Clemens Ladisch wrote:

I've got several reports that devices no longer work since UAC2 support got added. But I've just noticed this is not related to the interface class but to the interface protocol: the new code added checks for UAC_VERSION_1 or _2, but real devices apparently write just random junk into this field. (For vendor-specific interfaces, they are actually justified to do so.)

We need something like the following (untested), unless you have a better idea:

I retro-fitted Clemens' patch to kernel 2.6.35 and tested it. There is a problem in card.c and endpoint.c in that KERN_WARN needs to be KERN_WARNING, but otherwise the patch works. I get this in dmesg:

ALSA sound/usb/endpoint.c:279: 2:1:1: unknown interface protocol 0xff, assuming v1 ALSA sound/usb/endpoint.c:439: 2:1:1: add audio endpoint 0x1 ALSA sound/usb/endpoint.c:279: 2:2:1: unknown interface protocol 0xff, assuming v1 ALSA sound/usb/endpoint.c:439: 2:2:1: add audio endpoint 0x81 ALSA sound/usb/endpoint.c:279: 2:2:2: unknown interface protocol 0xff, assuming v1 ALSA sound/usb/endpoint.c:439: 2:2:2: add audio endpoint 0x81 ALSA sound/usb/clock.c:243: current rate 48000 is different from the runtime rate 96000

It is still necessary to have the following bit of code in endpoint.c, otherwise sample rates of 44100 or 88200 do not work (the original problem). I think there should be a standard name instead of using 0x09, something like UAC_EP_CS_ATTR_ADAPTIVE, this would have to be defined somewhere.

diff -rupN /sound/usb/endpoint.c /sound/usb/endpoint.c --- /sound/usb/endpoint.c +++ /sound/usb/endpoint.c @@ -403,11 +405,15 @@ int snd_usb_parse_audio_endpoints(struct break; case USB_ID(0x041e, 0x3020): /* Creative SB Audigy 2 NX */ case USB_ID(0x0763, 0x2003): /* M-Audio Audiophile USB */ - case USB_ID(0x0763, 0x2080): /* M-Audio Fast Track Ultra 8 */ - case USB_ID(0x0763, 0x2081): /* M-Audio Fast Track Ultra 8R */ /* doesn't set the sample rate attribute, but supports it */ fp->attributes |= UAC_EP_CS_ATTR_SAMPLE_RATE; break; + case USB_ID(0x0763, 0x2080): /* M-Audio Fast Track Ultra */ + case USB_ID(0x0763, 0x2081): /* M-Audio Fast Track Ultra 8R */ + /* force playback sync to adaptive only and turn off async*/ + if (stream == SNDRV_PCM_STREAM_PLAYBACK) + fp->ep_attr = 0x09; + break; case USB_ID(0x047f, 0x0ca1): /* plantronics headset */ case USB_ID(0x077d, 0x07af): /* Griffin iMic (note that there is an older model 77d:223) */