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| author | Clemens Ladisch <clemens@ladisch.de> | 2014-05-01 12:20:22 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-06-07 13:25:33 -0700 |
| commit | b365350303850369de5352aca05e1dba9da7a9ad (patch) | |
| tree | 6fbce4b9f3b94b06675000935d26262e342cb51c /sound | |
| parent | ce9f1d7670bd1e5e17dcb1fa16f852397d31d6c6 (diff) | |
| download | lwn-b365350303850369de5352aca05e1dba9da7a9ad.tar.gz lwn-b365350303850369de5352aca05e1dba9da7a9ad.zip | |
ALSA: usb-audio: work around corrupted TEAC UD-H01 feedback data
commit 7040b6d1febfdbd9c1595efb751d492cd2503f96 upstream.
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>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'sound')
| -rw-r--r-- | sound/usb/card.h | 1 | ||||
| -rw-r--r-- | sound/usb/endpoint.c | 15 |
2 files changed, 15 insertions, 1 deletions
diff --git a/sound/usb/card.h b/sound/usb/card.h index bf2889a2cae5..82c2d80c8228 100644 --- a/sound/usb/card.h +++ b/sound/usb/card.h @@ -90,6 +90,7 @@ 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 659950e5b94f..308c02b2a597 100644 --- a/sound/usb/endpoint.c +++ b/sound/usb/endpoint.c @@ -467,6 +467,10 @@ 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); @@ -1075,7 +1079,16 @@ 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 |