[alsa-devel] [PATCH RFC] ALSA: usb-audio: add front jack channel selector for EMU0204

[Takashi Iwai]

At Thu, 11 Jul 2013 22:57:51 +0300,
Vasily Khoruzhick wrote:
> 
> Add support for front jack channel selector which is present on EMU0204.
> It allows to get 4 channels out of this soundcard.
> 
> Tested-by: Yury Bushmelev <jay at jay-tech.ru>
> Signed-off-by: Vasily Khoruzhick <anarsoul at gmail.com>
> ---
> Control request looks like generic UAC_SET_CUR request, but with a bit weird values,
> valid values are { 0x01, 0x01} and { 0x01, 0x02 }, and there's no such control type ATM.
> I'm not well familiar with UAC so any suggestins how to get rid of custom control req are welcome!

snd_usb_ctl_msg() call should be rewritten not to pass magic numbers
but use constants, e.g.
  0x01 = UAC_SET_CUR,
  0x21 = USB_RECIP_INTERFACE | USB_TYPE_CLASS | USB_DIR_OUT
...

And, in this case, it'd be more natural to implement as an enum
control instead of a switch.


thanks,

Takashi


>  sound/usb/mixer.h        |  1 +
>  sound/usb/mixer_quirks.c | 77 ++++++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 78 insertions(+)
> 
> diff --git a/sound/usb/mixer.h b/sound/usb/mixer.h
> index aab80df..4a5f001 100644
> --- a/sound/usb/mixer.h
> +++ b/sound/usb/mixer.h
> @@ -23,6 +23,7 @@ struct usb_mixer_interface {
>  
>  	u8 audigy2nx_leds[3];
>  	u8 xonar_u1_status;
> +	u8 emu0204_ch_switch;
>  };
>  
>  #define MAX_CHANNELS	16	/* max logical channels */
> diff --git a/sound/usb/mixer_quirks.c b/sound/usb/mixer_quirks.c
> index ebe9144..dc9a397 100644
> --- a/sound/usb/mixer_quirks.c
> +++ b/sound/usb/mixer_quirks.c
> @@ -430,6 +430,76 @@ static void snd_audigy2nx_proc_read(struct snd_info_entry *entry,
>  	}
>  }
>  
> +/* EMU0204 */
> +#define snd_emu0204_ch_switch_info		snd_ctl_boolean_mono_info
> +
> +static int snd_emu0204_ch_switch_get(struct snd_kcontrol *kcontrol,
> +				     struct snd_ctl_elem_value *ucontrol)
> +{
> +	struct usb_mixer_interface *mixer = snd_kcontrol_chip(kcontrol);
> +
> +	ucontrol->value.integer.value[0] = mixer->emu0204_ch_switch;
> +	return 0;
> +}
> +
> +static int snd_emu0204_ch_switch_put(struct snd_kcontrol *kcontrol,
> +				     struct snd_ctl_elem_value *ucontrol)
> +{
> +	struct usb_mixer_interface *mixer = snd_kcontrol_chip(kcontrol);
> +	int value = ucontrol->value.integer.value[0];
> +	int err, changed;
> +	unsigned char buf[2];
> +
> +	if (value > 1)
> +		return -EINVAL;
> +
> +	buf[0] = 0x01;
> +	buf[1] = value ? 0x02 : 0x01;
> +
> +	changed = value != mixer->emu0204_ch_switch;
> +	down_read(&mixer->chip->shutdown_rwsem);
> +	if (mixer->chip->shutdown) {
> +		err = -ENODEV;
> +		goto out;
> +	}
> +	err = snd_usb_ctl_msg(mixer->chip->dev,
> +		      usb_sndctrlpipe(mixer->chip->dev, 0), 0x1,
> +		      0x21,
> +		      0x0400, 0x0e00, buf, 2);
> + out:
> +	up_read(&mixer->chip->shutdown_rwsem);
> +	if (err < 0)
> +		return err;
> +	mixer->emu0204_ch_switch = value;
> +	return changed;
> +}
> +
> +
> +static struct snd_kcontrol_new snd_emu0204_controls[] = {
> +	{
> +		.iface = SNDRV_CTL_ELEM_IFACE_MIXER,
> +		.name = "Route channels 3/4 to front jack",
> +		.info = snd_emu0204_ch_switch_info,
> +		.get = snd_emu0204_ch_switch_get,
> +		.put = snd_emu0204_ch_switch_put,
> +		.private_value = 0,
> +	},
> +};
> +
> +static int snd_emu0204_controls_create(struct usb_mixer_interface *mixer)
> +{
> +	int i, err;
> +
> +	for (i = 0; i < ARRAY_SIZE(snd_emu0204_controls); ++i) {
> +		err = snd_ctl_add(mixer->chip->card,
> +			snd_ctl_new1(&snd_emu0204_controls[i], mixer));
> +		if (err < 0)
> +			return err;
> +	}
> +	mixer->emu0204_ch_switch = 0; /* Default is 1/2 */
> +
> +	return 0;
> +}
>  /* ASUS Xonar U1 / U3 controls */
>  
>  static int snd_xonar_u1_switch_get(struct snd_kcontrol *kcontrol,
> @@ -1337,6 +1407,13 @@ int snd_usb_mixer_apply_create_quirk(struct usb_mixer_interface *mixer)
>  					      snd_audigy2nx_proc_read);
>  		break;
>  
> +	/* EMU0204 */
> +	case USB_ID(0x041e, 0x3f19):
> +		err = snd_emu0204_controls_create(mixer);
> +		if (err < 0)
> +			break;
> +		break;
> +
>  	case USB_ID(0x0763, 0x2030): /* M-Audio Fast Track C400 */
>  	case USB_ID(0x0763, 0x2031): /* M-Audio Fast Track C400 */
>  		err = snd_c400_create_mixer(mixer);
> -- 
> 1.8.3.2
>