2 files changed, 58 insertions, 13 deletions

diff --git a/include/linux/usb/audio-v2.h b/include/linux/usb/audio-v2.h
index 2389f93a28b5..92f1d99f0f17 100644
--- a/include/linux/usb/audio-v2.h
+++ b/include/linux/usb/audio-v2.h
@@ -105,6 +105,22 @@ struct uac_as_header_descriptor_v2 {
         __u8 iChannelNames;
 } __attribute__((packed));
 
+/* 4.10.1.2 Class-Specific AS Isochronous Audio Data Endpoint Descriptor */
+
+struct uac2_iso_endpoint_descriptor {
+        __u8  bLength;                  /* in bytes: 8 */
+        __u8  bDescriptorType;          /* USB_DT_CS_ENDPOINT */
+        __u8  bDescriptorSubtype;       /* EP_GENERAL */
+        __u8  bmAttributes;
+        __u8  bmControls;
+        __u8  bLockDelayUnits;
+        __le16 wLockDelay;
+} __attribute__((packed));
+
+#define UAC2_CONTROL_PITCH              (3 << 0)
+#define UAC2_CONTROL_DATA_OVERRUN       (3 << 2)
+#define UAC2_CONTROL_DATA_UNDERRUN      (3 << 4)
+
 /* 6.1 Interrupt Data Message */
 
 #define UAC2_INTERRUPT_DATA_MSG_VENDOR  (1 << 0)
diff --git a/sound/usb/endpoint.c b/sound/usb/endpoint.c
index 4887342cae27..28ee1ce3971a 100644
--- a/sound/usb/endpoint.c
+++ b/sound/usb/endpoint.c
@@ -149,6 +149,47 @@ int snd_usb_add_audio_endpoint(struct snd_usb_audio *chip, int stream, struct au
         return 0;
 }
 
+static int parse_uac_endpoint_attributes(struct snd_usb_audio *chip,
+                                         struct usb_host_interface *alts,
+                                         int protocol, int iface_no)
+{
+        /* parsed with a v1 header here. that's ok as we only look at the
+         * header first which is the same for both versions */
+        struct uac_iso_endpoint_descriptor *csep;
+        struct usb_interface_descriptor *altsd = get_iface_desc(alts);
+        int attributes = 0;
+
+        csep = snd_usb_find_desc(alts->endpoint[0].extra, alts->endpoint[0].extralen, NULL, USB_DT_CS_ENDPOINT);
+
+        /* Creamware Noah has this descriptor after the 2nd endpoint */
+        if (!csep && altsd->bNumEndpoints >= 2)
+                csep = snd_usb_find_desc(alts->endpoint[1].extra, alts->endpoint[1].extralen, NULL, USB_DT_CS_ENDPOINT);
+
+        if (!csep || csep->bLength < 7 ||
+            csep->bDescriptorSubtype != UAC_EP_GENERAL) {
+                snd_printk(KERN_WARNING "%d:%u:%d : no or invalid"
+                           " class specific endpoint descriptor\n",
+                           chip->dev->devnum, iface_no,
+                           altsd->bAlternateSetting);
+                return 0;
+        }
+
+        if (protocol == UAC_VERSION_1) {
+                attributes = csep->bmAttributes;
+        } else {
+                struct uac2_iso_endpoint_descriptor *csep2 =
+                        (struct uac2_iso_endpoint_descriptor *) csep;
+
+                attributes = csep->bmAttributes & UAC_EP_CS_ATTR_FILL_MAX;
+
+                /* emulate the endpoint attributes of a v1 device */
+                if (csep2->bmControls & UAC2_CONTROL_PITCH)
+                        attributes |= UAC_EP_CS_ATTR_PITCH_CONTROL;
+        }
+
+        return attributes;
+}
+
 int snd_usb_parse_audio_endpoints(struct snd_usb_audio *chip, int iface_no)
 {
         struct usb_device *dev;
@@ -158,7 +199,6 @@ int snd_usb_parse_audio_endpoints(struct snd_usb_audio *chip, int iface_no)
         int i, altno, err, stream;
         int format = 0, num_channels = 0;
         struct audioformat *fp = NULL;
-        unsigned char *csep;
         int num, protocol;
         struct uac_format_type_i_continuous_descriptor *fmt;
 
@@ -279,17 +319,6 @@ int snd_usb_parse_audio_endpoints(struct snd_usb_audio *chip, int iface_no)
                                                         fp->maxpacksize * 2)
                         continue;
 
-                csep = snd_usb_find_desc(alts->endpoint[0].extra, alts->endpoint[0].extralen, NULL, USB_DT_CS_ENDPOINT);
-                /* Creamware Noah has this descriptor after the 2nd endpoint */
-                if (!csep && altsd->bNumEndpoints >= 2)
-                        csep = snd_usb_find_desc(alts->endpoint[1].extra, alts->endpoint[1].extralen, NULL, USB_DT_CS_ENDPOINT);
-                if (!csep || csep[0] < 7 || csep[2] != UAC_EP_GENERAL) {
-                        snd_printk(KERN_WARNING "%d:%u:%d : no or invalid"
-                                   " class specific endpoint descriptor\n",
-                                   dev->devnum, iface_no, altno);
-                        csep = NULL;
-                }
-
                 fp = kzalloc(sizeof(*fp), GFP_KERNEL);
                 if (! fp) {
                         snd_printk(KERN_ERR "cannot malloc\n");
@@ -308,7 +337,7 @@ int snd_usb_parse_audio_endpoints(struct snd_usb_audio *chip, int iface_no)
                 if (snd_usb_get_speed(dev) == USB_SPEED_HIGH)
                         fp->maxpacksize = (((fp->maxpacksize >> 11) & 3) + 1)
                                         * (fp->maxpacksize & 0x7ff);
-                fp->attributes = csep ? csep[3] : 0;
+                fp->attributes = parse_uac_endpoint_attributes(chip, alts, protocol, iface_no);
 
                 /* some quirks for attributes here */