Hi, thanks for the information. I just commented the following part of mixer.c if (hdr->bLength < 7 || !csize || hdr->bLength < 7 + csize) { snd_printk(KERN_ERR "usbaudio: unit %u: invalid UAC_FEATURE_UNIT descriptor\n", unitid); return -EINVAL; } and compiled alsa-driver, alsa-lib, alsa-tools and alsa-oss basically following the instructions here: http://alsa.opensrc.org/Quick_Install. There were warnings during the compiling process but no errors. The new driver might work, I have the following output from dmesg [ 41.064090] usb 1-2: new high-speed USB device number 5 using ehci_hcd [ 41.200270] ALSA mixer.c:352 cannot get ctl value: req = 0x83, wValue = 0x200, wIndex = 0x200, type = 4 [ 41.201129] ALSA mixer.c:352 cannot get ctl value: req = 0x83, wValue = 0x200, wIndex = 0x200, type = 4 [ 41.201230] ALSA mixer.c:352 cannot get ctl value: req = 0x83, wValue = 0x200, wIndex = 0x200, type = 4 and from aplay -l **** List of PLAYBACK Hardware Devices **** card 0: Intel [HDA Intel], device 0: AD198x Analog [AD198x Analog] Subdevices: 1/1 Subdevice #0: subdevice #0 card 0: Intel [HDA Intel], device 1: AD198x Digital [AD198x Digital] Subdevices: 1/1 Subdevice #0: subdevice #0 card 1: F23455936 [Fireface UCX (23455936)], device 0: USB Audio [USB Audio] Subdevices: 1/1 Subdevice #0: subdevice #0 The fireface ucx moreover appears in the system settings / sound menue. I did not test whether the device actually produces sound, I hope I can do that tomorrow. I have one more question concerning the usb-audio-2.0 standard: How many in/out channels am I able to run (on linux) ? RME claim on their website, that it is possible to use 8 in-channels on the ipad, i.e. using the class compliance mode. I am asking this question because JACK seems to have a problem with the in/out channels: 02:12:01.744 D-BUS: SetParameterValue('driver:inchannels', '1'): Parameter value type mismatch: was expecting 'i', got 'u'. (org.jackaudio.Error.InvalidArgs) The same error occurs for the outchannels and I tried the values 1,2,8 for the nummer of channels but I always get the same error. Best, Florian Quoting Daniel Mack <zonque@xxxxxxxxx>: > On 02.10.2012 09:27, Clemens Ladisch wrote: >> Florian Hanisch wrote: >>>>> usbaudio: unit 2: invalid UAC_FEATURE_UNIT descriptor >>> >>> AudioControl Interface Descriptor: >>> bLength 10 >>> bDescriptorType 36 >>> bDescriptorSubtype 6 (FEATURE_UNIT) >>> bUnitID 2 >>> bSourceID 3 >>> bmaControls( 0) 0x0000000c >>> Volume Control (read/write) >>> iFeature 0 >> >> This descriptor is perfectly OK; the driver has a bug. >> The following code in parse_audio_feature_unit() in sound/usb/mixer.c >> is valid only for v1 devices; please try to just remove it: >> >> if (hdr->bLength < 7 || !csize || hdr->bLength < 7 + csize) { >> snd_printk(KERN_ERR "usbaudio: unit %u: invalid UAC_FEATURE_UNIT >> descriptor\n", unitid); >> return -EINVAL; >> } > > Yes, interesting this never got triggered before. The 7 should be a 6 in > v2 case ... > > > ------------------------------------------------------------------------------ Don't let slow site performance ruin your business. Deploy New Relic APM Deploy New Relic app performance management and know exactly what is happening inside your Ruby, Python, PHP, Java, and .NET app Try New Relic at no cost today and get our sweet Data Nerd shirt too! http://p.sf.net/sfu/newrelic-dev2dev _______________________________________________ Alsa-user mailing list Alsa-user@xxxxxxxxxxxxxxxxxxxxx https://lists.sourceforge.net/lists/listinfo/alsa-user