From 8a463225b11047455b374729d18c8a371fe6e591 Mon Sep 17 00:00:00 2001 From: Takashi Iwai Date: Wed, 2 May 2018 10:04:27 +0200 Subject: 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 --- sound/usb/usbaudio.h | 3 +++ 1 file changed, 3 insertions(+) (limited to 'sound/usb/usbaudio.h') diff --git a/sound/usb/usbaudio.h b/sound/usb/usbaudio.h index 4d5c89a7ba2b..32f4a5425536 100644 --- a/sound/usb/usbaudio.h +++ b/sound/usb/usbaudio.h @@ -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 */ }; -- cgit v1.2.1