[alsa-devel] [PATCH 1/2 v3] ALSA: usb-audio: Add mixer control for Digidesign mbox 1 clock source

[Clemens Ladisch]

Damien Zammit wrote:
> This patch provides the infrastructure for the Digidesign Mbox 1
> to have a mixer control for selecting the clock source.
> Valid options are Internal and S/PDIF external sync.
> A non-documented command is sent to the device to enable this feature
> found by reverse engineering and bus snooping.
>
> Signed-off-by: Damien Zammit <damien at zamaudio.com>
> ---
>  sound/usb/mixer_maps.c   |   9 +++
>  sound/usb/mixer_quirks.c | 142 +++++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 151 insertions(+)
>
> +++ b/sound/usb/mixer_maps.c
> +static int snd_mbox1_switch_put(struct snd_kcontrol *kctl,
> +				struct snd_ctl_elem_value *ucontrol)
> +{
> ...
> +		down_read(&chip->shutdown_rwsem);
> +		if (chip->shutdown) {
> +			err = -ENODEV;
> +		} else {
> +			/* Prepare for magic command to toggle clock source */
> +			err = snd_usb_ctl_msg(chip->dev,
> +				usb_rcvctrlpipe(chip->dev, 0), 0x81,
> +				USB_DIR_IN |
> +				USB_TYPE_CLASS |
> +				USB_RECIP_INTERFACE, 0x00, 0x500, buff, 1);
> +			if (err < 0)
> +				return err;

The semaphore is still locked.

> @@ -1605,6 +1740,13 @@ int snd_usb_mixer_apply_create_quirk(struct usb_mixer_interface *mixer)
>  					      snd_audigy2nx_proc_read);
>  		break;
>
> +	/* Digidesign Mbox 1 */
> +	case USB_ID(0x0dba, 0x1000):

The IDs are supposed to be sorted by their value.

> +		err = snd_mbox1_create_sync_switch(mixer);
> +		if (err < 0)
> +			break;
> +		break;

This if() is meaningless.


Regards,
Clemens