[alsa-devel] [PATCH RFC 7/9] ALSA: usb-audio: conditional interface altsetting

[Eldad Zack]

Hi Clemens,

On Mon, 19 Aug 2013, Clemens Ladisch wrote:

> Eldad Zack wrote:
> > On some devices, if the endpoint for the other direction is in use,
> > setting one interface will shutdown the other (in use) endpoint.
> 
> There are (non-UAC) devices where both endpoints are in the same
> interface.

That's good to know. But doesn't setting the alternate the interface on
behalf of one ep while the other ep is in use distrub anything too?
Or did you mean something else?

> 
> > This patch needs revising. It adds a get_interface function, which
> > should not be neccesary (possibly unreliable on some devices?).
> 
> struct usb_interface has cur_altsetting.

Ah, didn't look there. Thanks!

Hmm, so is there a reason why is it also kept in snd_usb_substream 
(altset_idx)?
>From a quick check I see that it is only used in set_format, and using 
iface->cur_altsetting would be the same, so it might be redundant. I'll 
look into that next.

Cheers,
Eldad