ALSA: usb-audio: Add native DSD support for Mytek DACs

Add new mostly generic code with Mytek VID to support native DSD mode.

This implementation should be easier to maintain when manufacturers
release new products.

Signed-off-by: Jussi Laako <jussi@sonarnerd.net>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/sound/usb/card.h b/sound/usb/card.h
index 1406292d50ece6d9b0da7dba51e7252176ac61d1..9b41b7dda84fafff418d357590efadd5c2763ca7 100644 (file)
--- a/sound/usb/card.h
+++ b/sound/usb/card.h
@@ -32,6 +32,7 @@ struct audioformat {
        struct snd_pcm_chmap_elem *chmap; /* (optional) channel map */
        bool dsd_dop;                   /* add DOP headers in case of DSD samples */
        bool dsd_bitrev;                /* reverse the bits of each DSD sample */
+       bool dsd_raw;                   /* altsetting is raw DSD */
 };
 
 struct snd_usb_substream;

diff --git a/sound/usb/format.c b/sound/usb/format.c
index 49e7ec6d2399072c456f5f7975a5a2a22a5bf94a..0a2a27f2854d169a09ea658930917435e0f97836 100644 (file)
--- a/sound/usb/format.c
+++ b/sound/usb/format.c
@@ -64,8 +64,11 @@ static u64 parse_audio_format_i_type(struct snd_usb_audio *chip,
                sample_width = fmt->bBitResolution;
                sample_bytes = fmt->bSubslotSize;
 
-               if (format & UAC2_FORMAT_TYPE_I_RAW_DATA)
+               if (format & UAC2_FORMAT_TYPE_I_RAW_DATA) {
                        pcm_formats |= SNDRV_PCM_FMTBIT_SPECIAL;
+                       /* flag potentially raw DSD capable altsettings */
+                       fp->dsd_raw = true;
+               }
 
                format <<= 1;
                break;

diff --git a/sound/usb/quirks.c b/sound/usb/quirks.c
index f4b69173682ccddc8c5f3cfb4d5931c52bc11116..c616c251dbacc0a98c48c65cc19c2aec62ae3a15 100644 (file)
--- a/sound/usb/quirks.c
+++ b/sound/usb/quirks.c
@@ -1443,6 +1443,19 @@ u64 snd_usb_interface_dsd_format_quirks(struct snd_usb_audio *chip,
                        return SNDRV_PCM_FMTBIT_DSD_U32_BE;
        }
 
+       /* Mostly generic method to detect many DSD-capable implementations -
+        * from XMOS/Thesycon
+        */
+       switch (USB_ID_VENDOR(chip->usb_id)) {
+       case 0x25ce:  /* Mytek devices */
+               if (fp->dsd_raw)
+                       return SNDRV_PCM_FMTBIT_DSD_U32_BE;
+               break;
+       default:
+               break;
+
+       }
+
        return 0;
 }