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

[Takashi Iwai]

On Wed, 14 Oct 2020 15:56:32 +0200,
Mailing Lists wrote:
> 
> Yes, and I don't think this is practical (at least, not obviously).
> 
> The "Roland" vs "BOSS" thing is pure branding. I have BOSS branded devices,
> like the JS-8, which work perfectly without the patch as an example. It
> wouldn't surprise me if there are recent Roland branded devices which require
> the patch.
> 
> So I, personally, think it is beyond brand and is device range or generation
> specific. I guess it is possible there may be some technical parameter within
> the device descriptor which could indicate which variant the device is, but I
> don't know what that might be (if at all). At this point I think we probably
> have to apply a conditional setting based on the Product ID.
> 
> Given that, is it best to continue hacking these into pcm.c, or should we be
> looking at a quirks-table way to describe these?

Currently it's better to grow the explicit allow-list, I suppose.
Those are still handful, hence manageable enough.

But, we should consider improving search_roland_implicit_fb(), too.
Both actions don't conflict, and once after we establish the better
implicit-fb check, the allow-list can be dropped.


thanks,

Takashi

> 
> Cheers,
> 
> Keith
> 
> On Wed, 14 Oct 2020 at 14:47, Takashi Iwai <tiwai at suse.de> wrote:
> 
>     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 at 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
>     >
>     >
> 
> --
> --
> Keith A Milner
> 
>