ALSA: usb: stream: refactor uac3 audio interface parsing

Offload snd_usb_parse_audio_interface() function
which became quite long after adding UAC3 spec support.

Move class-specific parts of uac3 parsing to separate
function which now produce audioformat structure that
is ready to be fed to snd_usb_add_audio_stream().
Signed-off-by: Ruslan Bilovol <ruslan.bilovol@gmail.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/usb/stream.c

@@ -807,122 +807,39 @@ snd_usb_get_audioformat_uac12(struct snd_usb_audio *chip,
 	return fp;
 }
 
-int snd_usb_parse_audio_interface(struct snd_usb_audio *chip, int iface_no)
+static struct audioformat *
+snd_usb_get_audioformat_uac3(struct snd_usb_audio *chip,
+			     struct usb_host_interface *alts,
+			     int iface_no, int altset_idx,
+			     int altno, int stream)
 {
-	struct usb_device *dev;
-	struct usb_interface *iface;
-	struct usb_host_interface *alts;
-	struct usb_interface_descriptor *altsd;
-	struct uac3_as_header_descriptor *as = NULL;
-	int i, altno, err, stream;
-	u64 format = 0;
-	unsigned int num_channels = 0;
-	struct audioformat *fp = NULL;
-	int num, protocol, clock = 0;
-	struct snd_pcm_chmap_elem *chmap_v3 = NULL;
-
-	dev = chip->dev;
-
-	/* parse the interface's altsettings */
-	iface = usb_ifnum_to_if(dev, iface_no);
-
-	num = iface->num_altsetting;
-
-	/*
-	 * Dallas DS4201 workaround: It presents 5 altsettings, but the last
-	 * one misses syncpipe, and does not produce any sound.
-	 */
-	if (chip->usb_id == USB_ID(0x04fa, 0x4201))
-		num = 4;
-
-	for (i = 0; i < num; i++) {
-		alts = &iface->altsetting[i];
-		altsd = get_iface_desc(alts);
-		protocol = altsd->bInterfaceProtocol;
-		/* skip invalid one */
-		if (((altsd->bInterfaceClass != USB_CLASS_AUDIO ||
-		      (altsd->bInterfaceSubClass != USB_SUBCLASS_AUDIOSTREAMING &&
-		       altsd->bInterfaceSubClass != USB_SUBCLASS_VENDOR_SPEC)) &&
-		     altsd->bInterfaceClass != USB_CLASS_VENDOR_SPEC) ||
-		    altsd->bNumEndpoints < 1 ||
-		    le16_to_cpu(get_endpoint(alts, 0)->wMaxPacketSize) == 0)
-			continue;
-		/* must be isochronous */
-		if ((get_endpoint(alts, 0)->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK) !=
-		    USB_ENDPOINT_XFER_ISOC)
-			continue;
-		/* check direction */
-		stream = (get_endpoint(alts, 0)->bEndpointAddress & USB_DIR_IN) ?
-			SNDRV_PCM_STREAM_CAPTURE : SNDRV_PCM_STREAM_PLAYBACK;
-		altno = altsd->bAlternateSetting;
-
-		if (snd_usb_apply_interface_quirk(chip, iface_no, altno))
-			continue;
-
-		/*
-		 * Roland audio streaming interfaces are marked with protocols
-		 * 0/1/2, but are UAC 1 compatible.
-		 */
-		if (USB_ID_VENDOR(chip->usb_id) == 0x0582 &&
-		    altsd->bInterfaceClass == USB_CLASS_VENDOR_SPEC &&
-		    protocol <= 2)
-			protocol = UAC_VERSION_1;
-
-		switch (protocol) {
-		default:
-			dev_dbg(&dev->dev, "%u:%d: unknown interface protocol %#02x, assuming v1\n",
-				iface_no, altno, protocol);
-			protocol = UAC_VERSION_1;
-			/* fall through */
-		case UAC_VERSION_1:
-			/* fall through */
-		case UAC_VERSION_2: {
-			int bm_quirk = 0;
-
-			/*
-			 * Blue Microphones workaround: The last altsetting is
-			 * identical with the previous one, except for a larger
-			 * packet size, but is actually a mislabeled two-channel
-			 * setting; ignore it.
-			 *
-			 * Part 1: prepare quirk flag
-			 */
-			if (altno == 2 && num == 3 &&
-			    fp && fp->altsetting == 1 && fp->channels == 1 &&
-			    fp->formats == SNDRV_PCM_FMTBIT_S16_LE &&
-			    protocol == UAC_VERSION_1 &&
-			    le16_to_cpu(get_endpoint(alts, 0)->wMaxPacketSize) ==
-							fp->maxpacksize * 2)
-				bm_quirk = 1;
-
-			fp = snd_usb_get_audioformat_uac12(chip, alts, protocol,
-							   iface_no, i, altno,
-							   stream, bm_quirk);
-			break;
-		}
-		case UAC_VERSION_3: {
+	struct usb_device *dev = chip->dev;
 	struct uac3_input_terminal_descriptor *input_term;
 	struct uac3_output_terminal_descriptor *output_term;
 	struct uac3_cluster_header_descriptor *cluster;
+	struct uac3_as_header_descriptor *as;
 	struct uac3_hc_descriptor_header hc_header;
+	struct snd_pcm_chmap_elem *chmap;
+	unsigned int num_channels;
+	struct audioformat *fp;
 	u16 cluster_id, wLength;
+	int clock = 0;
+	int err;
 
-			as = snd_usb_find_csint_desc(alts->extra,
-							alts->extralen,
+	as = snd_usb_find_csint_desc(alts->extra, alts->extralen,
 				     NULL, UAC_AS_GENERAL);
-
 	if (!as) {
 		dev_err(&dev->dev,
 			"%u:%d : UAC_AS_GENERAL descriptor not found\n",
 			iface_no, altno);
-				continue;
+		return NULL;
 	}
 
 	if (as->bLength < sizeof(*as)) {
 		dev_err(&dev->dev,
 			"%u:%d : invalid UAC_AS_GENERAL desc\n",
 			iface_no, altno);
-				continue;
+		return NULL;
 	}
 
 	cluster_id = le16_to_cpu(as->wClusterDescrID);
@@ -930,7 +847,7 @@ int snd_usb_parse_audio_interface(struct snd_usb_audio *chip, int iface_no)
 		dev_err(&dev->dev,
 			"%u:%d : no cluster descriptor\n",
 			iface_no, altno);
-				continue;
+		return NULL;
 	}
 
 	/*
@@ -948,12 +865,12 @@ int snd_usb_parse_audio_interface(struct snd_usb_audio *chip, int iface_no)
 			snd_usb_ctrl_intf(chip),
 			&hc_header, sizeof(hc_header));
 	if (err < 0)
-				return err;
+		return ERR_PTR(err);
 	else if (err != sizeof(hc_header)) {
 		dev_err(&dev->dev,
 			"%u:%d : can't get High Capability descriptor\n",
 			iface_no, altno);
-				return -EIO;
+		return ERR_PTR(-EIO);
 	}
 
 	/*
@@ -963,7 +880,7 @@ int snd_usb_parse_audio_interface(struct snd_usb_audio *chip, int iface_no)
 	wLength = le16_to_cpu(hc_header.wLength);
 	cluster = kzalloc(wLength, GFP_KERNEL);
 	if (!cluster)
-				return -ENOMEM;
+		return ERR_PTR(-ENOMEM);
 	err = snd_usb_ctl_msg(chip->dev,
 			usb_rcvctrlpipe(chip->dev, 0),
 			UAC3_CS_REQ_HIGH_CAPABILITY_DESCRIPTOR,
@@ -973,76 +890,162 @@ int snd_usb_parse_audio_interface(struct snd_usb_audio *chip, int iface_no)
 			cluster, wLength);
 	if (err < 0) {
 		kfree(cluster);
-				return err;
+		return ERR_PTR(err);
 	} else if (err != wLength) {
 		dev_err(&dev->dev,
 			"%u:%d : can't get Cluster Descriptor\n",
 			iface_no, altno);
 		kfree(cluster);
-				return -EIO;
+		return ERR_PTR(-EIO);
 	}
 
 	num_channels = cluster->bNrChannels;
-			chmap_v3 = convert_chmap_v3(cluster);
-
+	chmap = convert_chmap_v3(cluster);
 	kfree(cluster);
 
-			format = le64_to_cpu(as->bmFormats);
-
-			/* lookup the terminal associated to this interface
-			 * to extract the clock */
-			input_term = snd_usb_find_input_terminal_descriptor(
-							chip->ctrl_intf,
+	/*
+	 * lookup the terminal associated to this interface
+	 * to extract the clock
+	 */
+	input_term = snd_usb_find_input_terminal_descriptor(chip->ctrl_intf,
 							    as->bTerminalLink);
-
 	if (input_term) {
 		clock = input_term->bCSourceID;
-				break;
+		goto found_clock;
 	}
 
 	output_term = snd_usb_find_output_terminal_descriptor(chip->ctrl_intf,
 							     as->bTerminalLink);
 	if (output_term) {
 		clock = output_term->bCSourceID;
-				break;
+		goto found_clock;
 	}
 
-			dev_err(&dev->dev,
-				"%u:%d : bogus bTerminalLink %d\n",
+	dev_err(&dev->dev, "%u:%d : bogus bTerminalLink %d\n",
 			iface_no, altno, as->bTerminalLink);
-			continue;
-		}
-		}
-
-		if (protocol == UAC_VERSION_1 || protocol == UAC_VERSION_2) {
-			if (!fp)
-				continue;
-			else if (IS_ERR(fp))
-				return PTR_ERR(fp);
-
-			goto skip_uac3;
-		}
+	return NULL;
 
-		fp = audio_format_alloc_init(chip, alts, protocol, iface_no, i,
-					     altno, num_channels, clock);
+found_clock:
+	fp = audio_format_alloc_init(chip, alts, UAC_VERSION_3, iface_no,
+				     altset_idx, altno, num_channels, clock);
 	if (!fp)
-			return -ENOMEM;
+		return ERR_PTR(-ENOMEM);
 
 	fp->attributes = parse_uac_endpoint_attributes(chip, alts,
-							       protocol,
+						       UAC_VERSION_3,
 						       iface_no);
-		fp->chmap = chmap_v3;
+	fp->chmap = chmap;
 
 	/* ok, let's parse further... */
-		if (snd_usb_parse_audio_format_v3(chip, fp, as,
-							stream) < 0) {
+	if (snd_usb_parse_audio_format_v3(chip, fp, as, stream) < 0) {
 		kfree(fp->rate_table);
 		kfree(fp);
-			fp = NULL;
+		return NULL;
+	}
+
+	return fp;
+}
+
+int snd_usb_parse_audio_interface(struct snd_usb_audio *chip, int iface_no)
+{
+	struct usb_device *dev;
+	struct usb_interface *iface;
+	struct usb_host_interface *alts;
+	struct usb_interface_descriptor *altsd;
+	int i, altno, err, stream;
+	struct audioformat *fp = NULL;
+	int num, protocol;
+
+	dev = chip->dev;
+
+	/* parse the interface's altsettings */
+	iface = usb_ifnum_to_if(dev, iface_no);
+
+	num = iface->num_altsetting;
+
+	/*
+	 * Dallas DS4201 workaround: It presents 5 altsettings, but the last
+	 * one misses syncpipe, and does not produce any sound.
+	 */
+	if (chip->usb_id == USB_ID(0x04fa, 0x4201))
+		num = 4;
+
+	for (i = 0; i < num; i++) {
+		alts = &iface->altsetting[i];
+		altsd = get_iface_desc(alts);
+		protocol = altsd->bInterfaceProtocol;
+		/* skip invalid one */
+		if (((altsd->bInterfaceClass != USB_CLASS_AUDIO ||
+		      (altsd->bInterfaceSubClass != USB_SUBCLASS_AUDIOSTREAMING &&
+		       altsd->bInterfaceSubClass != USB_SUBCLASS_VENDOR_SPEC)) &&
+		     altsd->bInterfaceClass != USB_CLASS_VENDOR_SPEC) ||
+		    altsd->bNumEndpoints < 1 ||
+		    le16_to_cpu(get_endpoint(alts, 0)->wMaxPacketSize) == 0)
+			continue;
+		/* must be isochronous */
+		if ((get_endpoint(alts, 0)->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK) !=
+		    USB_ENDPOINT_XFER_ISOC)
 			continue;
+		/* check direction */
+		stream = (get_endpoint(alts, 0)->bEndpointAddress & USB_DIR_IN) ?
+			SNDRV_PCM_STREAM_CAPTURE : SNDRV_PCM_STREAM_PLAYBACK;
+		altno = altsd->bAlternateSetting;
+
+		if (snd_usb_apply_interface_quirk(chip, iface_no, altno))
+			continue;
+
+		/*
+		 * Roland audio streaming interfaces are marked with protocols
+		 * 0/1/2, but are UAC 1 compatible.
+		 */
+		if (USB_ID_VENDOR(chip->usb_id) == 0x0582 &&
+		    altsd->bInterfaceClass == USB_CLASS_VENDOR_SPEC &&
+		    protocol <= 2)
+			protocol = UAC_VERSION_1;
+
+		switch (protocol) {
+		default:
+			dev_dbg(&dev->dev, "%u:%d: unknown interface protocol %#02x, assuming v1\n",
+				iface_no, altno, protocol);
+			protocol = UAC_VERSION_1;
+			/* fall through */
+		case UAC_VERSION_1:
+			/* fall through */
+		case UAC_VERSION_2: {
+			int bm_quirk = 0;
+
+			/*
+			 * Blue Microphones workaround: The last altsetting is
+			 * identical with the previous one, except for a larger
+			 * packet size, but is actually a mislabeled two-channel
+			 * setting; ignore it.
+			 *
+			 * Part 1: prepare quirk flag
+			 */
+			if (altno == 2 && num == 3 &&
+			    fp && fp->altsetting == 1 && fp->channels == 1 &&
+			    fp->formats == SNDRV_PCM_FMTBIT_S16_LE &&
+			    protocol == UAC_VERSION_1 &&
+			    le16_to_cpu(get_endpoint(alts, 0)->wMaxPacketSize) ==
+							fp->maxpacksize * 2)
+				bm_quirk = 1;
+
+			fp = snd_usb_get_audioformat_uac12(chip, alts, protocol,
+							   iface_no, i, altno,
+							   stream, bm_quirk);
+			break;
 		}
+		case UAC_VERSION_3:
+			fp = snd_usb_get_audioformat_uac3(chip, alts,
+						iface_no, i, altno, stream);
+			break;
+		}
+
+		if (!fp)
+			continue;
+		else if (IS_ERR(fp))
+			return PTR_ERR(fp);
 
-skip_uac3:
 		dev_dbg(&dev->dev, "%u:%d: add audio endpoint %#x\n", iface_no, altno, fp->endpoint);
 		err = snd_usb_add_audio_stream(chip, stream, fp);
 		if (err < 0) {