From 8886f33f25083a47d5fa24ad7b57bb708c5c5403 Mon Sep 17 00:00:00 2001 From: Clemens Ladisch Date: Mon, 13 Jul 2009 13:21:58 +0200 Subject: [PATCH] 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 Cc: Signed-off-by: Takashi Iwai --- sound/usb/usbaudio.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) diff --git a/sound/usb/usbaudio.c b/sound/usb/usbaudio.c index c7b902358b7..44b9cdc8a83 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)