@@ -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()
@@ -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 */
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(+)