ALSA: snd-usb: implement new endpoint streaming model

This patch adds a new generic streaming logic for audio over USB.

It defines a model (snd_usb_endpoint) that handles everything that
is related to an USB endpoint and its streaming. There are functions to
activate and deactivate an endpoint (which call usb_set_interface()),
and to start and stop its URBs. It also has function pointers to be
called when data was received or is about to be sent, and pointer to
a sync slave (another snd_usb_endpoint) that is informed when data has
been received.

A snd_usb_endpoint knows about its state and implements a refcounting,
so only the first user will actually start the URBs and only the last
one to stop it will tear them down again.

With this sort of abstraction, the actual streaming is decoupled from
the pcm handling, which makes the "implicit feedback" mechanisms easy to
implement.

In order to split changes properly, this patch only adds the new
implementation but leaves the old one around, so the the driver doesn't
change its behaviour. The switch to actually use the new code is
submitted separately.

Signed-off-by: Daniel Mack <zonque@gmail.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

path: root/changelog

inotail 0.5

  * Output verbose file headers correctly when used in a pipe
  * Small code cleanups

  -- Tobias Klauser <tklauser@distanz.ch> 2007-09-07 13:30

inotail 0.4

  * Use dynamic buffers of optimal size (st_blksize in struct stat) for
    filesystem I/O (patch by Folkert van Heusden)
  * Added handling of EINTR/EAGAIN while watching files for changes (patch by
    Anthony Martinez)
  * Better error checking and handling (patch by Folkert van Heusden)
  * Various cleanups

  -- Tobias Klauser <tklauser@distanz.ch> 2007-06-20 15:00

inotail 0.3

  * Follow files even if they were moved
  * Fix a problem when tailing more than 4096 bytes/chars at once
  * Only print the filename once when the -v option is specified
  * Various small fixes and cleanups

  -- Tobias Klauser <tklauser@distanz.ch> 2007-04-17 13:44

inotail 0.2

  * Support for the -n/-c +<num> options (tail relative to start of file)
  * Copyright and license cleanup
  * Various fixes

  -- Tobias Klauser <tklauser@distanz.ch.ch> 2006-11-30 17:56