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Message-ID: <ad851c66-5c5f-4bbb-b278-7b0c49b3cb07@linux.intel.com>
Date: Tue, 17 Oct 2023 17:29:05 -0500
From: Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
To: Wesley Cheng <quic_wcheng@...cinc.com>, mathias.nyman@...el.com,
gregkh@...uxfoundation.org, lgirdwood@...il.com,
broonie@...nel.org, perex@...ex.cz, tiwai@...e.com,
agross@...nel.org, andersson@...nel.org, konrad.dybcio@...aro.org,
robh+dt@...nel.org, krzysztof.kozlowski+dt@...aro.org,
conor+dt@...nel.org, srinivas.kandagatla@...aro.org,
bgoswami@...cinc.com, Thinh.Nguyen@...opsys.com
Cc: linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
alsa-devel@...a-project.org, linux-arm-msm@...r.kernel.org,
devicetree@...r.kernel.org
Subject: Re: [PATCH v9 20/34] ALSA: usb-audio: Check for support for requested
audio format
On 10/17/23 15:00, 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 for when playback is
This is needed for support when playback is
> initiated by the ASoC USB backend path.
>
> Signed-off-by: Wesley Cheng <quic_wcheng@...cinc.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..88f431917c15 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 = NULL;
useless init?
> + 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 2884912adc96..e26292363cf0 100644
> --- a/sound/usb/card.h
> +++ b/sound/usb/card.h
> @@ -216,4 +216,15 @@ 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 */
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