Hi, when I run amixer -D hw:4 controls | sort -n -t = -k2 I get the output below numid=1,iface=MIXER,name='KKKKKKKKKKKKKÃÃÃÃÃÃÃÃÃÃÃ Switch' numid=2,iface=CARD,name='Internal Validity' numid=3,iface=CARD,name='S/PDIF Validity' numid=4,iface=CARD,name='ADAT Validity' numid=5,iface=MIXER,name='Scarlett 18i20 USB-Sync Clock Source' numid=6,iface=MIXER,name=' Switch' numid=7,iface=CARD,name='Keep Interface' numid=8,iface=MIXER,name='Master Playback Switch' numid=9,iface=MIXER,name='Master Playback Volume' numid=10,iface=MIXER,name='Master 1 (Monitor) Playback Switch' numid=11,iface=MIXER,name='Master 1 (Monitor) Playback Volume' ... lots of extra lines ... Please note the lines for numid=1 and numid=6. The first one contains some garbage and the 2nd one look like it should start with another word. I now added some debug printing here: https://github.com/torvalds/linux/blob/master/sound/usb/mixer_scarlett.c#L562 and get output in dmesg: [ 2971.642137] usb 1-2: Product: Scarlett 18i20 USB [ 2971.642141] usb 1-2: Manufacturer: Focusrite [ 2971.709773] new ctrl: name='Master Playback Switch', index=10, offset=1, num=0: numid=8 [ 2971.709781] new ctrl: name='Master Playback Volume', index=10, offset=2, num=0: numid=9 [ 2971.709788] new ctrl: name='Master 1 (Monitor) Playback Switch', index=10, offset=1, num=1: numid=10 So the first 8 controls are added somewhere else. Looks like this is from mixer.c and after echo -n 'file sound/usb/mixer.c +p' >/sys/kernel/debug/dynamic_debug/control I get [ 4405.855432] usb 1-2: [51] PU [KKKKKKKKKKKKKÃÃÃÃÃÃÃÃÃÃÃ Switch] ch = 1, val = 0/1 [ 4405.856423] usb 1-2: [52] PU [ Switch] ch = 1, val = 0/1 I now added more debug prints into https://github.com/torvalds/linux/blob/master/sound/usb/mixer.c#L2431 and its the code that calls snd_usb_copy_string_desc() [ 5750.124123] usb 1-2: nameid=90, len=35 [ 5750.124157] usb 1-2: [51] PU [KKKKKKKKKKKKKÃÃÃÃÃÃÃÃÃÃÃ Switch] ch = 1, val = 0/1 [ 5750.125241] usb 1-2: nameid=82, len=1 [ 5750.125260] usb 1-2: [52] PU [ Switch] ch = 1, val = 0/1 In both cases the returned len seems wrong and the function does not seems to copy any useful string here. snd_usb_copy_string_desc() is just a wrapper around usb_string(). Is my hardware returning bogus data in usb descriptors? Can this be address through some quirks table? Any other ideas? Thanks! Stefan _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx https://mailman.alsa-project.org/mailman/listinfo/alsa-devel
