Clemens,

please help me out: are you asking me personally to test or is this a general call for the group? If you need me to test, what version of kernel sources do I patch? I am probably not running the latest. Forgive the questions, I do not routinely do these things. Also: Your patch looks quite different from the solution I pointed out. Why? Did you test it yourself? In particular the assertion:

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

•  * by +/- 0x1.0000.
  

is quite different from the assertion "the 3rd byte of the feadback value is getting corrupted and probably changing when it should not " from http://forums.slimdevices.com/showthread.php?93310-Async-USB-Dac-Experiments.... Also, you made it quite explicit for the TEAC UD-H01 but I think it should be more general. I have the Teac A-H01 and it also has the problem. As far as I gather from the various discussions on the Web it probably is a general Tenor 8802 issue. For instance with Nuforce DAC-9 here: http://www.spinics.net/linux/fedora/alsa-user/msg11387.html

Mick

On Mon, 07 Apr 2014 22:09:21 +0200, Clemens Ladisch clemens@ladisch.de wrote:

Please test this patch:

--8<----------------------------------------------------------------->8-- 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: Clemens Ladisch clemens@ladisch.de Tested-by: Mick mick37@gmx.de Cc: stable@vger.kernel.org

---

sound/usb/card.h | 1 + sound/usb/endpoint.c | 15 ++++++++++++++- 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/sound/usb/card.h b/sound/usb/card.h index 9867ab8..97acb90 100644 --- a/sound/usb/card.h +++ b/sound/usb/card.h @@ -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;

diff --git a/sound/usb/endpoint.c b/sound/usb/endpoint.c index e70a87e..7b400eb 100644 --- a/sound/usb/endpoint.c +++ b/sound/usb/endpoint.c @@ -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(ep->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