Re: [RFC PATCH v2 12/22] sound: usb: card: Introduce USB SND platform op callbacks

Hi Wesley,

It looks like your audio offload driver will fetch the required resources for a stream enable request. But we have different designs. In the integration with your patch set, we found we still need a call back function in card.c when the usb set interface is done, in which we would call the new API, xhci_get_xfer_resource(), to get the EP transfer ring address. Of course, we will try the platform_ops->connect_cb() first to see if it is able to cover what we need or not.

Thanks, Albert Wang

Albert Wang | Pixel USB Software | albertccwang@google.com | +886-918-695-245

On Thu, Jan 26, 2023 at 11:16 AM Wesley Cheng quic_wcheng@quicinc.com wrote:

Allow for different platforms to be notified on USB SND connect/disconnect seqeunces. This allows for platform USB SND modules to properly initialize and populate internal structures with references to the USB SND chip device.

Signed-off-by: Wesley Cheng quic_wcheng@quicinc.com

sound/usb/card.c | 28 ++++++++++++++++++++++++++++ sound/usb/card.h | 20 ++++++++++++++++++++ 2 files changed, 48 insertions(+)

diff --git a/sound/usb/card.c b/sound/usb/card.c index 26268ffb8274..803230343c16 100644 --- a/sound/usb/card.c +++ b/sound/usb/card.c @@ -117,6 +117,24 @@ MODULE_PARM_DESC(skip_validation, "Skip unit descriptor validation (default: no) static DEFINE_MUTEX(register_mutex); static struct snd_usb_audio *usb_chip[SNDRV_CARDS]; static struct usb_driver usb_audio_driver; +static struct snd_usb_platform_ops *platform_ops;

+int snd_usb_register_platform_ops(struct snd_usb_platform_ops *ops) +{

•   if (platform_ops)
  

•           return -EEXIST;
  

•   platform_ops = ops;
  

•   return 0;
  

+} +EXPORT_SYMBOL_GPL(snd_usb_register_platform_ops);

+int snd_usb_unregister_platform_ops(void) +{

•   platform_ops = NULL;
  

•   return 0;
  

+} +EXPORT_SYMBOL_GPL(snd_usb_unregister_platform_ops);

/*

• disconnect streams

@@ -910,6 +928,10 @@ static int usb_audio_probe(struct usb_interface *intf, usb_set_intfdata(intf, chip); atomic_dec(&chip->active); mutex_unlock(&register_mutex);

•   if (platform_ops->connect_cb)
  

•           platform_ops->connect_cb(intf, chip);
  

•   return 0;
  
  

  __error:

@@ -943,6 +965,9 @@ static void usb_audio_disconnect(struct usb_interface *intf) if (chip == USB_AUDIO_IFACE_UNUSED) return;

•   if (platform_ops->disconnect_cb)
  

•           platform_ops->disconnect_cb(intf);
  

•   card = chip->card;
  
    mutex_lock(&register_mutex);
  

@@ -1087,6 +1112,9 @@ static int usb_audio_suspend(struct usb_interface *intf, pm_message_t message) chip->system_suspend = chip->num_suspended_intf; }

•   if (platform_ops->suspend_cb)
  

•           platform_ops->suspend_cb(intf, message);
  

•   return 0;
  

}

diff --git a/sound/usb/card.h b/sound/usb/card.h index 40061550105a..2249c411c3a1 100644 --- a/sound/usb/card.h +++ b/sound/usb/card.h @@ -206,4 +206,24 @@ struct snd_usb_stream { struct list_head list; };

+struct snd_usb_platform_ops {

•   void (*connect_cb)(struct usb_interface *intf, struct snd_usb_audio *chip);
  

•   void (*disconnect_cb)(struct usb_interface *intf);
  

•   void (*suspend_cb)(struct usb_interface *intf, pm_message_t message);
  

+};

+#if IS_ENABLED(CONFIG_SND_USB_AUDIO) +int snd_usb_register_platform_ops(struct snd_usb_platform_ops *ops); +int snd_usb_unregister_platform_ops(void); +#else +int snd_usb_register_platform_ops(struct snd_usb_platform_ops *ops) +{

•   return -EOPNOTSUPP;
  

+}

+int snd_usb_unregister_platform_ops(void) +{

•   return -EOPNOTSUPP;
  

+} +#endif /* IS_ENABLED(CONFIG_SND_USB_AUDIO) */ #endif /* __USBAUDIO_CARD_H */