snd-usb-audio and M-Audio Quattro problems.

[Pavel Polischouk <pavelvp@inbox.ru>]

Hi!

I'm trying to make my Quattro work with ALSA 1.0.13. While this seems 
possible with some hacks, it's not a straightforward and hassle-free 
experience.

I submitted a bug report on the matter some time ago 
(https://bugtrack.alsa-project.org/alsa-bug/view.php?id=2607), see there 
for detailed description. Short description: Quattro initializes itself 
to an unusable (or semi-usable) state and refuses to change its mode 
afterwards.

After seeing no activity on the bug for some time I decided to 
investigate the problem further. First I tried to extend the Audiophile 
hack to Quattro (that disables all altsettings on driver init except the 
one desired). Surprisingly it worked - almost. It only works the first 
time after Quattro has been powered up, after that, re-loading the 
driver doesn't help - the device sticks to the old state.

My temporary patch is available here:
https://bugtrack.alsa-project.org/alsa-bug/file_download.php?file_id=1630&type=bug

Are there any suggestions on how to make the device accept the changing 
settings? Perhaps there's a need for hardware reset or something similar 
between mode changes? Any suggestions/patches are appreciated.

Thanks,
Pavel

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