherals are unusable. A HHKB Hybrid keyboard
pairs and enumerates as a HID device, then the link drops within 10-30
seconds, repeatedly. The same keyboard is stable on the same host under
other operating systems.

Adding the ID lets btusb run the Realtek setup path:

  Bluetooth: hci0: RTL: examining hci_ver=08 hci_rev=000c lmp_ver=08 lmp_subver=8821
  Bluetooth: hci0: RTL: rom_version status=0 version=1
  Bluetooth: hci0: RTL: loading rtl_bt/rtl8821c_fw.bin
  Bluetooth: hci0: RTL: loading rtl_bt/rtl8821c_config.bin
  Bluetooth: hci0: RTL: cfg_sz 10, total sz 34926
  Bluetooth: hci0: RTL: fw version 0x75b8f098

With the firmware loaded the same keyboard has stayed connected for over
11 hours without a single drop.

Device descriptor:

T:  Bus=01 Lev=01 Prnt=01 Port=04 Cnt=02 Dev#=  2 Spd=12   MxCh= 0
D:  Ver= 1.10 Cls=e0(wlcon) Sub=01 Prot=01 MxPS=64 #Cfgs=  1
P:  Vendor=13d3 ProdID=3556 Rev=01.10
S:  Manufacturer=Realtek 
S:  Product=Bluetooth Radio 
S:  SerialNumber=00e04c000001
C:  #Ifs= 2 Cfg#= 1 Atr=e0 MxPwr=500mA
I:  If#= 0 Alt= 0 #EPs= 3 Cls=e0(wlcon) Sub=01 Prot=01 Driver=btusb
E:  Ad=02(O) Atr=02(Bulk) MxPS=  64 Ivl=0ms
E:  Ad=81(I) Atr=03(Int.) MxPS=  16 Ivl=1ms
E:  Ad=82(I) Atr=02(Bulk) MxPS=  64 Ivl=0ms
I:  If#= 1 Alt= 0 #EPs= 2 Cls=e0(wlcon) Sub=01 Prot=01 Driver=btusb
E:  Ad=03(O) Atr=01(Isoc) MxPS=   0 Ivl=1ms
E:  Ad=83(I) Atr=01(Isoc) MxPS=   0 Ivl=1ms

Signed-off-by: Aritra Das <aritra.rohit2003@gmail.com>
---
 drivers/bluetooth/btusb.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/bluetooth/btusb.c b/drivers/bluetooth/btusb.c
index 03039ce..0424898 100644
--- a/drivers/bluetooth/btusb.c
+++ b/drivers/bluetooth/btusb.c
@@ -511,6 +511,8 @@ static const struct usb_device_id quirks_table[] = {
 						     BTUSB_WIDEBAND_SPEECH },
 	{ USB_DEVICE(0x13d3, 0x3533), .driver_info = BTUSB_REALTEK |
 						     BTUSB_WIDEBAND_SPEECH },
+	{ USB_DEVICE(0x13d3, 0x3556), .driver_info = BTUSB_REALTEK |
+						     BTUSB_WIDEBAND_SPEECH },
 	{ USB_DEVICE(0x13d3, 0x3558), .driver_info = BTUSB_REALTEK |
 						     BTUSB_WIDEBAND_SPEECH },
 
base-commit: 6696072ffe07205255cf83621a95a1aa2f9f6e62

Re: [PATCH] Bluetooth: btusb: Add USB ID 13d3:3556 for RTL8821CE

[patchwork-bot+bluetooth]

Hello:

This patch was applied to bluetooth/bluetooth-next.git (master)
by Luiz Augusto von Dentz <luiz.von.dentz@intel.com>:

On Thu,  3 Sep 2026 10:03:22 -0700 you wrote:
> The onboard Realtek RTL8821CE combo card on the ASUS PRIME B550-PLUS
> AC-HES presents its Bluetooth function as USB ID 13d3:3556. This ID is
> missing from quirks_table, so btusb matches the device only through the
> generic Bluetooth class entry in btusb_table and driver_info stays zero.
> BTUSB_REALTEK is therefore never set, btrtl never runs, and the
> controller keeps executing its on-chip ROM firmware instead of loading
> rtl_bt/rtl8821c_fw.bin and rtl_bt/rtl8821c_config.bin.
> 
> [...]

Here is the summary with links:
  - Bluetooth: btusb: Add USB ID 13d3:3556 for RTL8821CE
    https://git.kernel.org/bluetooth/bluetooth-next/c/88a6bc5607e2

You are awesome, thank you!
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