[alsa-devel] [PATCH] New quirk for USB DAC 08bb:2704

[Takashi Iwai]

At Sat, 12 Feb 2011 22:53:25 +0000,
Omari Stephens wrote:
> 
> Howdy, all
> 
> I have one of these:
> http://www.chordelectronics.co.uk/products_detail.asp?id=63
> 
> It's got one of these USB DACs inside
> ID 08bb:2704 Texas Instruments Japan
> 
> The DAC has a single mixer control, Master, which allows you to adjust 
> volume and mute/unmute.  The fun thing is that the volume adjustment has 
> no effect whatsoever.  On machines running pulse, this means that output 
> will be at 0dB pretty much all the time.  (Of course, this is true of 
> non-pulse machines also).
> 
> The attached patch disables the Master control, which causes pulse to 
> control levels entirely in software, as it should for this device.
> 
> The main downside to this patch is that, while the volume part of the 
> Master control is non-functional, the mute/unmute aspect does work as 
> expected.  I couldn't figure out how to change the Master control to 
> just a mute/unmute control, but if someone has suggestions on what to 
> do, that'd be appreciated.  Judging by the comments in the code (and 
> contrary to what I wrote in the map comment), I presume the mute/unmute 
> control is the only reason why 08bb:2702 isn't doing this same thing.

The patch looks good to me.  Could you give your sign-off?


thanks,

Takashi

> 
> Cheers,
> --xsdg
> [2 0001-Add-a-quirk-to-ignore-the-Master-volume-control-on-0.patch <text/x-patch (7bit)>]
> >From 3061b0fa281ea812f0767bc9df6bae7b8016d0d0 Mon Sep 17 00:00:00 2001
> From: Omari Stephens <xsdg at xsdg.org>
> Date: Sat, 12 Feb 2011 20:36:04 +0000
> Subject: [PATCH] Add a quirk to ignore the Master volume control on 08bb:2704
> 
> ---
>  mixer.c      |    6 ++++++
>  mixer_maps.c |   19 ++++++++++++++++++-
>  2 files changed, 24 insertions(+), 1 deletions(-)
> 
> diff --git a/mixer.c b/mixer.c
> index 3ed3901..38d5d77 100644
> --- a/mixer.c
> +++ b/mixer.c
> @@ -1192,6 +1192,12 @@ static int parse_audio_feature_unit(struct mixer_build *state, int unitid, void
>  		/* disable non-functional volume control */
>  		master_bits &= ~UAC_CONTROL_BIT(UAC_FU_VOLUME);
>  		break;
> +	case USB_ID(0x08bb, 0x2704):
> +		snd_printk(KERN_INFO
> +			   "usbmixer: master volume quirk for PCM2704 chip\n");
> +		/* disable non-functional volume control */
> +		master_bits &= ~UAC_CONTROL_BIT(UAC_FU_VOLUME);
> +		break;
>  	}
>  	if (channels > 0)
>  		first_ch_bits = snd_usb_combine_bytes(bmaControls + csize, csize);
> diff --git a/mixer_maps.c b/mixer_maps.c
> index f1324c4..40edd9b 100644
> --- a/mixer_maps.c
> +++ b/mixer_maps.c
> @@ -208,11 +208,23 @@ static struct usbmix_name_map live24ext_map[] = {
>  /* LineX FM Transmitter entry - needed to bypass controls bug */
>  static struct usbmix_name_map linex_map[] = {
>  	/* 1: IT pcm */
> -	/* 2: OT Speaker */ 
> +	/* 2: OT Speaker */
>  	{ 3, "Master" }, /* FU: master volume - left / right / mute */
>  	{ 0 } /* terminator */
>  };
>  
> +/* This DAC (08bb:2704) has a single "Volume" control which isn't actually
> + * connected to anything.  The 08bb:2702 device is based off the LineX map, so
> + * presumably the 2704 one is similar but more broken.
> + */
> +static struct usbmix_name_map ti_broken_usb_dac_map[] = {
> +	/* 1: IT pcm */
> +	/* 2: OT Speaker */
> +	{ 3, NULL }, /* Master (not connected to anything) */
> +	{ 0 }
> +};
> +
> +
>  static struct usbmix_name_map maya44_map[] = {
>  	/* 1: IT line */
>  	{ 2, "Line Playback" }, /* FU */
> @@ -355,6 +367,11 @@ static struct usbmix_ctl_map usbmix_ctl_maps[] = {
>  		.ignore_ctl_error = 1,
>  	},
>  	{
> +		.id = USB_ID(0x08bb, 0x2704),
> +		.map = ti_broken_usb_dac_map,
> +		.ignore_ctl_error = 1,
> +	},
> +	{
>  		.id = USB_ID(0x0a92, 0x0091),
>  		.map = maya44_map,
>  	},
> -- 
> 1.7.2.3
> 
> [3  <text/plain; us-ascii (7bit)>]
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