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

[Takashi Iwai <tiwai@suse.de>]

On Wed, 14 Oct 2020 15:33:03 +0200,
Mailing Lists wrote:
> 
> Thanks for the response Takashi,
> 
> How should this be distinguishing between Roland and BOSS? They both have the
> vendor ID 0x0582.

Ah, right, I missed that point :-<

So the question would be rather how to detect BOSS devices
effectively...


thanks,

Takashi

> 
> Cheers,
> 
> Keith
> 
> On Wed, 14 Oct 2020 at 14:09, Takashi Iwai <tiwai@suse.de> wrote:
> 
>     On Wed, 14 Oct 2020 14:17:35 +0200,
>     Mailing Lists 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?
>    
>     Do we really need this change at all?  I looked at the code again, and
>     I noticed that basically the function should return 0 without setting
>     anything else even if you don't have the explicit ID checks there.
>    
>     The function looks like:
>    
>     static int set_sync_ep_implicit_fb_quirk(struct snd_usb_substream *subs,
>                                              struct usb_device *dev,
>                                              struct usb_interface_descriptor
>     *altsd,
>                                              unsigned int attr)
>     {
>             ....
>             switch (subs->stream->chip->usb_id) {
>             ....
>             case USB_ID(0x0582, 0x01d8): /* BOSS Katana */
>                     /* BOSS Katana amplifiers do not need quirks */
>                     return 0;
>             }
>    
>             if (attr == USB_ENDPOINT_SYNC_ASYNC &&
>                 altsd->bInterfaceClass == USB_CLASS_VENDOR_SPEC &&
>                 altsd->bInterfaceProtocol == 2 &&
>                 altsd->bNumEndpoints == 1 &&
>                 USB_ID_VENDOR(subs->stream->chip->usb_id) == 0x0582 /* Roland
>     */ &&
>                 search_roland_implicit_fb(dev, altsd->bInterfaceNumber + 1,
>                                           altsd->bAlternateSetting,
>                                           &alts, &ep) >= 0) {
>                     goto add_sync_ep;
>             }
>    
>             /* No quirk */
>             return 0;
>    
>     ... and the lengthy if-conditions after the switch/case is applied
>     only for Roland devices, hence it shouldn't influence on BOSS
>     devices.  After that point, the immediate return with 0, which is the
>     same as we do in switch/case.  So the explicit check of BOSS devices
>     there looks superfluous.
> 
>     thanks,
>    
>     Takashi
> 
> --
> --
> Keith A Milner
> 
>