Re: uac2/hid gadget issues on Win10 hosts

I'm attempting to create a composite gadget device that uses uac2 and
hid functions (speakerphone), using the latest kernel branch
(rpi-5.14.y) on a rpi4 device.
Windows10 host does not recognize the device as an audio usb device.
In order to get it recognized, I had to use c_sync in adaptive mode,
as well as make the following adjustments:

diff --git a/drivers/usb/gadget/function/f_uac2.c

b/drivers/usb/gadget/function/f_uac2.c
index ae29ff2b2b68..74a221939ca0 100644

--- a/drivers/usb/gadget/function/f_uac2.c
+++ b/drivers/usb/gadget/function/f_uac2.c

@@ -177,7 +177,7 @@ static struct uac2_input_terminal_descriptor

io_in_it_desc = {

         .bDescriptorSubtype = UAC_INPUT_TERMINAL,
         /* .bTerminalID = DYNAMIC */
-       .wTerminalType = cpu_to_le16(UAC_INPUT_TERMINAL_UNDEFINED),
+       .wTerminalType = cpu_to_le16(UAC_INPUT_TERMINAL_MICROPHONE),
         .bAssocTerminal = 0,
         /* .bCSourceID = DYNAMIC */
         .iChannelNames = 0,

@@ -205,7 +205,7 @@ static struct uac2_output_terminal_descriptor

io_out_ot_desc = {

         .bDescriptorSubtype = UAC_OUTPUT_TERMINAL,
         /* .bTerminalID = DYNAMIC */
-       .wTerminalType = cpu_to_le16(UAC_OUTPUT_TERMINAL_UNDEFINED),
+       .wTerminalType = cpu_to_le16(UAC_OUTPUT_TERMINAL_SPEAKER),
         .bAssocTerminal = 0,
         /* .bSourceID = DYNAMIC */
         /* .bCSourceID = DYNAMIC */

@@ -216,7 +216,7 @@ static struct uac2_ac_header_descriptor ac_hdr_desc = {
         .bLength = sizeof ac_hdr_desc,
         .bDescriptorType = USB_DT_CS_INTERFACE,

-       .bDescriptorSubtype = UAC_MS_HEADER,
+       .bDescriptorSubtype = UAC_HEADER,
         .bcdADC = cpu_to_le16(0x200),
         .bCategory = UAC2_FUNCTION_IO_BOX,
         /* .wTotalLength = DYNAMIC */

@@ -400,7 +400,7 @@ static struct usb_endpoint_descriptor fs_epin_desc = {
         .bDescriptorType = USB_DT_ENDPOINT,

         .bEndpointAddress = USB_DIR_IN,
-       .bmAttributes = USB_ENDPOINT_XFER_ISOC | USB_ENDPOINT_SYNC_ASYNC,
+       .bmAttributes = USB_ENDPOINT_XFER_ISOC | USB_ENDPOINT_SYNC_SYNC,
         /* .wMaxPacketSize = DYNAMIC */
         .bInterval = 1,
  };

@@ -409,7 +409,7 @@ static struct usb_endpoint_descriptor hs_epin_desc = {
         .bLength = USB_DT_ENDPOINT_SIZE,
         .bDescriptorType = USB_DT_ENDPOINT,

-       .bmAttributes = USB_ENDPOINT_XFER_ISOC | USB_ENDPOINT_SYNC_ASYNC,
+       .bmAttributes = USB_ENDPOINT_XFER_ISOC | USB_ENDPOINT_SYNC_SYNC,
         /* .wMaxPacketSize = DYNAMIC */
         .bInterval = 4,
  };

@@ -419,7 +419,7 @@ static struct usb_endpoint_descriptor ss_epin_desc = {
         .bDescriptorType = USB_DT_ENDPOINT,

         .bEndpointAddress = USB_DIR_IN,
-       .bmAttributes = USB_ENDPOINT_XFER_ISOC | USB_ENDPOINT_SYNC_ASYNC,
+       .bmAttributes = USB_ENDPOINT_XFER_ISOC | USB_ENDPOINT_SYNC_SYNC,
         /* .wMaxPacketSize = DYNAMIC */
         .bInterval = 4,
  };
--