Hi,
here is a patch set for adding quirks and some new extensions for Dell WD15 dock. The first patch is the resend of the previous post, and the rest are new.
Basically it adds a new "Keep Interface" control for the card to skip resetting the USB interface per stream manipulation. It helps for reducing the long pause before each start of stream on Dell WD15 dock. OTOH, this was confirmed to be harmless on some dock early firmware version, so we can't set it statically in the driver. So, instead, the feature is exposed as a control element so that user can flip dynamically. This feature may be useful for other USB audio devices as well.
Another extension is to allow the quirk entry to override the card longname field. This is needed to give a proper UCM profile. WD15 dock provides two streams, one for the headphone and another for the line out. It's a good example for using a UCM profile.
Takashi
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Takashi Iwai (6): ALSA: usb-audio: Initialize Dell Dock playback volumes ALSA: usb-audio: Avoid superfluous usb_set_interface() calls ALSA: usb-audio: Add keep_iface flag ALSA: usb-audio: Add "Keep Interface" control ALSA: usb-audio: Allow to override the longname string ALSA: usb-audio: Give proper vendor/product name for Dell WD15 Dock
sound/usb/card.c | 146 ++++++++++++++++++++++++++++------------------- sound/usb/mixer.c | 47 +++++++++++++++ sound/usb/mixer_quirks.c | 34 +++++++++++ sound/usb/mixer_quirks.h | 4 ++ sound/usb/pcm.c | 28 ++++----- sound/usb/quirks-table.h | 10 ++++ sound/usb/usbaudio.h | 4 ++ 7 files changed, 200 insertions(+), 73 deletions(-)