Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 8886f33f authored by Clemens Ladisch's avatar Clemens Ladisch Committed by Takashi Iwai
Browse files

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: default avatarClemens Ladisch <clemens@ladisch.de>
Cc: <stable@kernel.org>
Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
parent 6847e154

sound/usb/usbaudio.c

+13 −1
Original line number Diff line number Diff line
@@ -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)