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@xxxxxxxxxx>
---
.../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()
+ |
+ v
+ compr_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...
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.
b) no way to go back to SETUP from PREPARE? What happens if the app
never starts but want to tear down the resources?
c) no way to stop a paused stream?
