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author | Takashi Iwai <tiwai@suse.de> | 2018-05-02 10:04:27 +0200 |
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committer | Takashi Iwai <tiwai@suse.de> | 2018-05-02 16:02:33 +0200 |
commit | 8a463225b11047455b374729d18c8a371fe6e591 (patch) | |
tree | ad4bfb774497805fc775abf7c64ec7169c2c2919 /sound/usb/usbaudio.h | |
parent | ALSA: usb-audio: Avoid superfluous usb_set_interface() calls (diff) | |
download | linux-8a463225b11047455b374729d18c8a371fe6e591.tar.xz linux-8a463225b11047455b374729d18c8a371fe6e591.zip |
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/usbaudio.h')
-rw-r--r-- | sound/usb/usbaudio.h | 3 |
1 files changed, 3 insertions, 0 deletions
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 */ }; |