In case of notifying SND platform drivers of connection events, some of these use cases, such as offloading, require an ASoC USB backend device to be initialized before the events can be handled. If the USB backend device has not yet been probed, this leads to missing initial USB audio device connection events.
Expose an API that traverses the usb_chip array for connected devices, and to call the respective connection callback registered to the SND platform driver.
Signed-off-by: Wesley Cheng quic_wcheng@quicinc.com --- sound/usb/card.c | 19 +++++++++++++++++++ sound/usb/card.h | 2 ++ 2 files changed, 21 insertions(+)
diff --git a/sound/usb/card.c b/sound/usb/card.c index e51461ac33cd..25267c1cc64e 100644 --- a/sound/usb/card.c +++ b/sound/usb/card.c @@ -170,6 +170,25 @@ struct snd_usb_stream *snd_usb_find_suppported_substream(int card_idx, } EXPORT_SYMBOL_GPL(snd_usb_find_suppported_substream);
+/* + * in case the platform driver was not ready at the time of USB SND + * device connect, expose an API to discover all connected USB devices + * so it can populate any dependent resources/structures. + */ +void snd_usb_rediscover_devices(void) +{ + int i; + + mutex_lock(®ister_mutex); + for (i = 0; i < SNDRV_CARDS; i++) { + if (usb_chip[i]) + if (platform_ops && platform_ops->connect_cb) + platform_ops->connect_cb(usb_chip[i]); + } + mutex_unlock(®ister_mutex); +} +EXPORT_SYMBOL_GPL(snd_usb_rediscover_devices); + /* * disconnect streams * called from usb_audio_disconnect() diff --git a/sound/usb/card.h b/sound/usb/card.h index 922868d2dccd..7bbaee87a48a 100644 --- a/sound/usb/card.h +++ b/sound/usb/card.h @@ -219,6 +219,7 @@ int snd_usb_register_platform_ops(struct snd_usb_platform_ops *ops); int snd_usb_unregister_platform_ops(void); struct snd_usb_stream *snd_usb_find_suppported_substream(int card_idx, struct snd_pcm_hw_params *params, int direction); +void snd_usb_rediscover_devices(void); #else int snd_usb_register_platform_ops(struct snd_usb_platform_ops *ops) { @@ -235,5 +236,6 @@ struct snd_usb_stream *snd_usb_find_suppported_substream(int card_idx, { return NULL; } +void snd_usb_rediscover_devices(void) { } #endif /* IS_ENABLED(CONFIG_SND_USB_AUDIO) */ #endif /* __USBAUDIO_CARD_H */