Re: UAC2 clock selector for AudioBox 1818VSL

[Daniel Mack <zonque@gmail.com>]

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On 07.09.2012 19:57, louis@museresearch.com wrote:
> Hi Daniel,
>   Thanks for the quick reply. I am able to set the clock on my Mac, though
> I do need to do further tests and make sure that the sync is actually
> reliable there. The setting is available from the built-in, standard OS
> X audio setup application "Audio MIDI Setup".
> 
> There should be a S/PDIF clock signal going to the digital inputs on the
> device. Some of the other controls such as per-channel mute also appear to
> work. I've also attached the lsusb output.
> 
> There are some other details that may be relevant, but I didn't want to
> make my initial post too long/confusing because these extra details may
> end up just being a red herring: Each mixer element name (as seen in
> amixer) is prefixed with "AudioBox 1818 VSL Clock Selector" even if it is
> not a clock selector.

That strange but I believe not related. We should still fix that :)

> I am confident though that the control I've been
> playing with is the clock selector because it lists the different clock
> types as options. I also see this when I plug the device in or load the
> ALSA driver:
> 
> ALSA sound/usb/mixer.c:342 cannot get ctl value: req = 0x83, wValue =
> 0x201, wIndex = 0xa00, type = 4
> ALSA sound/usb/mixer.c:846 10:0: cannot get min/max values for control 2
> (id 10)
> ALSA sound/usb/mixer.c:342 cannot get ctl value: req = 0x83, wValue =
> 0x200, wIndex = 0xa00, type = 4
> ALSA sound/usb/mixer.c:846 10:0: cannot get min/max values for control 2
> (id 10)
> ALSA sound/usb/mixer.c:342 cannot get ctl value: req = 0x83, wValue =
> 0x201, wIndex = 0xb00, type = 4
> ALSA sound/usb/mixer.c:846 11:0: cannot get min/max values for control 2
> (id 11)
> ALSA sound/usb/mixer.c:342 cannot get ctl value: req = 0x83, wValue =
> 0x200, wIndex = 0xb00, type = 4
> ALSA sound/usb/mixer.c:846 11:0: cannot get min/max values for control 2
> (id 11)

Do you see any messages when you try to set the clock selector with amixer?

If you're running a recent kernel, try the following patch. That will
produce log messages for each mixer related control packet that is sent
out to the device.


Thanks,
Daniel




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diff --git a/sound/usb/mixer.c b/sound/usb/mixer.c
index 4f40ba8..fce9b88 100644
--- a/sound/usb/mixer.c
+++ b/sound/usb/mixer.c
@@ -446,6 +446,9 @@ int snd_usb_mixer_set_ctl_value(struct usb_mixer_elem_info *cval,
 				    USB_RECIP_INTERFACE | USB_TYPE_CLASS | USB_DIR_OUT,
 				    validx, snd_usb_ctrl_intf(chip) | (cval->id << 8),
 				    buf, val_len) >= 0) {
+			snd_printk(" DEBUG: %s(): request %08x requesttype %08x, value %04x, index %04x, size %d\n",
+					__func__, request, USB_RECIP_INTERFACE | USB_TYPE_CLASS | USB_DIR_OUT,
+					validx, snd_usb_ctrl_intf(chip) | (cval->id << 8), val_len);
 			snd_usb_autosuspend(chip);
 			return 0;
 		}

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