Commit 2bde4392 authored by Wesley Cheng's avatar Wesley Cheng Committed by Greg Kroah-Hartman
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ALSA: usb-audio: Check for support for requested audio format 



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.

Reviewed-by: default avatarPierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: default avatarWesley Cheng <quic_wcheng@quicinc.com>
Acked-by: default avatarMark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20250409194804.3773260-10-quic_wcheng@quicinc.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 5a49a6ba

sound/usb/card.c

+32 −0
Original line number Diff line number Diff line
@@ -119,6 +119,38 @@ static DEFINE_MUTEX(register_mutex); 
static struct snd_usb_audio *usb_chip[SNDRV_CARDS];

static struct usb_driver usb_audio_driver;



/*

 * 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)(&register_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()

sound/usb/card.h

+3 −0
Original line number Diff line number Diff line
@@ -207,4 +207,7 @@ struct snd_usb_stream { 
	struct list_head list;

};



struct snd_usb_stream *

snd_usb_find_suppported_substream(int card_idx, struct snd_pcm_hw_params *params,

				  int direction);

#endif /* __USBAUDIO_CARD_H */