On Mon, 19 Mar 2018 08:22:19 +0100, Oleksandr Andrushchenko wrote:
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
- add XENSND_OP_HW_PARAM_QUERY request to read/update stream configuration space: request passes desired intervals/formats for the stream parameters and the response returns allowed intervals and formats mask that can be used.
Changes since v2:
- Konrad's r-b tag for version patch
- MAJOR: changed req/resp/evt packet sizes from 32 to 64 octets
- Reworked XENSND_OP_HW_PARAM_QUERY so it now sends all parameters at once, allowing to check all the configuration space.
- Minor documentation cleanup (added missed "reserved" fields)
Changes since v1:
- 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.
- 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
I can't judge exactly about the protocol without the actual FE/BE implementations, but the change looks good to me, especially if you've already tested something.
If other people have no concern, let's go ahead with FE/BE stuff.
thanks,
Takashi