[alsa-devel] Roland V-Studio 20

[Keith A. Milner]

I've recently picked up a cheap Roland V-Studio 20 device. This is described 
in the product spec as supporting 24-bit, but it is appearing as 16-bit only.

Unfortunately, Roland seem to insist on their own proprietary descriptors, 
which I don't know how to decode, so I'm not sure whether this is genuinely a 
24-bit interface that isn't being interpreted properly by snd-usb-audio, or 
whether it's marketing spin, and it's actually 16-bit.

I know that some patches were put into snd-usb-audio to "unify" some of the 
individual quirks that were used for Roland gear, but I don;t know if these 
support 24-bit interfaces.

Any ideas/suggestions?

The lsusb -v is as follows:

Bus 007 Device 002: ID 0582:0117 Roland Corp. 
Device Descriptor:
  bLength                18
  bDescriptorType         1
  bcdUSB               1.10
  bDeviceClass          255 Vendor Specific Class
  bDeviceSubClass         0 
  bDeviceProtocol       255 
  bMaxPacketSize0         8
  idVendor           0x0582 Roland Corp.
  idProduct          0x0117 
  bcdDevice            1.00
  iManufacturer           1 Cakewalk
  iProduct                2 VS-20
  iSerial                 0 
  bNumConfigurations      1
  Configuration Descriptor:
    bLength                 9
    bDescriptorType         2
    wTotalLength          167
    bNumInterfaces          3
    bConfigurationValue     1
    iConfiguration          0 
    bmAttributes         0x80
      (Bus Powered)
    MaxPower              360mA
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        0
      bAlternateSetting       0
      bNumEndpoints           0
      bInterfaceClass       255 Vendor Specific Class
      bInterfaceSubClass      2 
      bInterfaceProtocol      2 
      iInterface              0 
      ** UNRECOGNIZED:  06 24 f1 01 00 00
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        0
      bAlternateSetting       1
      bNumEndpoints           1
      bInterfaceClass       255 Vendor Specific Class
      bInterfaceSubClass      2 
      bInterfaceProtocol      2 
      iInterface              0 
      ** UNRECOGNIZED:  07 24 01 01 00 01 00
      ** UNRECOGNIZED:  0b 24 02 01 02 03 18 01 44 ac 00
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x01  EP 1 OUT
        bmAttributes            9
          Transfer Type            Isochronous
          Synch Type               Adaptive
          Usage Type               Data
        wMaxPacketSize     0x0120  1x 288 bytes
        bInterval               1
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        1
      bAlternateSetting       0
      bNumEndpoints           0
      bInterfaceClass       255 Vendor Specific Class
      bInterfaceSubClass      2 
      bInterfaceProtocol      1 
      iInterface              0 
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        1
      bAlternateSetting       1
      bNumEndpoints           1
      bInterfaceClass       255 Vendor Specific Class
      bInterfaceSubClass      2 
      bInterfaceProtocol      1 
      iInterface              0 
      ** UNRECOGNIZED:  07 24 01 07 00 01 00
      ** UNRECOGNIZED:  0b 24 02 01 02 03 18 01 44 ac 00
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x82  EP 2 IN
        bmAttributes            5
          Transfer Type            Isochronous
          Synch Type               Asynchronous
          Usage Type               Data
        wMaxPacketSize     0x0120  1x 288 bytes
        bInterval               1
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        2
      bAlternateSetting       0
      bNumEndpoints           2
      bInterfaceClass       255 Vendor Specific Class
      bInterfaceSubClass      3 
      bInterfaceProtocol      0 
      iInterface              0 
      ** UNRECOGNIZED:  06 24 f1 02 02 02
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x03  EP 3 OUT
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0020  1x 32 bytes
        bInterval               0
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x84  EP 4 IN
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0020  1x 32 bytes
        bInterval               0
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        2
      bAlternateSetting       1
      bNumEndpoints           2
      bInterfaceClass       255 Vendor Specific Class
      bInterfaceSubClass      3 
      bInterfaceProtocol      0 
      iInterface              0 
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x03  EP 3 OUT
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0020  1x 32 bytes
        bInterval               0
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x84  EP 4 IN
        bmAttributes            3
          Transfer Type            Interrupt
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0020  1x 32 bytes
        bInterval               1
Device Status:     0x0000
  (Bus Powered)