Allow for checks on a specific USB audio device to see if a requested PCM format is supported. This is needed for support when playback is initiated by the ASoC USB backend path.
Signed-off-by: Wesley Cheng quic_wcheng@quicinc.com --- sound/usb/card.c | 40 ++++++++++++++++++++++++++++++++++++++++ sound/usb/card.h | 11 +++++++++++ 2 files changed, 51 insertions(+)
diff --git a/sound/usb/card.c b/sound/usb/card.c index c0b312e264bf..11b827b7a2a5 100644 --- a/sound/usb/card.c +++ b/sound/usb/card.c @@ -162,6 +162,46 @@ int snd_usb_unregister_platform_ops(void) } EXPORT_SYMBOL_GPL(snd_usb_unregister_platform_ops);
+/* + * Checks to see if requested audio profile, i.e sample rate, # of + * channels, etc... is supported by the substream associated to the + * USB audio device. + */ +struct snd_usb_stream *snd_usb_find_suppported_substream(int card_idx, + struct snd_pcm_hw_params *params, int direction) +{ + struct snd_usb_audio *chip; + struct snd_usb_substream *subs; + struct snd_usb_stream *as; + const struct audioformat *fmt; + + /* + * Register mutex is held when populating and clearing usb_chip + * array. + */ + mutex_lock(®ister_mutex); + chip = usb_chip[card_idx]; + if (!chip) { + mutex_unlock(®ister_mutex); + return NULL; + } + + if (enable[card_idx]) { + list_for_each_entry(as, &chip->pcm_list, list) { + subs = &as->substream[direction]; + fmt = snd_usb_find_substream_format(subs, params); + if (fmt) { + mutex_unlock(®ister_mutex); + return as; + } + } + } + mutex_unlock(®ister_mutex); + + return NULL; +} +EXPORT_SYMBOL_GPL(snd_usb_find_suppported_substream); + /* * disconnect streams * called from usb_audio_disconnect() diff --git a/sound/usb/card.h b/sound/usb/card.h index 02e4ea898db5..ed4a664e24e5 100644 --- a/sound/usb/card.h +++ b/sound/usb/card.h @@ -217,4 +217,15 @@ struct snd_usb_platform_ops {
int snd_usb_register_platform_ops(struct snd_usb_platform_ops *ops); int snd_usb_unregister_platform_ops(void); + +#if IS_ENABLED(CONFIG_SND_USB_AUDIO) +struct snd_usb_stream *snd_usb_find_suppported_substream(int card_idx, + struct snd_pcm_hw_params *params, int direction); +#else +static struct snd_usb_stream *snd_usb_find_suppported_substream(int card_idx, + struct snd_pcm_hw_params *params, int direction) +{ + return NULL; +} +#endif /* IS_ENABLED(CONFIG_SND_USB_AUDIO) */ #endif /* __USBAUDIO_CARD_H */