2024-05-07 19:59:48

by Wesley Cheng

Subject: [PATCH v21 33/39] ASoC: usb: Fetch ASoC sound card information

For USB sound to expose mixer controls to fetch information about the ASoC
sound card, add an API that returns the platform sound card number that is
registered with SOC USB. Knowing this allows for applications to further
query about the offload status.

Signed-off-by: Wesley Cheng <[email protected]>
---
include/sound/soc-usb.h | 6 ++++++
sound/soc/soc-usb.c | 20 ++++++++++++++++++++
2 files changed, 26 insertions(+)

diff --git a/include/sound/soc-usb.h b/include/sound/soc-usb.h
index cdf5a4e34789..9e1789efbb3d 100644
--- a/include/sound/soc-usb.h
+++ b/include/sound/soc-usb.h
@@ -85,6 +85,7 @@ int snd_soc_usb_find_supported_format(int card_idx,
int snd_soc_usb_connect(struct device *usbdev, struct snd_soc_usb_device *sdev);
int snd_soc_usb_disconnect(struct device *usbdev, struct snd_soc_usb_device *sdev);
void *snd_soc_usb_find_priv_data(struct device *dev);
+int snd_soc_usb_device_offload_available(struct device *dev);

int snd_soc_usb_prepare_session(struct snd_soc_usb *usb, int card_idx, int pcm_idx);
int snd_soc_usb_shutdown_session(struct snd_soc_usb *usb, int session_id);
@@ -129,6 +130,11 @@ static inline void *snd_soc_usb_find_priv_data(struct device *dev)
return NULL;
}

+static inline int snd_soc_usb_device_offload_available(struct device *dev)
+{
+ return -ENODEV;
+}
+
static inline int snd_soc_usb_prepare_session(struct snd_soc_usb *usb, int card_idx,
int pcm_idx)
{
diff --git a/sound/soc/soc-usb.c b/sound/soc/soc-usb.c
index 636d7a300039..a64bfbd91bf3 100644
--- a/sound/soc/soc-usb.c
+++ b/sound/soc/soc-usb.c
@@ -493,6 +493,26 @@ int snd_soc_usb_find_supported_format(int card_idx,
}
EXPORT_SYMBOL_GPL(snd_soc_usb_find_supported_format);

+/**
+ * snd_soc_usb_device_offload_available() - Fetch BE DAI link sound card
+ * @dev: the device to find in SOC USB
+ *
+ * Finds the component linked to a specific SOC USB instance, and returns
+ * the sound card number for the platform card supporting offloading.
+ *
+ */
+int snd_soc_usb_device_offload_available(struct device *dev)
+{
+ struct snd_soc_usb *ctx;
+
+ ctx = snd_soc_find_usb_ctx(dev);
+ if (!ctx)
+ return -ENODEV;
+
+ return ctx->component->card->snd_card->number;
+}
+EXPORT_SYMBOL_GPL(snd_soc_usb_device_offload_available);
+
/**
* snd_soc_usb_allocate_port() - allocate a SOC USB device
* @component: USB DPCM backend DAI component

2024-05-08 16:17:21

by Pierre-Louis Bossart

Subject: Re: [PATCH v21 33/39] ASoC: usb: Fetch ASoC sound card information

> +/**
> + * snd_soc_usb_device_offload_available() - Fetch BE DAI link sound card
> + * @dev: the device to find in SOC USB
> + *
> + * Finds the component linked to a specific SOC USB instance, and returns
> + * the sound card number for the platform card supporting offloading.
> + *
> + */
> +int snd_soc_usb_device_offload_available(struct device *dev)
> +{
> + struct snd_soc_usb *ctx;
> +
> + ctx = snd_soc_find_usb_ctx(dev);
> + if (!ctx)
> + return -ENODEV;
> +
> + return ctx->component->card->snd_card->number;
> +}

Presumably there's a notification to help applications discard this
information on removal?

2024-05-09 00:14:22

by Wesley Cheng

Subject: Re: [PATCH v21 33/39] ASoC: usb: Fetch ASoC sound card information

Hi Pierre,

On 5/7/2024 2:33 PM, Pierre-Louis Bossart wrote:
>
>> +/**
>> + * snd_soc_usb_device_offload_available() - Fetch BE DAI link sound card
>> + * @dev: the device to find in SOC USB
>> + *
>> + * Finds the component linked to a specific SOC USB instance, and returns
>> + * the sound card number for the platform card supporting offloading.
>> + *
>> + */
>> +int snd_soc_usb_device_offload_available(struct device *dev)
>> +{
>> + struct snd_soc_usb *ctx;
>> +
>> + ctx = snd_soc_find_usb_ctx(dev);
>> + if (!ctx)
>> + return -ENODEV;
>> +
>> + return ctx->component->card->snd_card->number;
>> +}
>
> Presumably there's a notification to help applications discard this
> information on removal?

If the platform/ASoC sound card is removed then the USB BE DAI is going
to be unregistered from SOC USB. This would lead to the
snd_soc_find_usb_ctx() to return with -ENODEV to the USB SND offload
kcontrol call.

Thanks
Wesley Cheng