On 1/25/23 21:14, Wesley Cheng wrote:
Some platforms may want to register its USB port to be handled by the ASoC framework. Audio playback/capture support is also handled entirely by the vendor ASoC drivers.
Can you clarify what you mean by 'port'?
+/**
- snd_soc_usb_add_port() - Add a USB backend port
- @dev: USB backend device
- @connection_cb: connection status callback
- Register a USB backend device to the SND USB SOC framework. Memory is
- allocated as part of the USB backend device.
- */
+struct snd_soc_usb *snd_soc_usb_add_port(struct device *dev,
int (*connection_cb)(struct snd_soc_usb *usb, int card_idx,int 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;
- 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);
Can a backend have more than one ports?
Is there any relationship between port and USB endpoint, and if yes where is this determined?
+/**
- 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.
- */
+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;
+} +EXPORT_SYMBOL_GPL(snd_soc_usb_remove_port);
What happens if the ASoC driver probes/initialize AFTER the USB device is plugged?
Likewise, can the ASoC driver be removed 'safely' with a fallback to normal non-offloaded operation happening on remove?
+/**
- 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 USB backend selects, which device to enable offloading on.
- */
+int snd_soc_usb_connect(struct device *usbdev, int card_idx) +{
- struct snd_soc_usb *ctx;
- if (!usbdev)
return -ENODEV;- ctx = snd_soc_find_usb_ctx(usbdev);
- if (!ctx)
return -ENODEV;- if (ctx->connection_status_cb)
ctx->connection_status_cb(ctx, card_idx, 1);- return 0;
+} +EXPORT_SYMBOL_GPL(snd_soc_usb_connect);
+/**
- snd_soc_usb_connect() - Notification of USB device connection
- @usbdev: USB bus device
- Notify of a new USB SND device disconnection to the USB backend.
- */
+int snd_soc_usb_disconnect(struct device *usbdev) +{
- struct snd_soc_usb *ctx;
- if (!usbdev)
return -ENODEV;- ctx = snd_soc_find_usb_ctx(usbdev);
- if (!ctx)
return -ENODEV;- if (ctx->connection_status_cb)
ctx->connection_status_cb(ctx, -1, 0);- return 0;
+} +EXPORT_SYMBOL_GPL(snd_soc_usb_disconnect);
Similar concern on connect/disconnect, does this assume any specific order for the driver probe?