+static struct snd_soc_dai_driver q6usb_be_dais[] = { + { + .playback = { + .stream_name = "USB BE RX", + .rates = SNDRV_PCM_RATE_8000 | SNDRV_PCM_RATE_11025 | + SNDRV_PCM_RATE_16000 | SNDRV_PCM_RATE_22050 | + SNDRV_PCM_RATE_32000 | SNDRV_PCM_RATE_44100 | + SNDRV_PCM_RATE_48000 | SNDRV_PCM_RATE_96000 | + SNDRV_PCM_RATE_192000, + .formats = SNDRV_PCM_FMTBIT_S16_LE | SNDRV_PCM_FMTBIT_S16_BE | + SNDRV_PCM_FMTBIT_U16_LE | SNDRV_PCM_FMTBIT_U16_BE | + SNDRV_PCM_FMTBIT_S24_LE | SNDRV_PCM_FMTBIT_S24_BE | + SNDRV_PCM_FMTBIT_U24_LE | SNDRV_PCM_FMTBIT_U24_BE, + .channels_min = 1, + .channels_max = 2, + .rate_max = 192000, + .rate_min = 8000, + }, + .id = USB_RX, + .name = "USB_RX_BE", + .ops = &q6usb_ops, + }, +};
... here I see a single DAI, so presumably ONE endpoint can be supported?
One USB audio device can be supported. one AFE port = one USB audio device
I didn't see in the rest of the code how a card with multiple endpoint would be rejected, nor how the capabilities are checked?
Need to take a look at this query a bit more. Let me try to pass in a format that can't be supported by the audio DSP, and see if the formats specified in this structure will not allow userspace to start the session.
When you say a "card with multiple endpoints" are you referring to a USB device that exposes multiple data (ISOC let's say) eps for its data interface? I haven't run into a device like that.
A headset will typically only have two isoc endpoints for playback and capture respectively, but while that's a very large market USB audio is far from restricted to this configuration. It's not uncommon for the pro or prosumer market to see devices with multiple input/output capabilities and run-time mixing on the host.