[alsa-devel] [PATCH 2/3 v4] 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.
>
> +++ b/sound/usb/mixer_quirks.c
> +static int snd_mbox1_switch_put(struct snd_kcontrol *kctl,
> +				struct snd_ctl_elem_value *ucontrol)
> +{
> ...
> +		down_read(&chip->shutdown_rwsem);

When I wrote "semaphore", I meant this one.


Regards,
Clemens