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

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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: Clemens 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: Mick <mick37@gmx.de>
Reported-and-tested-by: Andrea Messa <andr.messa@tiscali.it>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Clemens Ladisch 2014-05-01 12:20:22 +02:00 committed by Takashi Iwai
parent 1ee23fe07e
commit 7040b6d1fe
2 changed files with 15 additions and 1 deletions
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1
sound/usb/card.h
View File

@ -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;

15
sound/usb/endpoint.c
View File

@ -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