kernel-usb-native-dsd-generic-detection.patch

diff -Naur linux.org/sound/usb/card.h linux.new/sound/usb/card.h
--- linux.org/sound/usb/card.h	2018-09-26 17:12:42.000000000 +0200
+++ linux.new/sound/usb/card.h	2018-09-29 20:14:26.029014840 +0200
@@ -32,6 +32,7 @@
 	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 -Naur linux.org/sound/usb/format.c linux.new/sound/usb/format.c
--- linux.org/sound/usb/format.c	2018-09-26 17:12:42.000000000 +0200
+++ linux.new/sound/usb/format.c	2018-09-29 20:14:26.029014840 +0200
@@ -63,8 +63,11 @@
 		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 -Naur linux.org/sound/usb/quirks.c linux.new/sound/usb/quirks.c
--- linux.org/sound/usb/quirks.c	2018-09-26 17:12:42.000000000 +0200
+++ linux.new/sound/usb/quirks.c	2018-09-29 20:15:49.388953011 +0200
@@ -1411,5 +1411,18 @@
 			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 0x20b1:  /* XMOS based devices */
+	case 0x25ce:  /* Mytek devices */
+		if (fp->dsd_raw)
+			return SNDRV_PCM_FMTBIT_DSD_U32_BE;
+		break;
+	default:
+		break;
+
+	}
+
 	return 0;
 }