On 10/17/23 15:00, Wesley Cheng wrote:
> Some platforms may have support for offloading USB audio devices to a
> dedicated audio DSP. Introduce a set of APIs that allow for management of
> USB sound card and PCM devices enumerated by the USB SND class driver.
> This allows for the ASoC components to be aware of what USB devices are
USB devices or USB endpoints? or both?
> available for offloading.
> +/**
> + * struct snd_soc_usb_device
> + * @card_idx - sound card index associated with USB device
> + * @chip_idx - USB sound chip array index
> + * @num_playback - number of playback streams
> + * @num_capture - number of capture streams
presumably excluding explicit feedback streams?
> + **/
> +struct snd_soc_usb_device {
> + int card_idx;
> + int chip_idx;
> + int num_playback;
> + int num_capture;
> +};
> +
> +/**
> + * struct snd_soc_usb
> + * @list - list head for SND SOC struct list
> + * @dev - USB backend device reference
> + * @component - reference to ASoC component
> + * @connection_status_cb - callback to notify connection events
> + * @priv_data - driver data
> + **/
> +struct snd_soc_usb {
> + struct list_head list;
> + struct device *dev;
usbdev for consistency with the API below?
> + struct snd_soc_component *component;
could you use component only and infer the device from component->dev?
> + int (*connection_status_cb)(struct snd_soc_usb *usb,
> + struct snd_soc_usb_device *sdev, bool connected);
> + void *priv_data;
> +};
> +
> +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_get_priv_data(struct device *usbdev);
> +
> +struct snd_soc_usb *snd_soc_usb_add_port(struct device *dev, void *priv,
struct device *usbdev for consistency ?
> + int (*connection_cb)(struct snd_soc_usb *usb,
> + struct snd_soc_usb_device *sdev, bool connected));
> +int snd_soc_usb_remove_port(struct device *dev);
struct device *usbdev for consistency ?
> +struct snd_soc_usb *snd_soc_usb_add_port(struct device *dev, void *priv,
> + int (*connection_cb)(struct snd_soc_usb *usb,
> + struct snd_soc_usb_device *sdev, bool connected))> +{
> + struct snd_soc_usb *usb;
> +
> + usb = devm_kzalloc(dev, sizeof(*usb), GFP_KERNEL);
> + if (!usb)
> + return ERR_PTR(-ENOMEM);
> +
> + usb->connection_status_cb = connection_cb;
> + usb->dev = dev;
> + usb->priv_data = priv;
> +
> + mutex_lock(&ctx_mutex);
> + list_add_tail(&usb->list, &usb_ctx_list);
> + mutex_unlock(&ctx_mutex);
> +
> + return usb;
> +}
> +EXPORT_SYMBOL_GPL(snd_soc_usb_add_port);
> +
> +/**
> + * snd_soc_usb_remove_port() - Remove a USB backend port
> + * @dev: USB backend device
> + *
> + * Remove a USB backend device from USB SND SOC. Memory is freed when USB
> + * backend is removed.
when the USB backend driver is unbound?
> + *
> + */
> +int snd_soc_usb_remove_port(struct device *dev)
> +{
> + struct snd_soc_usb *ctx, *tmp;
> +
> + mutex_lock(&ctx_mutex);
> + list_for_each_entry_safe(ctx, tmp, &usb_ctx_list, list) {
> + if (ctx->dev == dev) {
> + list_del(&ctx->list);
> + break;
> + }
> + }
> + mutex_unlock(&ctx_mutex);
> +
> + return 0;
can this return void to align with the current trend?
> +}
> +EXPORT_SYMBOL_GPL(snd_soc_usb_remove_port);
> +
> +/**
> + * snd_soc_usb_connect() - Notification of USB device connection
> + * @usbdev: USB bus device
> + * @card_idx: USB SND card instance
> + *
> + * Notify of a new USB SND device connection. The card_idx can be used to
> + * handle how the DPCM backend selects, which device to enable USB offloading
> + * on.
card_idx is not used below, and I don't see how this relates to a
notification?
> + *
> + */
> +int snd_soc_usb_connect(struct device *usbdev, struct snd_soc_usb_device *sdev)
> +{
> + struct snd_soc_usb *ctx;
> + struct device_node *node;
> +
> + if (!usbdev)
> + return -ENODEV;
> +
> + node = snd_soc_find_phandle(usbdev);
> + if (IS_ERR(node))
> + return -ENODEV;
> +
> + ctx = snd_soc_find_usb_ctx(node);
> + of_node_put(node);
> + if (!ctx)
> + return -ENODEV;
> +
> + if (ctx->connection_status_cb)
> + ctx->connection_status_cb(ctx, sdev, true);
> +
> + return 0;
> +}
