Implicit feedback on BOSS GT-1, the saga continues...
Geraldo Nascimento
geraldogabriel at gmail.com
Fri Apr 9 03:04:41 CEST 2021
Em Qui, 8 de abr de 2021 19:02, Mike Oliphant <oliphant at nostatic.org>
escreveu:
> Geraldo - not sure what your patch was intended to do, but it results in
> the same behavior.
>
Mike, sorry I thought it was obvious that the patch prevented pcm.c from
accidentally picking up the implicit feedback EP as sync EP. That cropped
up in your early 2020 post
https://mailman.alsa-project.org/pipermail/alsa-devel/2020-January/161733.html
so I thought it was worth a shot.
Mainly I'm sorry I start to believe you when you say these Roland / BOSS
devices may be quirky enough to actually need some kind of kickstart
workaround.
But I warn you it won't be easy-peasy to get this patch accepted, and so...
the saga continues...
With implicit feedback enabled for playback but without the endpoint.c
> patch, playback fails to initialize. I'm including the dmesg log below. The
> key message is the "No URB submission due to implicit fb sync" line, which
> is what the endpoint.c patch avoids.
>
The only way to be 100% sure is to see what the Windows or Mac working
driver does. Now I'm not suggesting you do some reverse engineering to
prove beyond all doubts that your case for one more new quirk system inside
ALSA is needed.
But I'm suggesting you submit your patch to the maintainer obviously not
using the generic implicit feedback static entry to a device that has
already another entry that specifies implicit feedback in the other
direction.
That will only create even more confusion. You said my patch works for you
if you modify endpoint.c. Are you sure you get crystal clear sound from my
patch plus your endpoint.c patch?
Mike
>
> -- device plugged in
>
> [ 1066.587414] usb 4-1.2: new high-speed USB device number 12 using
> ehci-pci
> [ 1066.697993] usb 4-1.2: New USB device found, idVendor=0582,
> idProduct=01d6, bcdDevice= 0.00
> [ 1066.698013] usb 4-1.2: New USB device strings: Mfr=1, Product=2,
> SerialNumber=0
> [ 1066.698020] usb 4-1.2: Product: GT-1
> [ 1066.698024] usb 4-1.2: Manufacturer: BOSS
> [ 1066.701638] usb 4-1.2: 1:1: added playback implicit_fb sync_ep 8e,
> iface 2:1
> [ 1066.701655] usb 4-1.2: 1:1: add audio endpoint 0xd
> [ 1066.701680] usb 4-1.2: Creating new data endpoint #d
> [ 1066.701682] usb 4-1.2: Creating new data endpoint #8e
> [ 1066.701828] usb 4-1.2: 1:1 Set sample rate 44100, clock 0
> [ 1066.702337] usb 4-1.2: 2:1: add audio endpoint 0x8e
> [ 1066.702522] usb 4-1.2: 2:1 Set sample rate 44100, clock 0
>
> -- jackd started for capture/playback
>
> [ 1072.455008] usb 4-1.2: Open EP 0x8e, iface=2:1, idx=0
> [ 1072.455016] usb 4-1.2: channels=2, rate=44100, format=S32_LE,
> period_bytes=256, periods=2, implicit_fb=0
> [ 1072.455020] usb 4-1.2: Setting usb interface 2:0 for EP 0x8e
> [ 1072.455096] usb 4-1.2: Setting usb interface 2:1 for EP 0x8e
> [ 1072.455286] usb 4-1.2: 2:1 Set sample rate 44100, clock 0
> [ 1072.455296] usb 4-1.2: Setting params for data EP 0x8e, pipe 0x70c80
> [ 1072.455316] usb 4-1.2: Set up 12 URBS, ret=0
> [ 1072.455418] usb 4-1.2: Open EP 0xd, iface=1:1, idx=0
> [ 1072.455421] usb 4-1.2: channels=2, rate=44100, format=S32_LE,
> period_bytes=256, periods=2, implicit_fb=1
> [ 1072.455425] usb 4-1.2: Reopened EP 0x8e (count 1)
> [ 1072.455442] usb 4-1.2: Setting usb interface 1:0 for EP 0xd
> [ 1072.455633] usb 4-1.2: Setting usb interface 1:1 for EP 0xd
> [ 1072.455741] usb 4-1.2: 1:1 Set sample rate 44100, clock 0
> [ 1072.455747] usb 4-1.2: Setting params for data EP 0xd, pipe 0x68c00
> [ 1072.455754] usb 4-1.2: Set up 12 URBS, ret=0
> [ 1072.455784] usb 4-1.2: Starting data EP 0xd (running 0)
> [ 1072.455788] usb 4-1.2: No URB submission due to implicit fb sync
> [ 1072.455790] usb 4-1.2: Starting data EP 0x8e (running 0)
> [ 1072.455828] usb 4-1.2: 12 URBs submitted for EP 0x8e
> [ 1072.461297] usb 4-1.2: Starting data EP 0x8e (running 1)
> [ 1072.461313] usb 4-1.2: 2:1 Start Capture PCM
> [ 1072.461316] usb 4-1.2: 1:1 Start Playback PCM
> [ 1073.549291] usb 4-1.2: Stopping data EP 0x8e (running 2)
> [ 1073.549297] usb 4-1.2: 2:1 Stop Capture PCM
> [ 1073.549300] usb 4-1.2: Stopping data EP 0x8e (running 1)
> [ 1073.549307] usb 4-1.2: Stopping data EP 0xd (running 1)
> [ 1073.549309] usb 4-1.2: 1:1 Stop Playback PCM
> [ 1073.581795] usb 4-1.2: Closing EP 0x8e (count 2)
> [ 1073.581814] usb 4-1.2: Closing EP 0xd (count 1)
> [ 1073.581816] usb 4-1.2: Setting usb interface 1:0 for EP 0xd
> [ 1073.582098] usb 4-1.2: EP 0xd closed
> [ 1073.582102] usb 4-1.2: Closing EP 0x8e (count 1)
> [ 1073.582104] usb 4-1.2: Setting usb interface 2:0 for EP 0x8e
> [ 1073.582331] usb 4-1.2: EP 0x8e closed
>
> -- jackd fails to start
>
> On Thu, Apr 8, 2021 at 2:28 PM Geraldo Nascimento <
> geraldogabriel at gmail.com> wrote:
>
>> Mike, could you test the following patch instead of your own
>> modifications?
>>
>> Lucas, you can test it too, just modify it for your devices.
>>
>> Since I don't own any Roland devices this is of course completely
>> untested, but it's worth a try.
>>
>> --- implicit.c.git 2021-04-04 20:51:57.226754632 -0300
>> +++ implicit.c 2021-04-08 18:15:02.971301050 -0300
>> @@ -75,7 +75,7 @@ static const struct snd_usb_implicit_fb_
>> IMPLICIT_FB_SKIP_DEV(0x0582, 0x0171), /* BOSS RC-505 */
>> IMPLICIT_FB_SKIP_DEV(0x0582, 0x0185), /* BOSS GP-10 */
>> IMPLICIT_FB_SKIP_DEV(0x0582, 0x0189), /* BOSS GT-100v2 */
>> - IMPLICIT_FB_SKIP_DEV(0x0582, 0x01d6), /* BOSS GT-1 */
>> + //IMPLICIT_FB_SKIP_DEV(0x0582, 0x01d6), /* BOSS GT-1 */
>> IMPLICIT_FB_SKIP_DEV(0x0582, 0x01d8), /* BOSS Katana */
>> IMPLICIT_FB_SKIP_DEV(0x0582, 0x01e5), /* BOSS GT-001 */
>> IMPLICIT_FB_SKIP_DEV(0x0582, 0x0203), /* BOSS AD-10 */
>> @@ -89,7 +89,7 @@ static const struct snd_usb_implicit_fb_
>> IMPLICIT_FB_FIXED_DEV(0x0582, 0x0171, 0x0d, 0x01), /* BOSS RC-505
>> */
>> IMPLICIT_FB_FIXED_DEV(0x0582, 0x0185, 0x0d, 0x01), /* BOSS GP-10
>> */
>> IMPLICIT_FB_FIXED_DEV(0x0582, 0x0189, 0x0d, 0x01), /* BOSS
>> GT-100v2 */
>> - IMPLICIT_FB_FIXED_DEV(0x0582, 0x01d6, 0x0d, 0x01), /* BOSS GT-1 */
>> + //IMPLICIT_FB_FIXED_DEV(0x0582, 0x01d6, 0x0d, 0x01), /* BOSS GT-1
>> */
>> IMPLICIT_FB_FIXED_DEV(0x0582, 0x01d8, 0x0d, 0x01), /* BOSS Katana
>> */
>> IMPLICIT_FB_FIXED_DEV(0x0582, 0x01e5, 0x0d, 0x01), /* BOSS GT-001
>> */
>> IMPLICIT_FB_FIXED_DEV(0x0582, 0x0203, 0x0d, 0x01), /* BOSS AD-10
>> */
>> @@ -339,8 +339,19 @@ int snd_usb_parse_implicit_fb_quirk(stru
>> struct audioformat *fmt,
>> struct usb_host_interface *alts)
>> {
>> - if (fmt->endpoint & USB_DIR_IN)
>> + bool isRolandGT1;
>> +
>> + if (alts->desc.bInterfaceClass == USB_CLASS_VENDOR_SPEC &&
>> + (USB_ID_VENDOR(chip->usb_id) == 0x0582 &&
>> + USB_ID_PRODUCT(chip->usb_id) == 0x01d6 /* BOSS GT-1 */))
>> + isRolandGT1 = true;
>> +
>> + if (fmt->endpoint & USB_DIR_IN) {
>> + if (isRolandGT1 == true)
>> + return 1;
>> return audioformat_capture_quirk(chip, fmt, alts);
>> + }
>> +
>> else
>> return audioformat_implicit_fb_quirk(chip, fmt, alts);
>> }
>>
>> On Thu, Apr 8, 2021 at 5:54 PM Mike Oliphant <oliphant at nostatic.org>
>> wrote:
>>
>>> Geraldo - the implicit feedback stuff is by no means new - it's been
>>> there for quite some time. The recent changes just refactored it a bit.
>>>
>>> Mike
>>>
>>> On Thu, Apr 8, 2021 at 1:09 PM Geraldo Nascimento <
>>> geraldogabriel at gmail.com> wrote:
>>>
>>>> Em Qui, 8 de abr de 2021 16:42, Mike Oliphant <oliphant at nostatic.org>
>>>> escreveu:
>>>>
>>>>> Hi Geraldo - yes. In fact, that is how I've been operating for the
>>>>> past year or so before the recent implicit feedback changes. I use the GT-1
>>>>> most every day as a guitar interface and it works perfectly.
>>>>>
>>>>
>>>> Thanks Mike, but I'm not sure I understand. You have been operating
>>>> with implicit feedback sync on the playback for the past year? I thought
>>>> that was a new idea?
>>>>
>>>> The key point here is that with a stock kernel you have to comment out
>>>> the IMPLICIT_FB_SKIP_DEV() entry for the GT-1 for the Roland code inside
>>>> audioformat_implicit_fb_quirk properly kick in.
>>>>
>>>> I was suggesting you try your workaround without adding a
>>>> IMPLICIT_FB_GENERIC_DEV() for your device.
>>>>
>>>>
>>>>> The GT-1 (and I suspect many of the other Roland/BOSS devices) doesn't
>>>>> seem to be quirky at all with regard to implicit feedback setup - it works
>>>>> exactly as the endpoint definitions say it should.
>>>>>
>>>>> Where the GT-1 *does* seem to be quirky is that is doesn't seem to
>>>>> want to send capture data until it receives some playback data - hence my
>>>>> endpoint.c patch.
>>>>>
>>>>
>>>> If that is true then there's definitely a need to rewrite endpoint.c.
>>>> But it could be something else, Mike. One thing is certain: the present
>>>> kernel behaviour is far from the ideal.
>>>>
>>>> I insist: engage implicit feedback sync for the playback, disable it
>>>> for the captures and inspect your dyndbg logs for the failure cases in
>>>> starting JACK that happen when you don't patch endpoint.c.
>>>>
>>>> If you see something related to sync_ep then the problem lies
>>>> elsewhere, specifically inside pcm.c
>>>>
>>>> Although whether this behavior is quirky or typical I don't know. I do
>>>>> know that the GT-1 does not claim to be USB class compliant. It requires
>>>>> custom drivers on Windows and macOS and does not work at all with iOS, so
>>>>> it definitely seems to be somewhat non-standard.
>>>>>
>>>>
>>>> Non-standard to say the least. I really hope that's not the case or
>>>> it'll give Takashi Iwai plenty of headache ;-)
>>>>
>>>>
>>>>> Mike
>>>>>
>>>>> On Thu, Apr 8, 2021 at 12:13 PM Geraldo Nascimento <
>>>>> geraldogabriel at gmail.com> wrote:
>>>>>
>>>>>> Hey Mike, got another question for you, sorry about that.
>>>>>>
>>>>>> If you comment out your GT-1 IMPLICIT_FB_GENERIC_DEV() entry and
>>>>>> instead let audioformat_implicit_fb_quirk() call add_roland_implicit_fb()
>>>>>> with everything else customized your way, your custom endpoint.c etc., does
>>>>>> it still work? And does it work crystal clear?
>>>>>>
>>>>>> I'm sorry about this test this, test that, provide the dyndbg logs
>>>>>> attitude but I'm honestly just trying to help you write the best patch
>>>>>> possible.
>>>>>>
>>>>>> Thank you,
>>>>>> Geraldo
>>>>>>
>>>>>> Em Qui, 8 de abr de 2021 02:05, Geraldo Nascimento <
>>>>>> geraldogabriel at gmail.com> escreveu:
>>>>>>
>>>>>>> Mike, I just realize I missed reply-to-all once again.
>>>>>>>
>>>>>>> In case you were wondering, I was looking for a sync_ep event right
>>>>>>> in the start of the loading of snd-usb-audio. It happens inside pcm.c. If
>>>>>>> you see one of those specifically let me know.
>>>>>>>
>>>>>>> With my Pioneer device, the DDJ-SR2, snd-usb-audio recognized the
>>>>>>> device's implicit feedback EP as sync_ep and that prevented JACK from
>>>>>>> starting.
>>>>>>>
>>>>>>> Em Qua, 7 de abr de 2021 23:47, Mike Oliphant <oliphant at nostatic.org>
>>>>>>>> escreveu:
>>>>>>>>
>>>>>>>>> Hi Geraldo - I had the same thought and I have tried enabling
>>>>>>>>> playback feedback while turning off capture feedback without my endpoint
>>>>>>>>> patch. It doesn't work - at least not on the GT-1. Playback/capture fails
>>>>>>>>> to start.
>>>>>>>>>
>>>>>>>>
>>>>>>>> Would you mind sharing the dyndbg logs for the failure case from
>>>>>>>> the point you connect the device, and trying to start JACK?
>>>>>>>>
>>>>>>>> Sometimes failures elucidate more than success cases.
>>>>>>>>
>>>>>>>>
>>>>>>>>> Speaking of testing, if you (or anyone else following this
>>>>>>>>> discussion) have one of these Roland/BOSS devices, it would be great if you
>>>>>>>>> could try testing with playback feedback enabled and my endpoint.c
>>>>>>>>> workaround.
>>>>>>>>>
>>>>>>>>
>>>>>>>> I don't have the hardware, but I'm sure it works. The problem is
>>>>>>>> that endpoint.c code really shouldn't be disabled unless all the other
>>>>>>>> options fail, and even then, I'm not so sure the maintainers will be so
>>>>>>>> willing to disable it. So let's keep some other options on the table by
>>>>>>>> debugging a little further.
>>>>>>>>
>>>>>>>> Thank you,
>>>>>>>> Geraldo
>>>>>>>>
>>>>>>>>
>>>>>>>>> Mike
>>>>>>>>>
>>>>>>>>> On Wed, Apr 7, 2021 at 7:21 PM Geraldo Nascimento <
>>>>>>>>> geraldogabriel at gmail.com> wrote:
>>>>>>>>>
>>>>>>>>>> Thanks, Mike, one thing I can tell you right off the bat is that
>>>>>>>>>> if you turn implicit feedback sync on for both endpoints at the same time
>>>>>>>>>> like you mentioned, without your workaround inside endpoint.c, they most
>>>>>>>>>> likely will stall because they would both be waiting for each other to
>>>>>>>>>> start.
>>>>>>>>>>
>>>>>>>>>> Have you tried engaging the generic implicit feedback sync just
>>>>>>>>>> for the playback, thereby commenting out the capture implicit feedback
>>>>>>>>>> entries, and re-enabling snd_usb_endpoint_implicit_feedback_sink(ep) inside
>>>>>>>>>> endpoint.c? Does playback still fail to start?
>>>>>>>>>>
>>>>>>>>>> If you choose to perform this simple test please share with us
>>>>>>>>>> the test's dyndbg logs right from the moment you turn on the device, not
>>>>>>>>>> just after you start jackd.
>>>>>>>>>>
>>>>>>>>>> Sorry for the endless do-this, do-that. Such is the pace of
>>>>>>>>>> teledebugging
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> Em Qua, 7 de abr de 2021 21:38, Mike Oliphant <
>>>>>>>>>> oliphant at nostatic.org> escreveu:
>>>>>>>>>>
>>>>>>>>>>> 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.
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
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