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authorClemens Ladisch <clemens@ladisch.de>2009-07-13 13:21:58 +0200
committerTakashi Iwai <tiwai@suse.de>2009-07-15 11:55:00 +0200
commit8886f33f25083a47d5fa24ad7b57bb708c5c5403 (patch)
tree6f6e50f07811c01cd7ec469223ba70fb71ae50f6 /sound/usb
parent6847e154e3cd74fca6084124c097980a7634285a (diff)
downloadlinux-8886f33f25083a47d5fa24ad7b57bb708c5c5403.tar.bz2
sound: usb-audio: add workaround for Blue Microphones devices
Blue Microphones USB devices have an alternate setting that sends two channels of data to the computer. Unfortunately, the descriptors of that altsetting have a wrong channel setting, which means that any recorded data from such a device has twice the sample rate from what would be expected. This patch adds a workaround to ignore that altsetting. Since these devices have only one actual channel, no data is lost. Signed-off-by: Clemens Ladisch <clemens@ladisch.de> Cc: <stable@kernel.org> Signed-off-by: Takashi Iwai <tiwai@suse.de>
Diffstat (limited to 'sound/usb')
-rw-r--r--sound/usb/usbaudio.c14
1 files changed, 13 insertions, 1 deletions
diff --git a/sound/usb/usbaudio.c b/sound/usb/usbaudio.c
index c7b902358b7b..44b9cdc8a83b 100644
--- a/sound/usb/usbaudio.c
+++ b/sound/usb/usbaudio.c
@@ -2661,7 +2661,7 @@ static int parse_audio_endpoints(struct snd_usb_audio *chip, int iface_no)
struct usb_interface_descriptor *altsd;
int i, altno, err, stream;
int format;
- struct audioformat *fp;
+ struct audioformat *fp = NULL;
unsigned char *fmt, *csep;
int num;
@@ -2734,6 +2734,18 @@ static int parse_audio_endpoints(struct snd_usb_audio *chip, int iface_no)
continue;
}
+ /*
+ * 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.
+ */
+ if (fmt[4] == 1 && fmt[5] == 2 && altno == 2 && num == 3 &&
+ fp && fp->altsetting == 1 && fp->channels == 1 &&
+ fp->format == SNDRV_PCM_FORMAT_S16_LE &&
+ le16_to_cpu(get_endpoint(alts, 0)->wMaxPacketSize) ==
+ 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)