Commit 7040b6d1 authored by Clemens Ladisch's avatar Clemens Ladisch Committed by Takashi Iwai
Browse files

ALSA: usb-audio: work around corrupted TEAC UD-H01 feedback data 



The TEAC UD-H01 firmware sends wrong feedback frequency values, thus
causing the PC to send the samples at a wrong rate, which results in
clicks and crackles in the output.

Add a workaround to detect and fix the corruption.

Signed-off-by: default avatarClemens Ladisch <clemens@ladisch.de>
[mick37@gmx.de: use sender->udh01_fb_quirk rather than
 ep->udh01_fb_quirk in snd_usb_handle_sync_urb()]
Reported-and-tested-by: default avatarMick <mick37@gmx.de>
Reported-and-tested-by: default avatarAndrea Messa <andr.messa@tiscali.it>
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
parent 1ee23fe0

sound/usb/card.h

+1 −0
Original line number Diff line number Diff line
@@ -92,6 +92,7 @@ struct snd_usb_endpoint { 
	unsigned int curframesize;      /* current packet size in frames (for capture) */

	unsigned int syncmaxsize;	/* sync endpoint packet size */

	unsigned int fill_max:1;	/* fill max packet size always */

	unsigned int udh01_fb_quirk:1;	/* corrupted feedback data */

	unsigned int datainterval;      /* log_2 of data packet interval */

	unsigned int syncinterval;	/* P for adaptive mode, 0 otherwise */

	unsigned char silence_value;

sound/usb/endpoint.c

+14 −1
Original line number Diff line number Diff line
@@ -471,6 +471,10 @@ struct snd_usb_endpoint *snd_usb_add_endpoint(struct snd_usb_audio *chip, 
			ep->syncinterval = 3;



		ep->syncmaxsize = le16_to_cpu(get_endpoint(alts, 1)->wMaxPacketSize);



		if (chip->usb_id == USB_ID(0x0644, 0x8038) /* TEAC UD-H01 */ &&

		    ep->syncmaxsize == 4)

			ep->udh01_fb_quirk = 1;

	}



	list_add_tail(&ep->list, &chip->ep_list);
@@ -1105,7 +1109,16 @@ void snd_usb_handle_sync_urb(struct snd_usb_endpoint *ep, 
	if (f == 0)

		return;



	if (unlikely(ep->freqshift == INT_MIN)) {

	if (unlikely(sender->udh01_fb_quirk)) {

		/*

		 * The TEAC UD-H01 firmware sometimes changes the feedback value

		 * by +/- 0x1.0000.

		 */

		if (f < ep->freqn - 0x8000)

			f += 0x10000;

		else if (f > ep->freqn + 0x8000)

			f -= 0x10000;

	} else if (unlikely(ep->freqshift == INT_MIN)) {

		/*

		 * The first time we see a feedback value, determine its format

		 * by shifting it left or right until it matches the nominal

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