On 22-06-20, 08:28, Pierre-Louis Bossart wrote:
On 6/22/20 1:58 AM, Vinod Koul wrote:
So we had some discussions of the stream states, so I thought it is a good idea to document the state transitions, so add it documentation
Signed-off-by: Vinod Koul vkoul@kernel.org
.../sound/designs/compress-offload.rst | 52 +++++++++++++++++++ 1 file changed, 52 insertions(+)
diff --git a/Documentation/sound/designs/compress-offload.rst b/Documentation/sound/designs/compress-offload.rst index ad4bfbdacc83..6f86db82298b 100644 --- a/Documentation/sound/designs/compress-offload.rst +++ b/Documentation/sound/designs/compress-offload.rst @@ -151,6 +151,58 @@ Modifications include:
- Addition of encoding options when required (derived from OpenMAX IL)
- Addition of rateControlSupported (missing in OpenMAX AL)
+State Machine +=============
+The compressed audio stream state machine is described below ::
+----------+| || OPEN || |+----------+||| compr_set_params()|vcompr_free() +----------+- +-------------------------------------| |
- | | SETUP |
- | +------------------------>| |<---------------------------------+
- | | compr_drain_notify() +----------+ |
- | | | |
- | | | |
- | | | compr_write() |
- | | | |
- | | v |
- | | +----------+ |
- | | | | |
- | | | PREPARE | |
- | | | | |
- | | +----------+ |
- | | | |
- | | | |
- | | | compr_start() |
- | | | |
- | | v |
- | +----------+ +----------+ compr_pause() +----------+ |
- | | | compr_drain() | |---------------->| | |
- | | DRAIN |<-------------------| RUNNING | | PAUSE | |
- | | | | |<----------------| | |
- | +----------+ +----------+ compr_resume() +----------+ |
- | | | | |
- | | | | |
- | | | | |
- | | | | compr_stop() |
- | | | +------------------------------------+
- | | +----------+ |
- | | | | |
- +-----------+------>| |<-------+
compr_free() | FREE | compr_free()| |+----------+Sorry, this confuses me even more...
Oops
a) can you clarify if we can go from running to free directly? is this really a legit transition? There's already the option of doing a stop and a a drain.
As Charles pointed it is legit one, but then from SM we should remove running->free arrow to clarify. Internally, free in running, draining and paused triggers a stop and then free.
b) no way to go back to SETUP from PREPARE? What happens if the app never starts but want to tear down the resources?
See above, free would trigger an internal step to stop (setup) and then freed.
Btw I am not adding changes to code but documenting the 'existing' behaviour, so a code lookup will help
c) no way to stop a paused stream?
Yes missed that, will add.