Hi Greg,
On 2/10/2023 2:49 PM, Wesley Cheng wrote:
Hi Greg,
On 1/28/2023 5:28 AM, Greg KH wrote:
On Wed, Jan 25, 2023 at 07:14:14PM -0800, Wesley Cheng 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@xxxxxxxxxxx>
---
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;
You can not have a single "platform_ops" pointer, this HAS to be
per-bus.
Agreed.
I looked at seeing how we could implement this at a per bus level, but
the USB class driver model doesn't exactly have a good framework for
supporting this. Reason being is because, at the time of the USB SND
class driver initialization, there is a big chance that there isn't a
USB bus registered in the system, so the point of adding the operations
is not clear. However, we need to ensure that we've added the
platform/driver operations before any USB SND devices are detected.
To add to the above, in case of OTG/DRD (dual role) designs, the USB
HCD/bus isn't created until we move into the host role. At that time,
using DWC3 as an example, we will create the XHCI platform device, and
probe the USB HCD, where a USB bus is created.
In general, we currently think this USB offload driver should co-exist
with the USB SND class driver, which handles all devices connected
across every bus. We can add a check to the platform connect routine to
ensure that there is a reference to the USB backend. If so, then that
particular USB bus/sysdev can be supported by the audio DSP. That way,
we do not falsely populate USB SND cards which are present on another
USB bus/controller.
Thanks
Wesley Cheng
