[alsa-devel] aplay -l vs. aplay -L: Missing PCMs?

[Stephen Warren]

The Azalia controller on NVIDIA GPUs gives 4 ALSA hw devices:

(on card 1):

[swarren at swarren-lx2 ~]$ sudo aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: NVidia [HDA NVidia], device 0: ALC1200 Analog [ALC1200 Analog]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 0: NVidia [HDA NVidia], device 3: ALC1200 Digital [ALC1200 Digital]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 1: NVidia_1 [HDA NVidia], device 3: NVIDIA HDMI [NVIDIA HDMI]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 1: NVidia_1 [HDA NVidia], device 7: NVIDIA HDMI [NVIDIA HDMI]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 1: NVidia_1 [HDA NVidia], device 8: NVIDIA HDMI [NVIDIA HDMI]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 1: NVidia_1 [HDA NVidia], device 9: NVIDIA HDMI [NVIDIA HDMI]
  Subdevices: 1/1
  Subdevice #0: subdevice #0

... all of which appear to work OK.

However, the list of available "PCMs" from aplay -L doesn't expose them all:

[swarren at swarren-lx2 ~]$ sudo aplay -L
front:CARD=NVidia,DEV=0
    HDA NVidia, ALC1200 Analog
    Front speakers
surround40:CARD=NVidia,DEV=0
    HDA NVidia, ALC1200 Analog
    4.0 Surround output to Front and Rear speakers
surround41:CARD=NVidia,DEV=0
    HDA NVidia, ALC1200 Analog
    4.1 Surround output to Front, Rear and Subwoofer speakers
surround50:CARD=NVidia,DEV=0
    HDA NVidia, ALC1200 Analog
    5.0 Surround output to Front, Center and Rear speakers
surround51:CARD=NVidia,DEV=0
    HDA NVidia, ALC1200 Analog
    5.1 Surround output to Front, Center, Rear and Subwoofer speakers
surround71:CARD=NVidia,DEV=0
    HDA NVidia, ALC1200 Analog
    7.1 Surround output to Front, Center, Side, Rear and Woofer speakers
hdmi:CARD=NVidia,DEV=0
    HDA NVidia, ALC1200 Digital
    HDMI Audio Output
null
    Discard all samples (playback) or generate zero samples (capture)
pulse
    Playback/recording through the PulseAudio sound server
hdmi:CARD=NVidia_1
    HDA NVidia, NVIDIA HDMI
    HDMI Audio Output

Similarly, pulseaudio only shows one output for the GPU; I assume it uses
the same enumeration mechanism for ALSA sinks as "aplay -L".

Instead, I imagined that I'd see 4 PCMs listed by "aplay -L"; one for each
converter. Is this an incorrect assumption? How would I make that happen?

I imagine that's why Google shows up so many hits on probe_mask for NVIDIA
GPUs, so that the one that does show up is the one users want?

Thanks.

-- 
nvpublic