diff options
| author | Takashi Iwai <tiwai@suse.de> | 2018-05-02 10:04:27 +0200 |
|---|---|---|
| committer | Takashi Iwai <tiwai@suse.de> | 2018-05-02 16:02:33 +0200 |
| commit | 8a463225b11047455b374729d18c8a371fe6e591 (patch) | |
| tree | ad4bfb774497805fc775abf7c64ec7169c2c2919 /sound/usb/pcm.c | |
| parent | b099b9693d23d035c77c218508e083484ff63024 (diff) | |
| download | linux-8a463225b11047455b374729d18c8a371fe6e591.tar.bz2 | |
ALSA: usb-audio: Add keep_iface flag
Introduce a new flag to struct snd_usb_audio for allowing the device
to skip usb_set_interface() calls at changing or closing the stream.
As of this patch, the flag is nowhere set, so it's just a place
holder. The dynamic switching will be added in the following patch.
A background information for this change:
Dell WD15 dock with Realtek chip gives a very long pause at each time
the driver changes the altset, which eventually happens at every PCM
stream open/close and parameter change. As the long pause happens in
each usb_set_interface() call, there is nothing we can do as long as
it's called. The workaround is to reduce calling it as much as
possible, and this flag indicates that behavior.
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Diffstat (limited to 'sound/usb/pcm.c')
| -rw-r--r-- | sound/usb/pcm.c | 17 |
1 files changed, 10 insertions, 7 deletions
diff --git a/sound/usb/pcm.c b/sound/usb/pcm.c index ae7d8a0a0a0a..dc2dfec9effd 100644 --- a/sound/usb/pcm.c +++ b/sound/usb/pcm.c @@ -509,12 +509,14 @@ static int set_format(struct snd_usb_substream *subs, struct audioformat *fmt) /* close the old interface */ if (subs->interface >= 0 && subs->interface != fmt->iface) { - err = usb_set_interface(subs->dev, subs->interface, 0); - if (err < 0) { - dev_err(&dev->dev, - "%d:%d: return to setting 0 failed (%d)\n", - fmt->iface, fmt->altsetting, err); - return -EIO; + if (!subs->stream->chip->keep_iface) { + err = usb_set_interface(subs->dev, subs->interface, 0); + if (err < 0) { + dev_err(&dev->dev, + "%d:%d: return to setting 0 failed (%d)\n", + fmt->iface, fmt->altsetting, err); + return -EIO; + } } subs->interface = -1; subs->altset_idx = 0; @@ -1253,7 +1255,8 @@ static int snd_usb_pcm_close(struct snd_pcm_substream *substream, int direction) stop_endpoints(subs, true); - if (subs->interface >= 0 && + if (!as->chip->keep_iface && + subs->interface >= 0 && !snd_usb_lock_shutdown(subs->stream->chip)) { usb_set_interface(subs->dev, subs->interface, 0); subs->interface = -1; |