[alsa-devel] [PATCH 2/2] ALSA: snd-usb: add quirks handler for DSD streams

[Daniel Mack]

On 06.04.2013 13:44, Daniel Mack wrote:
> Unfortunately, none of the UAC standards provides a way to identify DSD
> (Direct Stream Digital) formats. Hence, this patch adds a quirks
> handler to identify USB interfaces that are capable of handling DSD.
> 
> That quirks handler can augment the already parsed formats bit-field,
> typically by any of the new SNDRV_PCM_FMTBIT_DSD_DOP_{U8_U16}, and it
> currently does so for USB devices matching the 'Playback Design'
> vendor id.

Sorry - this identical message got sent twice unintentionally. Please
ignore one of the two ...


Daniel


> Signed-off-by: Daniel Mack <zonque at gmail.com>
> ---
>  sound/usb/format.c |  3 +++
>  sound/usb/quirks.c | 23 +++++++++++++++++++++++
>  sound/usb/quirks.h |  4 ++++
>  3 files changed, 30 insertions(+)
> 
> diff --git a/sound/usb/format.c b/sound/usb/format.c
> index a695caf..a73d67a 100644
> --- a/sound/usb/format.c
> +++ b/sound/usb/format.c
> @@ -136,6 +136,9 @@ static u64 parse_audio_format_i_type(struct snd_usb_audio *chip,
>  		snd_printk(KERN_INFO "%d:%u:%d : unsupported format bits %#x\n",
>  			   chip->dev->devnum, fp->iface, fp->altsetting, format);
>  	}
> +
> +	pcm_formats |= snd_usb_interface_dsd_format_quirks(chip, fp, sample_bytes);
> +
>  	return pcm_formats;
>  }
>  
> diff --git a/sound/usb/quirks.c b/sound/usb/quirks.c
> index a2ac004..2fcc984 100644
> --- a/sound/usb/quirks.c
> +++ b/sound/usb/quirks.c
> @@ -905,3 +905,26 @@ void snd_usb_ctl_msg_quirk(struct usb_device *dev, unsigned int pipe,
>  		mdelay(20);
>  }
>  
> +/*
> + * snd_usb_interface_dsd_format_quirks() is called from format.c to
> + * augment the PCM format bit-field for DSD types. The UAC standards
> + * don't have a designated bit field to denote DSD-capable interfaces,
> + * hence all hardware that is known to support this format has to be
> + * listed here.
> + */
> +u64 snd_usb_interface_dsd_format_quirks(struct snd_usb_audio *chip,
> +					struct audioformat *fp,
> +					unsigned int sample_bytes)
> +{
> +	if ((le16_to_cpu(chip->dev->descriptor.idVendor) == 0x23ba) &&
> +	    fp->altsetting > 1) {
> +		switch (sample_bytes) {
> +		case 1:
> +			return SNDRV_PCM_FMTBIT_DSD_DOP_U8;
> +		case 2:
> +			return SNDRV_PCM_FMTBIT_DSD_DOP_U16;
> +		}
> +	}
> +
> +	return 0;
> +}
> diff --git a/sound/usb/quirks.h b/sound/usb/quirks.h
> index 0ca9e91..f10d00e 100644
> --- a/sound/usb/quirks.h
> +++ b/sound/usb/quirks.h
> @@ -30,4 +30,8 @@ void snd_usb_ctl_msg_quirk(struct usb_device *dev, unsigned int pipe,
>  			   __u8 request, __u8 requesttype, __u16 value,
>  			   __u16 index, void *data, __u16 size);
>  
> +u64 snd_usb_interface_dsd_format_quirks(struct snd_usb_audio *chip,
> +					struct audioformat *fp,
> +					unsigned int sample_bytes);
> +
>  #endif /* __USBAUDIO_QUIRKS_H */
>