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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@quicinc.com> Acked-by: Mark Brown <broonie@kernel.org> Link: https://lore.kernel.org/r/20250409194804.3773260-31-quic_wcheng@quicinc.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
11 lines
304 B
C
11 lines
304 B
C
/* SPDX-License-Identifier: GPL-2.0
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*
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* Copyright (c) 2022-2025 Qualcomm Innovation Center, Inc. All rights reserved.
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*/
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#ifndef __USB_OFFLOAD_MIXER_H
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#define __USB_OFFLOAD_MIXER_H
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int snd_usb_offload_create_ctl(struct snd_usb_audio *chip, struct device *bedev);
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#endif /* __USB_OFFLOAD_MIXER_H */
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