On Thu, Feb 08, 2024 at 03:45:05PM +0100, Mariusz Białończyk wrote: > Hi, > I am trying to use an RFCOMM-capable dongle under Arch Linux (kernel: 6.6.10-arch1-1). > The BT usb adapter is: > ID 0bda:8771 Realtek Semiconductor Corp. Bluetooth Radio > > dmesg: > [ 19.174428] Bluetooth: Core ver 2.22 > [ 19.174448] NET: Registered PF_BLUETOOTH protocol family > [ 19.174448] Bluetooth: HCI device and connection manager initialized > [ 19.174452] Bluetooth: HCI socket layer initialized > [ 19.174454] Bluetooth: L2CAP socket layer initialized > [ 19.174460] Bluetooth: SCO socket layer initialized > [ 20.497753] Bluetooth: hci0: RTL: examining hci_ver=0a hci_rev=000b lmp_ver=0a lmp_subver=8761 > [ 20.500891] Bluetooth: hci0: RTL: rom_version status=0 version=1 > [ 20.500894] Bluetooth: hci0: RTL: loading rtl_bt/rtl8761bu_fw.bin > [ 20.502433] Bluetooth: hci0: RTL: loading rtl_bt/rtl8761bu_config.bin > [ 20.503140] Bluetooth: hci0: RTL: cfg_sz 6, total sz 30210 > [ 20.898620] Bluetooth: BNEP (Ethernet Emulation) ver 1.3 > [ 20.898620] Bluetooth: BNEP filters: protocol multicast > [ 20.898620] Bluetooth: BNEP socket layer initialized > [ 21.285074] Bluetooth: hci0: RTL: fw version 0xdfc6d922 > [ 21.430191] Bluetooth: MGMT ver 1.22 > [ 40.360736] Bluetooth: RFCOMM TTY layer initialized > [ 40.360743] Bluetooth: RFCOMM socket layer initialized > [ 40.360746] Bluetooth: RFCOMM ver 1.11 > > The rfcomm utility was not provided so I had to install: > https://archlinux.org/packages/extra/x86_64/bluez-deprecated-tools/ > > unfortunately the command: > rfcomm connect 0 B8:8B:15:0A:1C:AD > gives: > Can't connect RFCOMM socket: Operation now in progress > > I tried also with bind - all of this gives errors. > Finally I tried python tools to directly use RFCOMM, then even a rust > rfcat tool from: > https://github.com/bluez/bluer/blob/master/bluer-tools/src/rfcat.rs > All gives various errors/timeouts and cannot connect to the dongle's > serial port. I was also trying to pair/connect with bluetoothctl prior > this - no change. > In fact (see below - pairing seems not needed at all). > > Finally I started very very old Asus laptop with debian. > I invoked: > rfcomm connect 0 B8:8B:15:0A:1C:AD > and this immediately gives me: > Connected /dev/rfcomm0 to B8:8B:15:0A:1C:AD on channel 1 > Press CTRL-C for hangup > > ... and it works like a charm!!! I can connect minicom and communication is > working (no pairing/connecting with bluetoothctl needed). > > dmesg there: > [ 298.641307] Bluetooth: Core ver 2.22 > [ 298.641393] Bluetooth: HCI device and connection manager initialized > [ 298.641405] Bluetooth: HCI socket layer initialized > [ 298.641409] Bluetooth: L2CAP socket layer initialized > [ 298.641419] Bluetooth: SCO socket layer initialized > [ 299.673331] Bluetooth: hci0: unexpected event for opcode 0x0000 > [ 311.510413] Bluetooth: BNEP (Ethernet Emulation) ver 1.3 > [ 311.510422] Bluetooth: BNEP filters: protocol multicast > [ 311.510435] Bluetooth: BNEP socket layer initialized > [ 1902.017008] Bluetooth: RFCOMM TTY layer initialized > [ 1902.017026] Bluetooth: RFCOMM socket layer initialized > [ 1902.017048] Bluetooth: RFCOMM ver 1.11 > > the adapter is: > ID 0b05:1712 ASUSTek Computer, Inc. BT-183 Bluetooth 2.0+EDR adapter > > I am now trying to identify the problem. I've logged all data using > btmon from the start to invoking the rfcom connect. > > I can see that the difference start when my Asus laptop is showing this: > < ACL Data TX: Handle 42 flags 0x02 dlen 10 #13 [hci0] 40.891571 > L2CAP: Information Request (0x0a) ident 1 len 2 > Type: Extended features supported (0x0002) > > HCI Event: Number of Completed Packets (0x13) plen 5 #14 [hci0] 40.898476 > Num handles: 1 > Handle: 42 Address: B8:8B:15:0A:1C:AD (OUI B8-8B-15) > Count: 1 > > ACL Data RX: Handle 42 flags 0x02 dlen 16 #15 [hci0] 40.899488 > L2CAP: Information Response (0x0b) ident 1 len 8 > Type: Extended features supported (0x0002) > Result: Success (0x0000) > Features: 0x00000000 > < ACL Data TX: Handle 42 flags 0x02 dlen 12 #16 [hci0] 40.899554 > L2CAP: Connection Request (0x02) ident 2 len 4 > PSM: 3 (0x0003) > Source CID: 64 > > I don't see any L2CAP and RFCOMM lines on the "bad" ArchLinux setup. > > Please help! I really like to connect to this dongle (even no matter > which software involved - I just want to access this serialport somehow). > > I am attaching full logs (called good and bad). dvbsnoop logs also > included. > > ps. I tested the dongle also from Windows and Android - also works OK. some new info on this problem: I've exposed the laptop's bluetooth adapter to my ArchLinux using USB/IP method. This way on the same platform where the Realtek USB adapter is not working I was able to also use laptop's BT adapter. Here are the results: ❯ rfcomm -i hci1 connect 0 B8:8B:15:0A:1C:AD Connected /dev/rfcomm0 to B8:8B:15:0A:1C:AD on channel 1 Press CTRL-C for hangup ^CDisconnected # works great ❯ rfcomm -i hci0 connect 0 B8:8B:15:0A:1C:AD Can't connect RFCOMM socket: Operation now in progress Conclusion: the ArchLinux platform is OK (i mean the distribution, bluetooth stack, kernel modules and utilities). The problem seems the buggy Realtek drivers/firmware for my rtl8761bu ? Guys please take a look at the logs ... if you confirm than maybe some bug report would be needed ... I am also CC-ing Ziqian SUN (Zamir), who added RTL8761B support into the kernel, so maybe he can take a look into this issue... I am not attaching the logs again, original message with attachments is available in the bluetooth ML, and also eg here: https://www.spinics.net/lists/linux-bluetooth/msg109274.html -- regards, Mariusz Białończyk https://skyboo.net | https://github.com/manio
