On Wed, 06 Nov 2024 20:34:11 +0100, Wesley Cheng wrote: > > In order to allow userspace/applications know about USB offloading status, > expose a sound kcontrol that fetches information about which sound card > and PCM index the USB device is mapped to for supporting offloading. In > the USB audio offloading framework, the ASoC BE DAI link is the entity > responsible for registering to the SOC USB layer. > > It is expected for the USB SND offloading driver to add the kcontrol to the > sound card associated with the USB audio device. An example output would > look like: > > tinymix -D 1 get 'USB Offload Playback Route PCM#0' > -1, -1 (range -1->255) > > This example signifies that there is no mapped ASoC path available for the > USB SND device. > > tinymix -D 1 get 'USB Offload Playback Route PCM#0' > 0, 0 (range -1->255) > > This example signifies that the offload path is available over ASoC sound > card index#0 and PCM device#0. > > The USB offload kcontrol will be added in addition to the existing > kcontrols identified by the USB SND mixer. The kcontrols used to modify > the USB audio device specific parameters are still valid and expected to be > used. These parameters are not mirrored to the ASoC subsystem. > > Signed-off-by: Wesley Cheng <quic_wcheng@xxxxxxxxxxx> IIRC, this representation of kcontrol was one argued issue; Pierre expressed the concern about the complexity of the kcontrol. I didn't follow exactly, but did we get consensus? Apart from that: the Kconfig defition below ... > +config SND_USB_OFFLOAD_MIXER > + tristate "USB Audio Offload mixer control" > + help > + Say Y to enable the USB audio offloading mixer controls. This > + exposes an USB offload capable kcontrol to signal to applications > + about which platform sound card can support USB audio offload. > + The returning values specify the mapped ASoC card and PCM device > + the USB audio device is associated to. ... and Makefile addition below ... > --- a/sound/usb/Makefile > +++ b/sound/usb/Makefile > @@ -36,3 +36,5 @@ obj-$(CONFIG_SND_USB_US122L) += snd-usbmidi-lib.o > > obj-$(CONFIG_SND) += misc/ usx2y/ caiaq/ 6fire/ hiface/ bcd2000/ qcom/ > obj-$(CONFIG_SND_USB_LINE6) += line6/ > + > +obj-$(CONFIG_SND_USB_OFFLOAD_MIXER) += mixer_usb_offload.o ... indicates that this code will be an individual module, although it's solely used from snd-usb-audio-qmi driver. This should be rather a boolean and moved to sound/usb/qcom/, and linked to snd-usb-audio-qmi driver itself, e.g. --- a/sound/usb/qcom/Makefile +++ b/sound/usb/qcom/Makefile @@ -1,2 +1,3 @@ snd-usb-audio-qmi-objs := usb_audio_qmi_v01.o qc_audio_offload.o +snd-usb-audio-qmi-$(CONFIG_SND_USB_OFFLOAD_MIXER) += mixer_usb_offload.o obj-$(CONFIG_SND_USB_AUDIO_QMI) += snd-usb-audio-qmi.o Then you can drop EXPORT_SYMBOL_GPL(), too. thanks, Takashi
