[Alsa-user] S32_LE Missing for Hardware

[Ed S. <ed...@lo...>]

I have a sound card with a CM6631A audio chip running UAC 2.0. 

There are 2 analogue sub devices on the chip both of which should support S32_LE, however I do not see the S32_LE alt setting for one of the outputs.

lsusb -v, I see the following for each output:

  Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        1
      bAlternateSetting       3
      bNumEndpoints           2
      bInterfaceClass         1 Audio
      bInterfaceSubClass      2 Streaming
      bInterfaceProtocol     32 
      iInterface              0 
      AudioStreaming Interface Descriptor:
        bLength                16
        bDescriptorType        36
        bDescriptorSubtype      1 (AS_GENERAL)
        bTerminalLink           1
        bmControls           0x05
          Active Alternate Setting Control (read-only)
          Valid Alternate Setting Control (read-only)
        bFormatType             1
        bmFormats         0x00000001
          PCM
        bNrChannels             2
        bmChannelConfig   0x00000003
          Front Left (FL)
          Front Right (FR)
        iChannelNames           0 
      AudioStreaming Interface Descriptor:
        bLength                 6
        bDescriptorType        36
        bDescriptorSubtype      2 (FORMAT_TYPE)
        bFormatType             1 (FORMAT_TYPE_I)
        bSubslotSize            4
        bBitResolution         32


and 

Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        3
      bAlternateSetting       3
      bNumEndpoints           2
      bInterfaceClass         1 Audio
      bInterfaceSubClass      2 Streaming
      bInterfaceProtocol     32 
      iInterface              0 
      AudioStreaming Interface Descriptor:
        bLength                16
        bDescriptorType        36
        bDescriptorSubtype      1 (AS_GENERAL)
        bTerminalLink           3
        bmControls           0x05
          Active Alternate Setting Control (read-only)
          Valid Alternate Setting Control (read-only)
        bFormatType             1
        bmFormats         0x00000001
          PCM
        bNrChannels             2
        bmChannelConfig   0x00000003
          Front Left (FL)
          Front Right (FR)
        iChannelNames           0 
      AudioStreaming Interface Descriptor:
        bLength                 6
        bDescriptorType        36
        bDescriptorSubtype      2 (FORMAT_TYPE)
        bFormatType             1 (FORMAT_TYPE_I)
        bSubslotSize            4
        bBitResolution         32

Both of the above have an entry for bit resolution of 32 for bAlternateSetting 3. 

Output of alsa-capabilities

 0) USB Audio Class Digital alsa audio output interface `hw:0,0'
 - device name       = USB2.0 High-Speed True HD Audio                             
 - interface name    = USB Audio                                                   
 - usb audio class   = 2 - isochronous asynchronous                                
 - character device  = /dev/snd/pcmC0D0p                                           
 - encoding formats  = S24_3LE, S16_LE                                             
 - monitor file      = /proc/asound/card0/pcm0p/sub0/hw_params                     
 - stream file       = /proc/asound/card0/stream0                                  

 1) USB Audio Class Digital alsa audio output interface `hw:0,1'
 - device name       = USB2.0 High-Speed True HD Audio                             
 - interface name    = USB Audio #1                                                
 - usb audio class   = 2 - isochronous asynchronous                                
 - character device  = /dev/snd/pcmC0D1p                                           
 - encoding formats  = S24_3LE, S32_LE, S16_LE                                     
 - monitor file      = /proc/asound/card0/pcm1p/sub0/hw_params                     
 - stream file       = /proc/asound/card0/stream1    

Sub device 0 is missing the S32_LE alt setting.

When I plug this into OSX, I see 32bit support on both outputs.

uname -a
Linux ubuntu 4.4.0-72-lowlatency #93-Ubuntu SMP PREEMPT Fri Mar 31 15:25:21 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux

cat /proc/asound/version 
Advanced Linux Sound Architecture Driver Version k4.4.0-72-lowlatency.
(reporting v1.1.0 in alsamixer)


Any guidance is appreciated.

Ed Stark