Hello, Sorry to butt in but I have some observations on this. I have been working on a related thing (https://github.com/Arkq/bluez-alsa) to add support for HFP and mSBC. HW: CSR8510 A10 dongle Jabra Halo Smart and LG HBS730 SW: Kernel: 4.4.0-53-generic #74-Ubuntu BlueZ 5.43 On Fri, Feb 10, 2017 at 3:48 AM, Marcel Holtmann <marcel@xxxxxxxxxxxx> wrote: > Hi Tanu, > >>>> PulseAudio recently started to use >>>> >>>> getsockopt(sock, SOL_SCO, SCO_OPTIONS, &sco_opt, &len); >>>> read_mtu = sco_opt.mtu; >>>> write_mtu = sco_opt.mtu; >>>> >>>> to query the MTU of the SCO socket. Previously we used a fixed value of >>>> 48, but that didn't work for some bluetooth chipsets (see the commit >>>> message[1]). Now, however, it was reported[2] that the new code doesn't >>>> work on some hardware where the old fixed MTU used to work. >>> >>> can you share details here and btmon traces for the data buffer sizes >>> and the USB descriptor details. We would need to figure out where >>> this goes wrong and maybe introduce some driver quirks to ensure that >>> it returns usable values. >> >> Georg already provided a btmon dump. Did that contain everything you >> need? The way you put your words, it's not clear to me if the USB >> descriptor details are included in the btmon output or is the USB >> descriptor a separate thing? >> >> I'd like to provide clear instructions for users to get the necessary >> information, in case it turns out that Georg is not the only one with >> this problem. What options should be given to btmon? > > < HCI Command: Read Local Version Info.. (0x04|0x0001) plen 0 >> HCI Event: Command Complete (0x0e) plen 12 > Read Local Version Information (0x04|0x0001) ncmd 1 > Status: Success (0x00) > HCI version: Bluetooth 2.0 (0x03) - Revision 5276 (0x149c) > LMP version: Bluetooth 2.0 (0x03) - Subversion 5276 (0x149c) > Manufacturer: Cambridge Silicon Radio (10) > < HCI Command: Read BD ADDR (0x04|0x0009) plen 0 >> HCI Event: Command Complete (0x0e) plen 10 > Read BD ADDR (0x04|0x0009) ncmd 1 > Status: Success (0x00) > Address: 00:15:83:73:FD:06 (IVT corporation) > < HCI Command: Read Buffer Size (0x04|0x0005) plen 0 >> HCI Event: Command Complete (0x0e) plen 11 > Read Buffer Size (0x04|0x0005) ncmd 1 > Status: Success (0x00) > ACL MTU: 384 ACL max packet: 8 > SCO MTU: 64 SCO max packet: 8 > > This seems to be CSR based hardware. Can we verify that this is the case with the /sys/kernel/debug/usb/devices info for this device. If this is a fake device, then all bets are off anyway. I am using this: T: Bus=02 Lev=02 Prnt=02 Port=03 Cnt=01 Dev#= 30 Spd=12 MxCh= 0 D: Ver= 2.00 Cls=e0(wlcon) Sub=01 Prot=01 MxPS=64 #Cfgs= 1 P: Vendor=0a12 ProdID=0001 Rev=88.91 S: Product=CSR8510 A10 C:* #Ifs= 2 Cfg#= 1 Atr=e0 MxPwr=100mA 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=1ms E: Ad=02(O) Atr=02(Bulk) MxPS= 64 Ivl=0ms 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 I: If#= 1 Alt= 1 #EPs= 2 Cls=e0(wlcon) Sub=01 Prot=01 Driver=btusb E: Ad=03(O) Atr=01(Isoc) MxPS= 9 Ivl=1ms E: Ad=83(I) 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=03(O) Atr=01(Isoc) MxPS= 17 Ivl=1ms E: Ad=83(I) 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=03(O) Atr=01(Isoc) MxPS= 25 Ivl=1ms E: Ad=83(I) 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=03(O) Atr=01(Isoc) MxPS= 33 Ivl=1ms E: Ad=83(I) 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=03(O) Atr=01(Isoc) MxPS= 49 Ivl=1ms E: Ad=83(I) Atr=01(Isoc) MxPS= 49 Ivl=1ms No idea if it is real or not though. I should have a Broadcom dongle around somewhere, I will see how it behaves. > > And yes, it reports 64 octets for the MTU. Which is most likely what you are getting back from the SCO socket. If this is all bogus and doesn’t work for CSR devices, we need to quirk it in the btusb driver to report a different value. What I am seeing is that the HCI device shows SCO MTU of 64 bytes, while the SCO connection request/response indicates a 60 byte payload size: hci0: Type: Primary Bus: USB BD Address: 00:1A:7D:DA:71:13 ACL MTU: 310:10 SCO MTU: 64:8 UP RUNNING PSCAN RX bytes:290561090 acl:5745 sco:6560504 events:7731 errors:0 TX bytes:63087159 acl:4785 sco:6783105 commands:1870 errors:2596 < HCI Command: Setup Synchronous Connection (0x01|0x0028) plen 17 [hci0] 31.193820 Handle: 69 Transmit bandwidth: 8000 Receive bandwidth: 8000 Max latency: 10 Setting: 0x0060 Input Coding: Linear Input Data Format: 2's complement Input Sample Size: 16-bit # of bits padding at MSB: 0 Air Coding Format: CVSD Retransmission effort: Optimize for power consumption (0x01) Packet type: 0x0380 3-EV3 may not be used 2-EV5 may not be used 3-EV5 may not be used > HCI Event: Command Status (0x0f) plen 4 [hci0] 31.196366 Setup Synchronous Connection (0x01|0x0028) ncmd 1 Status: Success (0x00) > HCI Event: Max Slots Change (0x1b) plen 3 [hci0] 31.203367 Handle: 69 Max slots: 1 > HCI Event: Synchronous Connect Complete (0x2c) plen 17 [hci0] 31.208364 Status: Success (0x00) Handle: 71 Address: 00:18:6B:52:A6:3F (Sambu Communics CO., LTD.) Link type: eSCO (0x02) Transmission interval: 0x0c Retransmission window: 0x02 RX packet length: 60 TX packet length: 60 Air mode: CVSD (0x02) .... However, for CVSD audio I also am getting 48 byte PDUs from the socket (btmon shows same size) but if I configure the SCO link in to transparent mode for mSBC I start getting 24 byte PDUs (again btmon shows 24 bytes as well). In both cases the bandwidth is the same 8000 kByte/s. > SCO Data RX: Handle 71 flags 0x00 dlen 48 [hci0] 31.234743 > SCO Data RX: Handle 71 flags 0x00 dlen 48 [hci0] 31.234744 In either case, if I actually send 60 or 64 byte PDUs, I hear nothing. As a workaround I am setting the write MTU based on the read MTU I get from the SCO socket and that seems reliable. (As a side note, I have not been able to make the mSBC output work, no headset of mine plays anything I send and I am pretty sure I have the framing correct. I will try another controller for this as well.) - Juha -- To unsubscribe from this list: send the line "unsubscribe linux-bluetooth" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
