[PATCH v4 2/3] ALSA: compress: document the compress gapless audio state machine

[Vinod Koul]

Also documented the galpess transitions. Please note that these are not
really stream states, but show how the stream steps in gapless mode

Signed-off-by: Vinod Koul <vkoul@xxxxxxxxxx>
---
 .../sound/designs/compress-offload.rst        | 32 +++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/Documentation/sound/designs/compress-offload.rst b/Documentation/sound/designs/compress-offload.rst
index b6e9025ae105..82950dbbc4a9 100644
--- a/Documentation/sound/designs/compress-offload.rst
+++ b/Documentation/sound/designs/compress-offload.rst
@@ -250,6 +250,38 @@ Sequence flow for gapless would be:
 
 (note: order for partial_drain and write for next track can be reversed as well)
 
+Gapless Playback SM
+===================
+
+For Gapless, we move from running state to partial drain and back, along
+with setting of meta_data and signalling for next track ::
+
+
+                                        +----------+
+                compr_drain_notify()    |          |
+              +------------------------>|  RUNNING |
+              |                         |          |
+              |                         +----------+
+              |                              |
+              |                              |
+              |                              | compr_next_track()
+              |                              |
+              |                              V
+              |                         +----------+
+              |                         |          |
+              |                         |NEXT_TRACK|
+              |                         |          |
+              |                         +----------+
+              |                              |
+              |                              |
+              |                              | compr_partial_drain()
+              |                              |
+              |                              V
+              |                         +----------+
+              |                         |          |
+              +------------------------ | PARTIAL_ |
+                                        |  DRAIN   |
+                                        +----------+
 
 Not supported
 =============
-- 
2.26.2