Hi Takashi,
On 2/9/2024 2:42 AM, Takashi Iwai wrote:
On Fri, 09 Feb 2024 00:13:45 +0100,
Wesley Cheng wrote:
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@xxxxxxxxxxx>
---
sound/usb/card.c | 31 +++++++++++++++++++++++++++++++
sound/usb/card.h | 11 +++++++++++
2 files changed, 42 insertions(+)
diff --git a/sound/usb/card.c b/sound/usb/card.c
index 7dc8007ba839..1ad99a462038 100644
--- a/sound/usb/card.c
+++ b/sound/usb/card.c
@@ -155,6 +155,37 @@ 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;
+
+ /*
+ * Register mutex is held when populating and clearing usb_chip
+ * array.
+ */
+ guard(mutex)(®ister_mutex);
+ chip = usb_chip[card_idx];
+
+ if (chip && enable[card_idx]) {
+ list_for_each_entry(as, &chip->pcm_list, list) {
+ subs = &as->substream[direction];
+ if (snd_usb_find_substream_format(subs, params))
+ return as;
+ }
+ }
+
+ 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) */
The usefulness of ifdef guard here is doubtful, IMO. This header is
only for USB-audio driver enablement, and not seen as generic
helpers. So, just add the new function declarations without dummy
definitions.
Got it, will remove it. We also have a dependency in place for the
qc_audio_offload driver and SND USB AUDIO in the Kconfig.
Thanks
Wesley Cheng
