[Xen-devel][PATCH v2 0/3] sndif: add explicit back and front synchronization

[Oleksandr Andrushchenko <andr2000@gmail.com>]

From: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>

Hello, all!

In order to provide explicit synchronization between backend and
frontend the following changes are introduced in the protocol:
 - bump protocol version to 2
 - add new ring buffer for sending asynchronous events from
   backend to frontend to report number of bytes played by the
   frontend (XENSND_EVT_CUR_POS)
 - introduce trigger events for playback control: start/stop/pause/resume
 - add "req-" prefix to event-channel and ring-ref to unify naming
   of the Xen event channels for requests and events


Changes since v1:

1. Changed protocol version definition from string to integer,
so it can easily be used in comparisons.
Konrad, I have removed your r-b tag for the reason of this change.

2. In order to provide explicit stream parameter negotiation between
backend and frontend the following changes are introduced in the protocol:
add XENSND_OP_HW_PARAM_QUERY request to read/update
configuration space for the parameter given: request passes
desired parameter interval (mask) and the response to this request
returns min/max interval (mask) for the parameter to be used.

Parameters supported by this request/response:
 - format mask
 - sample rate interval
 - number of channels interval
 - buffer size, interval, frames
 - period size, interval, frames

Thank you,
Oleksandr Andrushchenko

Oleksandr Andrushchenko (3):
  sndif: Introduce protocol version
  sndif: Add explicit back and front synchronization
  sndif: Add explicit back and front parameter negotiation

 xen/include/public/io/sndif.h | 295 ++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 286 insertions(+), 9 deletions(-)

-- 
2.7.4