ALSA: snd-usb: handle raw data format of UAC2 devices

UAC2 compliant audio devices may announce the capability to transport
raw audio data on their endpoints. Catch this and handle it as
'special' stream on the ALSA side.

Signed-off-by: Daniel Mack <zonque@gmail.com>
Reported-by: Andreas Koch <andreas@akdesigninc.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/include/linux/usb/audio-v2.h b/include/linux/usb/audio-v2.h
index ed13053153f49a2780dc71485dc274330eb8aa6f..c5f2158ab00e48742b0b47d6a18d5e167f50f86b 100644 (file)
--- a/include/linux/usb/audio-v2.h
+++ b/include/linux/usb/audio-v2.h
@@ -170,6 +170,8 @@ struct uac2_as_header_descriptor {
        __u8 iChannelNames;
 } __attribute__((packed));
 
+#define UAC2_FORMAT_TYPE_I_RAW_DATA    (1 << 31)
+
 /* 4.10.1.2 Class-Specific AS Isochronous Audio Data Endpoint Descriptor */
 
 struct uac2_iso_endpoint_descriptor {

diff --git a/sound/usb/format.c b/sound/usb/format.c
index b30d6fb89b406a23b53850f8320a4796da4cc2d3..a695cafc0599cff6f7e5cee5a2062ef239cb9368 100644 (file)
--- a/sound/usb/format.c
+++ b/sound/usb/format.c
@@ -47,7 +47,7 @@ static u64 parse_audio_format_i_type(struct snd_usb_audio *chip,
                                     int protocol)
 {
        int sample_width, sample_bytes;
-       u64 pcm_formats;
+       u64 pcm_formats = 0;
 
        switch (protocol) {
        case UAC_VERSION_1:
@@ -63,14 +63,17 @@ static u64 parse_audio_format_i_type(struct snd_usb_audio *chip,
                struct uac_format_type_i_ext_descriptor *fmt = _fmt;
                sample_width = fmt->bBitResolution;
                sample_bytes = fmt->bSubslotSize;
+
+               if (format & UAC2_FORMAT_TYPE_I_RAW_DATA)
+                       pcm_formats |= SNDRV_PCM_FMTBIT_SPECIAL;
+
                format <<= 1;
                break;
        }
        }
 
-       pcm_formats = 0;
-
-       if (format == 0 || format == (1 << UAC_FORMAT_TYPE_I_UNDEFINED)) {
+       if ((pcm_formats == 0) &&
+           (format == 0 || format == (1 << UAC_FORMAT_TYPE_I_UNDEFINED))) {
                /* some devices don't define this correctly... */
                snd_printdd(KERN_INFO "%d:%u:%d : format type 0 is detected, processed as PCM\n",
                            chip->dev->devnum, fp->iface, fp->altsetting);