@@ -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;
@@ -59,6 +59,9 @@ struct snd_usb_audio {
int setup; /* from the 'device_setup' module param */
bool autoclock; /* from the 'autoclock' module param */
+ bool keep_iface; /* keep interface/altset after closing
+ * or parameter change
+ */
struct usb_host_interface *ctrl_intf; /* the audio control interface */
};
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> --- sound/usb/pcm.c | 17 ++++++++++------- sound/usb/usbaudio.h | 3 +++ 2 files changed, 13 insertions(+), 7 deletions(-)