On Thu, Mar 24, 2022 at 05:10:42PM +0900, Oh Eomji wrote:
In mobile, a co-processor can be used with USB audio to improve power consumption. To support this type of hardware, hooks need to be added to the USB audio subsystem to be able to call into the hardware when needed.
The main operation of the call-backs are:
- Initialize the co-processor by transmitting data when initializing.
- Change the co-processor setting value through the interface function.
- Configure sampling rate
- pcm open/close
- other housekeeping
Known issues:
- This only supports one set of callback hooks, meaning that this only works if there is one type of USB controller in the system. This should be changed to be a per-host-controller interface instead of one global set of callbacks.
Signed-off-by: JaeHun Jung jh0801.jung@samsung.com Signed-off-by: Oh Eomji eomji.oh@samsung.com
sound/usb/card.c | 119 +++++++++++++++++++++++++++++++++++++++++++++++++++ sound/usb/card.h | 20 +++++++++ sound/usb/usbaudio.h | 45 +++++++++++++++++++ 3 files changed, 184 insertions(+)
diff --git a/sound/usb/card.c b/sound/usb/card.c index 3769622..bd59311 100644 --- a/sound/usb/card.c +++ b/sound/usb/card.c @@ -117,6 +117,117 @@ 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_audio_vendor_ops *usb_vendor_ops;
+int snd_vendor_set_ops(struct snd_usb_audio_vendor_ops *ops) +{
- if ((!ops->connect) ||
(!ops->disconnect) ||(!ops->set_interface) ||(!ops->set_rate) ||(!ops->set_pcm_buf) ||(!ops->set_pcm_intf) ||(!ops->set_pcm_connection) ||(!ops->set_pcm_binterval) ||(!ops->usb_add_ctls))return -EINVAL;- usb_vendor_ops = ops;
- return 0;
+} +EXPORT_SYMBOL_GPL(snd_vendor_set_ops);
+struct snd_usb_audio_vendor_ops *snd_vendor_get_ops(void) +{
- return usb_vendor_ops;
+}
This is the function you need to fix up, and add proper reference counting to, in order to solve your "this breaks with multiple USB controllers" problem. So this really should not be all that difficult of a task. Why has it taken years to do so?
thanks,
greg k-h