[Problem] In some USB DACs, a terrible pop noise comes to be heard at the start of DSD playback (in the following situations).

- play first DSD track - change from PCM track to DSD track - change from DSD64 track to DSD128 track (and etc...) - seek DSD track - Fast-Forward/Rewind DSD track

[Cause] At the start of playback, there is a little silence. The silence bit pattern "0x69" is required on DSD mode, but it is not like that.

[Solution] This patch adds DSD silence pattern to the endpoint settings.

Signed-off-by: Nobutaka Okabe nob77413@gmail.com --- sound/usb/endpoint.c | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/sound/usb/endpoint.c b/sound/usb/endpoint.c index 57b0d99..a2cdf33 100644 --- a/sound/usb/endpoint.c +++ b/sound/usb/endpoint.c @@ -638,7 +638,21 @@ static int data_ep_set_params(struct snd_usb_endpoint *ep,

ep->datainterval = fmt->datainterval; ep->stride = frame_bits >> 3; - ep->silence_value = pcm_format == SNDRV_PCM_FORMAT_U8 ? 0x80 : 0; + + switch (pcm_format) { + case SNDRV_PCM_FORMAT_U8: + ep->silence_value = 0x80; + break; + case SNDRV_PCM_FORMAT_DSD_U8: + case SNDRV_PCM_FORMAT_DSD_U16_LE: + case SNDRV_PCM_FORMAT_DSD_U32_LE: + case SNDRV_PCM_FORMAT_DSD_U16_BE: + case SNDRV_PCM_FORMAT_DSD_U32_BE: + ep->silence_value = 0x69; + break; + default: + ep->silence_value = 0; + }

/* assume max. frequency is 50% higher than nominal */ ep->freqmax = ep->freqn + (ep->freqn >> 1);