korg/linux
0
0
Fork 0
mirror of https://mirrors.bfsu.edu.cn/git/linux.git synced 2024-11-11 21:38:32 +08:00
Code Issues Packages Projects Releases Wiki Activity

sound: usb-audio: add workaround for Blue Microphones devices

Browse Source 
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>
This commit is contained in:
Clemens Ladisch 2009-07-13 13:21:58 +02:00 committed by Takashi Iwai
parent 6847e154e3
commit 8886f33f25
1 changed files with 13 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

14
sound/usb/usbaudio.c
View File

@ -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)