Am 09.03.24 um 18:29 schrieb Joonas Kankaala:
> This fixes the invalid bInterfaceProtocol value 0x04 in the USB audio
> AudioControl descriptors. It should be zero. While Linux and Windows
> forgive this error, macOS 14 Sonoma does not. The usb-audio device does
> not appear in macOS sound settings even though the device is recognized
> and shows up in USB system information. According to the USB audio class
> specs 1.0-4.0, valid values are 0x00, 0x20, 0x30 and 0x40. (Note also
> that Linux prints the warning "unknown interface protocol 0x4, assuming
> v1", but then proceeds as if the value was zero.)
>
> This also fixes the invalid wTotalLength value in the multi-channel
> setup AudioControl interface header descriptor (used when multi=on
> and out.mixing-engine off). The combined length of all the descriptors
> there add up to 0x37, not 0x38. In Linux, "lsusb -D ..." displays
> incomplete descriptor information when this length is incorrect.
>
> Signed-off-by: Joonas Kankaala <joonas.a.kanka...@gmail.com>
lsusb also misinterprets the invalid interface protocol 0x4 and uses
0x30 instead.
Reviewed-by: Volker Rümelin <vr_q...@t-online.de>
> ---
> hw/usb/dev-audio.c | 4 +---
> 1 file changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/hw/usb/dev-audio.c b/hw/usb/dev-audio.c
> index d5ac1f8962..1897fff9e6 100644
> --- a/hw/usb/dev-audio.c
> +++ b/hw/usb/dev-audio.c
> @@ -124,7 +124,6 @@ static const USBDescIface desc_iface[] = {
> .bNumEndpoints = 0,
> .bInterfaceClass = USB_CLASS_AUDIO,
> .bInterfaceSubClass = USB_SUBCLASS_AUDIO_CONTROL,
> - .bInterfaceProtocol = 0x04,
> .iInterface = STRING_USBAUDIO_CONTROL,
> .ndesc = 4,
> .descs = (USBDescOther[]) {
> @@ -282,7 +281,6 @@ static const USBDescIface desc_iface_multi[] = {
> .bNumEndpoints = 0,
> .bInterfaceClass = USB_CLASS_AUDIO,
> .bInterfaceSubClass = USB_SUBCLASS_AUDIO_CONTROL,
> - .bInterfaceProtocol = 0x04,
> .iInterface = STRING_USBAUDIO_CONTROL,
> .ndesc = 4,
> .descs = (USBDescOther[]) {
> @@ -293,7 +291,7 @@ static const USBDescIface desc_iface_multi[] = {
> USB_DT_CS_INTERFACE, /* u8 bDescriptorType */
> DST_AC_HEADER, /* u8 bDescriptorSubtype */
> U16(0x0100), /* u16 bcdADC */
> - U16(0x38), /* u16 wTotalLength */
> + U16(0x37), /* u16 wTotalLength */
> 0x01, /* u8 bInCollection */
> 0x01, /* u8 baInterfaceNr */
> }
