| From 8886f33f25083a47d5fa24ad7b57bb708c5c5403 Mon Sep 17 00:00:00 2001 |
| From: Clemens Ladisch <clemens@ladisch.de> |
| Date: Mon, 13 Jul 2009 13:21:58 +0200 |
| Subject: sound: usb-audio: add workaround for Blue Microphones devices |
| |
| From: Clemens Ladisch <clemens@ladisch.de> |
| |
| commit 8886f33f25083a47d5fa24ad7b57bb708c5c5403 upstream. |
| |
| 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> |
| Signed-off-by: Takashi Iwai <tiwai@suse.de> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de> |
| |
| --- |
| sound/usb/usbaudio.c | 14 +++++++++++++- |
| 1 file changed, 13 insertions(+), 1 deletion(-) |
| |
| --- a/sound/usb/usbaudio.c |
| +++ b/sound/usb/usbaudio.c |
| @@ -2649,7 +2649,7 @@ static int parse_audio_endpoints(struct |
| 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; |
| |
| @@ -2722,6 +2722,18 @@ static int parse_audio_endpoints(struct |
| 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) |
