Re: [alsa-devel] [PATCH] ALSA: usb-audio: Add quirk for Focusrite Scarlett 18i6

13 Nov 2012

At Fri, 9 Nov 2012 20:20:23 +1100,
Martin Schwenke wrote:
...
Probing this device currently fails in snd_usb_audio_probe() because
the call to snd_usb_create_mixer() fails.  This is due to unknown or
non-standard interface descriptor subtypes in parse_audio_unit():
usbaudio: unit 51: unexpected type 0x09
  snd-usb-audio: probe of 1-8:1.0 failed with error -5
Some people are working around this by recompiling usb-audio with the
call to snd_usb_create_mixer() commented out.  It would be nice to
avoid that.
While the best idea would be to look into the mixer creation failure,
a reasonable short-term solution is to use quirks to only probe the
trouble-free interfaces.  This allows audio and MIDI interfaces to be
used without any obvious issues.
Interface 0 is the main one to ignore.  It contains lots of
control-fu, including the unexpected interface descriptor subtypes.
Interface 5 is for firmware updates and I'm not sure how to get
support for this.  Interface 3 is some sort of control interface that
I don't understand:
Interface Descriptor:
  bLength                 9
  bDescriptorType         4
  bInterfaceNumber        3
  bAlternateSetting       0
  bNumEndpoints           0
  bInterfaceClass         1 Audio
  bInterfaceSubClass      1 Control Device
  bInterfaceProtocol      0
  iInterface              0
  AudioControl Interface Descriptor:
    bLength                 9
    bDescriptorType        36
    bDescriptorSubtype      1 (HEADER)
    bcdADC               1.00
    wTotalLength            9
    bInCollection           1
    baInterfaceNr( 0)       1


Signed-off-by: Martin Schwenke martin@meltin.net
Unfortunately your MUA broke lines so the patch cannot be applied
cleanly.  Please fix your MUA setup and resend, or use an attachment
if it doesn't work.
thanks,
Takashi
...

sound/usb/quirks-table.h |   52
++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 52
insertions(+)

diff --git a/sound/usb/quirks-table.h b/sound/usb/quirks-table.h
index 88d8ceb..c9dde5f 100644
--- a/sound/usb/quirks-table.h
+++ b/sound/usb/quirks-table.h
@@ -2882,6 +2882,58 @@ YAMAHA_DEVICE(0x7010, "UB99"),
{
   /*

* Focusrite Scarlett 18i6


*


* Avoid mixer creation, which otherwise fails because some of


* the interface descriptor subtypes for interface 0 are


* unknown.  That should be fixed or worked-around but this at


* least allows the device to be used successfully with a DAW


* and an external mixer.  See comments below about other


* ignored interfaces.


*/


USB_DEVICE(0x1235, 0x8004),
.driver_info = (unsigned long) & (const struct

snd_usb_audio_quirk) {

.vendor_name = "Focusrite",


.product_name = "Scarlett 18i6",


.ifnum = QUIRK_ANY_INTERFACE,


.type = QUIRK_COMPOSITE,


.data = & (const struct snd_usb_audio_quirk[]) {


	{


		/* InterfaceSubClass 1 (Control



Device) */

		.ifnum = 0,


		.type = QUIRK_IGNORE_INTERFACE


	},


	{


		.ifnum = 1,


		.type = QUIRK_AUDIO_STANDARD_INTERFACE


	},


	{


		.ifnum = 2,


		.type = QUIRK_AUDIO_STANDARD_INTERFACE


	},


	{


		/* InterfaceSubClass 1 (Control



Device) */

		.ifnum = 3,


		.type = QUIRK_IGNORE_INTERFACE


	},


	{


		.ifnum = 4,


		.type = QUIRK_MIDI_STANDARD_INTERFACE


	},


	{


		/* InterfaceSubClass 1 (Device



Firmware Update) */

		.ifnum = 5,


		.type = QUIRK_IGNORE_INTERFACE


	},


	{


		.ifnum = -1


	}


}


}

+},



+{

/*
Some USB MIDI devices don't have an audio control interface,
so we have to grab MIDI streaming interfaces here.

*/

-- 
1.7.10.4

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Re: [alsa-devel] [PATCH] ALSA: usb-audio: Add quirk for Focusrite Scarlett 18i6

Takashi Iwai