Re: Raspberry Pi 3 / BCM43438 + HSP profile + PulseAudio

["Attila Tőkés" <attitokes@gmail.com>]

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Hi Marcel,

I just sent a patch with the changes for the SCO routing:
[PATCH] Bluetooth: hci_bcm: Configure SCO routing automatically

The patch applies to the bluetooth-next branch. I tested it with a 4.15.18
kernel (rpi build).

Thanks,
Attila

On Sun, Jan 21, 2018 at 9:22 PM, Attila Tőkés <attitokes@gmail.com> wrote:

> Hi Marcel,
>
>
> On Sun, Jan 21, 2018 at 2:21 PM, Marcel Holtmann <marcel@holtmann.org>
> wrote:
> > Hi Tokes,
> >
> >>>>>> I'm trying to use a Bluetooth speaker with Raspberry Pi 3 in HSP
> mode
> >>>>>> with PulseAudio.
> >>>>>>
> >>>>>> Based on the information I found on the web (blogs / forums /
> mailing
> >>>>>> list archives), apparently, HSP does not really works with the
> >>>>>> Rasberry Pi's built in BCM43438 chip. I didn't found the exact
> reason
> >>>>>> yet. Some people suggest it may be a problem with the BCM43438
> >>>>>> firmware or with the kernel driver. A2DP, and HSP with USB Bluetooth
> >>>>>> dongles are reported to be working fine. (The most complete
> >>>>>> description I found about the problem is:
> >>>>>> http://youness.net/raspberry-pi/bluetooth-headset-
> raspberry-pi-3-ad2p-hsp)
> >>>>>>
> >>>>>> I think it would be useful to get clear picture about the problem.
> And
> >>>>>> maybe we could try to fix it.
> >>>>>>
> >>>>>> Does anyone managed to figure out what exactly the problem is?
> >>>>>>
> >>>>>> I started investigating the issue, but didn't got any result yet. I
> >>>>>> didn't had too much experience with the Linux's Bluetooth stack, so
> >>>>>> some help with the further investigation would be useful.
> >>>>>>
> >>>>>> ----
> >>>>>>
> >>>>>> Bellow are some details of my investigation.
> >>>>>>
> >>>>>> Hardware: Raspberry Pi 3 + JBL GO! Bluetooth speaker
> >>>>>>
> >>>>>> Kernel: raspberrypi 4.14.14-v7
> >>>>>> BlueZ: 5.43
> >>>>>> PulseAudio: 11.1
> >>>>>>
> >>>>>> Summary:
> >>>>>> - BCM43438's driver is sucessfuly loaded, it's firmware is uploaded
> successfully
> >>>>>> - the Bluetooth speaker gets detected and the pairing / connection
> works fine
> >>>>>> - PulseAudio detects the speaker as a card
> >>>>>> - both the headset_head_unit and a2dp_sink profiles are shown by
> >>>>>> `pacmd list-cards` and can be set with `pacmd set-card-profile`
> >>>>>> - with the a2dp_sink profile, the audio playback works fine (tested
> >>>>>> with `paplay`)
> >>>>>> - with the headset_head_unit profile, `paplay` gets stuck at start a
> >>>>>> no audio is played (`parecord` does the same)
> >>>>>>
> >>>>>> I started booth BlueZ and PulseAudio in debug mode, but found
> nothing
> >>>>>> obviuosly wrong (at least for me :P) in the logs. Also did a HCI
> dump.
> >>>>>>
> >>>>>> Linking the following logs (uploaded to PasteBin; they are too long
> >>>>>> inline them):
> >>>>>> - the Blootoothd's log - https://pastebin.com/WC17Ze0r
> >>>>>> - the PlulseAudio's log - https://pastebin.com/jUjqjuhC
> >>>>>> - the output of the PA commands - https://pastebin.com/wvRzdTEx
> >>>>>> - the output of some BL Tools (sdptool / bluetoothctl / hciconfig) -
> >>>>>> https://pastebin.com/Ax7XYr94
> >>>>>> - the HCI dump -https://pastebin.com/zqhqKu57
> >>>>>>
> >>>>>> SCO dump did not managed to get.
> >>>>>>
> >>>>>> I executed the following steps:
> >>>>>> (the steps are marked in the log files too):
> >>>>>> - start Blootoothd
> >>>>>> - start PulseAudio
> >>>>>> - powered on the Bloothooth speaker
> >>>>>> - tried to play some audio
> >>>>>> $ pacmd list cards
> >>>>>> $ pacmd set-card-profile 1 headset_head_unit
> >>>>>> $ paplay -v -d bluez_sink.78_44_05_4B_4F_FF.headset_head_unit
> >>>>>> /tmp/h2g2.ogg (gets stuck)
> >>>>>> $ pacmd set-card-profile 1 a2dp_sink
> >>>>>> $ paplay -v -d bluez_sink.78_44_05_4B_4F_FF.a2dp_sink
> /tmp/h2g2.ogg (works)
> >>>>>
> >>>>> HSP playback getting stuck is a fairly common problem (affecting
> >>>>> multiple bluetooth adapters from different vendors). Solutions for
> the
> >>>>> problem are known for a few adapters, but not this one. The issue is
> >>>>> documented here (the "HSP problem: the bluetooth sink and source are
> >>>>> created, but no audio is being transmitted" section):
> >>>>>
> >>>>> https://www.freedesktop.org/wiki/Software/PulseAudio/
> Documentation/User/Bluetooth/#index8h3
> >>>>>
> >>>>> As you can read there, the underlying problem in the known cases is
> >>>>> either that firmware is missing or the SCO audio routing is wrong in
> >>>>> the adapter. Changing the routing requires (at least in the known
> >>>>> cases) a vendor-specific magic command. I don't know how to figure
> out
> >>>>> the correct command. On one Broadcom chip this does the trick:
> "hcitool
> >>>>> cmd 0x3F 0x01C 0x01 0x02 0x00 0x01 0x01", but I don't know how likely
> >>>>> that is to work on a different chip.
> >>>>
> >>>> I just sent that HCI command right now and guess what, it worked :).
> >>>> Both paplay an parecord are working fine with the HSP profile now.
> >>>
> >>> Awesome! I'll update the wiki page.
> >>
> >> Ok, Thanks! I posted the solution to the two related GitHub issues +
> >> some forums / blog posts, so hope it will reach anyone interested in
> >> this.
> >
> > I would be more interested in someone adding this kind of PCM routing
> configuration to DT and also adopting the hci_bcm.c driver to use it and
> send the appropriate commands.
>
> I could take a look on adding the new functionality to hci_bcm.c. I'm
> not really familiar with the Linux kernel development, so be aware
> that this will take some time.
>
> >
> > Sending hcitool cmd is like injecting commands. That is a hack. It is
> not a solution. So commenting that you need some hcitool to hack the
> hardware setup, that is just wrong. Get this merged into the driver and
> have it configurable via DT.
>
> Yes, I know its not the best solution, but it fixes the problem and
> this is more important for most of the people, than having the "right"
> solution. That's why I posted it to GitHub, etc.
>
> >
> > Also if you have a recent enough btmon installed, then it might actually
> decode the Broadcom commands for you. Can you give it a try and see what it
> says.
> >
>
> Actually, I found a document today with the vendor specific HCI
> commands for the Cypress CYW4329/CYW4330 chip
> (http://www.cypress.com/file/298311/download). Its not the same chip,
> by I guess the commands will be similar for all the Cypress / Broadcom
> chips.
>
> According to this document the HCI command
> hcitool cmd 0x3F 0x01C 0x01 0x02 0x00 0x01 0x01
>
> translates to:
>
> command = 0x01C (Write_SCO_PCM_Int_Param)
>    SCO_Routing = 0x01 (Transport)
>    PCM_Interface_Rate = 0x02 (512 KBps)
>    Frame_Type = 0x00 (Short)
>    Sync_Mode = 0x01 (Master)
>    Clock_Mode = 0x01 (Master)
>
> btmon (5.43) does not seems to know to decode the command. It outputs this:
>
> $ sudo btmon -s /org/bluez/hci0
> ...
> @ RAW Open: hcitool (privileged) version 2.22            {0x0003} 16.534966
> @ RAW Close: hcitool
> {0x0003} 16.534997
> @ RAW Open: hcitool (privileged) version 2.22            {0x0003}
> [hci0] 16.535043
> < HCI Command: Vendor (0x3f|0x001c) plen 5             [hci0] 16.535162
>         01 02 00 01 01                                   .....
> > HCI Event: Command Complete (0x0e) plen 4          [hci0] 16.535566
>       Vendor (0x3f|0x001c) ncmd 1
>         Status: Success (0x00)
> @ RAW Close: hcitool
>
> > Regards
> >
> > Marcel
> >
>
> Thanks,
> Attila
>

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