Implicit feedback on BOSS GT-1, the saga continues...

[Mike Oliphant]

Geraldo - here is the dmesg output when starting up jackd for
capture/playback:

With my patch:

[  136.734081] usb 3-1.2: Open EP 0x8e, iface=2:1, idx=0
[  136.734088] usb 3-1.2:   channels=2, rate=44100, format=S32_LE,
period_bytes=256, periods=2, implicit_fb=0
[  136.734092] usb 3-1.2: Setting usb interface 2:0 for EP 0x8e
[  136.734233] usb 3-1.2: Setting usb interface 2:1 for EP 0x8e
[  136.734381] usb 3-1.2: 2:1 Set sample rate 44100, clock 0
[  136.734388] usb 3-1.2: Setting params for data EP 0x8e, pipe 0x70480
[  136.734394] usb 3-1.2: Set up 12 URBS, ret=0
[  136.734466] usb 3-1.2: Open EP 0xd, iface=1:1, idx=0
[  136.734468] usb 3-1.2:   channels=2, rate=44100, format=S32_LE,
period_bytes=256, periods=2, implicit_fb=1
[  136.734471] usb 3-1.2: Reopened EP 0x8e (count 1)
[  136.734473] usb 3-1.2: Setting usb interface 1:0 for EP 0xd
[  136.734605] usb 3-1.2: Setting usb interface 1:1 for EP 0xd
[  136.734762] usb 3-1.2: 1:1 Set sample rate 44100, clock 0
[  136.734774] usb 3-1.2: Setting params for data EP 0xd, pipe 0x68400
[  136.734781] usb 3-1.2: Set up 12 URBS, ret=0
[  136.734830] usb 3-1.2: Starting data EP 0xd (running 0)
[  136.734873] usb 3-1.2: 12 URBs submitted for EP 0xd
[  136.734876] usb 3-1.2: Starting data EP 0x8e (running 0)
[  136.734906] usb 3-1.2: 12 URBs submitted for EP 0x8e
[  136.740627] usb 3-1.2: Starting data EP 0x8e (running 1)
[  136.740634] usb 3-1.2: 2:1 Start Capture PCM
[  136.740635] usb 3-1.2: 1:1 Start Playback PCM


With the unpatched kernel:

[  344.813203] usb 3-1.2: Open EP 0x8e, iface=2:1, idx=0
[  344.813210] usb 3-1.2:   channels=2, rate=44100, format=S32_LE,
period_bytes=256, periods=2, implicit_fb=1
[  344.813213] usb 3-1.2: Open EP 0xd, iface=1:1, idx=0
[  344.813215] usb 3-1.2:   channels=2, rate=44100, format=S32_LE,
period_bytes=256, periods=2, implicit_fb=0
[  344.813217] usb 3-1.2: Setting usb interface 2:0 for EP 0x8e
[  344.813367] usb 3-1.2: Setting usb interface 2:1 for EP 0x8e
[  344.813494] usb 3-1.2: 2:1 Set sample rate 44100, clock 0
[  344.813503] usb 3-1.2: Setting params for data EP 0x8e, pipe 0x70580
[  344.813509] usb 3-1.2: Set up 12 URBS, ret=0
[  344.813513] usb 3-1.2: Setting usb interface 1:0 for EP 0xd
[  344.813587] usb 3-1.2: Setting usb interface 1:1 for EP 0xd
[  344.813758] usb 3-1.2: 1:1 Set sample rate 44100, clock 0
[  344.813765] usb 3-1.2: Setting params for data EP 0xd, pipe 0x68500
[  344.813770] usb 3-1.2: Set up 2 URBS, ret=0
[  344.813858] usb 3-1.2: Reopened EP 0xd (count 1)
[  344.813883] usb 3-1.2: Starting data EP 0xd (running 0)
[  344.813899] usb 3-1.2: 2 URBs submitted for EP 0xd
[  344.819499] usb 3-1.2: Starting data EP 0x8e (running 0)
[  344.819532] usb 3-1.2: 12 URBs submitted for EP 0x8e
[  344.819535] usb 3-1.2: Starting data EP 0xd (running 1)
[  344.819538] usb 3-1.2: 2:1 Start Capture PCM
[  344.819540] usb 3-1.2: 1:1 Start Playback PCM
[  344.820663] usb 3-1.2: Stopping data EP 0xd (running 2)
[  344.820688] usb 3-1.2: Stopping data EP 0x8e (running 1)
[  344.820693] usb 3-1.2: 2:1 Stop Capture PCM
[  344.820695] usb 3-1.2: Stopping data EP 0xd (running 1)
[  344.820697] usb 3-1.2: 1:1 Stop Playback PCM
[  344.833799] usb 3-1.2: Starting data EP 0xd (running 0)
[  344.833852] usb 3-1.2: 2 URBs submitted for EP 0xd
[  344.833867] usb 3-1.2: Starting data EP 0x8e (running 0)
[  344.833888] usb 3-1.2: 12 URBs submitted for EP 0x8e
[  344.833890] usb 3-1.2: Starting data EP 0xd (running 1)
[  344.833891] usb 3-1.2: 2:1 Start Capture PCM
[  344.833893] usb 3-1.2: 1:1 Start Playback PCM

On Wed, Apr 7, 2021 at 1:30 PM Geraldo Nascimento <geraldogabriel at gmail.com>
wrote:

> Em Qua, 7 de abr de 2021 17:16, Mike Oliphant <oliphant at nostatic.org>
> escreveu:
>
>> Hi Geraldo - I don't have that patch applied, but it shouldn't make any
>> behavioral difference - it just seems to be simplifying the code.
>>
>
> Point taken.
>
>
>> The issue is that the BOSS GT-1 *does* need implicit feedback on playback
>> to avoid clock timing issues, and the current behavior is disabling that
>> feedback.
>>
>
> Mike, would you mind posting some dyndbg logs for both the stock behaviour
> and your endpoint.c/generic quirk modified behaviour?
>
> Just add snd_usb_audio.dyndbg=+p to your kernel options and please share
> the logs.
>
>
>> Mike
>>
>> On Wed, Apr 7, 2021 at 1:04 PM Geraldo Nascimento <
>> geraldogabriel at gmail.com> wrote:
>>
>>> Hey Mike, did you catch the latest patch by Takashi Iwai for capture
>>> quirky devices?
>>>
>>> You can find it here:
>>> https://patchwork.kernel.org/project/alsa-devel/patch/20210406113837.32041-1-tiwai@suse.de/
>>>
>>> Em Qua, 7 de abr de 2021 16:55, Mike Oliphant <oliphant at nostatic.org>
>>> escreveu:
>>>
>>>> I had thought that the recent implicit feedback changes were fully
>>>> working
>>>> on the BOSS GT-1, but it turns out that I just hadn't tested well
>>>> enough.
>>>>
>>>> Audio playback and capture works, but with periodic dropouts. I get the
>>>> exact same behavior as I did with the quirk to completely disable
>>>> implicit
>>>> feedback. Without the implicit feedback, you get dropouts from clock
>>>> drift
>>>> - how bad probably varies from card to card. On mine it is every second
>>>> or
>>>> so.
>>>>
>>>> If I switch playback feedback for the GT-1 to generic by doing
>>>> "IMPLICIT_FB_GENERIC_DEV(0x0582, 0x01d6)", I get the previous old
>>>> behavior,
>>>> which is that playback completely fails to start.
>>>>
>>>> With generic playback feedback, and using my previous patch to
>>>> endpoint.c
>>>> to avoid playback waiting on capture mentioned here:
>>>>
>>>>
>>>> https://mailman.alsa-project.org/pipermail/alsa-devel/2020-January/161951.html
>>>>
>>>> playback and capture work perfectly for me.
>>>>
>>>