[alsa-devel] [PATCH] ALSA: usb-audio: Disable quirks for BOSS Katana amplifiers

[Mike Oliphant]

When I tried this change earlier this year on the BOSS GT-1, it enabled
sound output on the card (which was not previously working), but with
significant issues. It resulted in frequent pops and crackles - presumably
because of the loss of synchronization using implicit feedback.

This was the fix that ended up working for me:

https://mailman.alsa-project.org/pipermail/alsa-devel/2020-January/161951.html

But maybe something else has changed in the handling of implicit feedback
since then?

Mike

On Wed, Oct 14, 2020 at 5:17 AM Mailing Lists <maillist at superlative.org>
wrote:

> Following up on this, it appears there are a bunch of the newer-generation
> Roland/Boss devices which need similar treatment.
>
> So far I have tested the GT-1, the GT-001, and the BR-80, and others have
> reported the RC-300 as working with similar modifications. I have been
> using the following change to the code in pcm.c
> set_sync_ep_implicit_fb_quirk:
>
>     case USB_ID(0x0582, 0x01d8): /* BOSS Katana */
>     case USB_ID(0x0582, 0x0130): /* BOSS Micro BR-80 */
>     case USB_ID(0x0582, 0x0138): /* BOSS RC-300 */
>     case USB_ID(0x0582, 0x01d6): /* BOSS GT-1 */
>     case USB_ID(0x0582, 0x01e5): /* BOSS GT-001 */
> /* BOSS Katana amplifiers and many other newer BOSS devices do not need
> quirks */
>
> There's probably others too, such as the GT-100 (I believe the GT-001 and
> GT-100 have similar hardware).
>
> My question is, should this just be submitted as a patch to pcm.c or would
> it be better handled in quirks and, if so, how?
>
> Or something else?
>
> Personally, I dislike the approach of hard-coding exceptions into core
> code as it seems that's what quirks are there for, but there seems to be a
> whole bunch of exceptions in there already.
>
> Cheers,
>
> Keith
>
> On Thu, 17 Oct 2019 at 09:20, Takashi Iwai <tiwai at suse.de> wrote:
>
>> On Fri, 11 Oct 2019 19:19:36 +0200,
>> Szabolcs Szőke wrote:
>> >
>> > BOSS Katana amplifiers cannot be used for recording or playback if
>> quirks
>> > are applied
>> >
>> > BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=195223
>> > Signed-off-by: Szabolcs Szőke <szszoke.code at gmail.com>
>>
>> Applied now.  Thanks.
>>
>>
>> Takashi
>>
>> >
>> > ---
>> >  sound/usb/pcm.c | 3 +++
>> >  1 file changed, 3 insertions(+)
>> >
>> > diff --git a/sound/usb/pcm.c b/sound/usb/pcm.c
>> > index 33cd26763c0e..daadb0c66eee 100644
>> > --- a/sound/usb/pcm.c
>> > +++ b/sound/usb/pcm.c
>> > @@ -348,6 +348,9 @@ static int set_sync_ep_implicit_fb_quirk(struct
>> snd_usb_substream *subs,
>> >               ep = 0x84;
>> >               ifnum = 0;
>> >               goto add_sync_ep_from_ifnum;
>> > +     case USB_ID(0x0582, 0x01d8): /* BOSS Katana */
>> > +             /* BOSS Katana amplifiers do not need quirks */
>> > +             return 0;
>> >       }
>> >
>> >       if (attr == USB_ENDPOINT_SYNC_ASYNC &&
>> > --
>> > 2.20.1
>> >
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>>
>
>
> --
> --
> Keith A Milner
>