From: Matias Ezequiel Vara Larsen <mvaralar@redhat.com>
To: virtio-comment@lists.oasis-open.org
Cc: anton.yakovlev@opensynergy.com
Subject: [virtio-comment] [RFC PATCH] virtio-snd: improve PCM command lifecycle description
Date: Wed, 12 Jul 2023 10:37:00 +0200 [thread overview]
Message-ID: <e577462c42778eba4f3fc96cc08038fd6a2b4390.1689090186.git.mvaralar@redhat.com> (raw)
The PCM command lifecycle can be described as a state-machine in which
the switching between states is triggered by commands. This commit
explicitly presents the different states and the commands that are
allowed in a given state. This commit leaves to the implementation the
decision the state reached depending on the command.
Signed-off-by: Matias Ezequiel Vara Larsen <mvaralar@redhat.com>
---
device-types/sound/description.tex | 26 +++++++++++++++++++-------
1 file changed, 19 insertions(+), 7 deletions(-)
diff --git a/device-types/sound/description.tex b/device-types/sound/description.tex
index 54c9c8e..55e93af 100644
--- a/device-types/sound/description.tex
+++ b/device-types/sound/description.tex
@@ -397,9 +397,21 @@ \subsubsection{PCM Control Messages}\label{sec:Device Types / Sound Device / Dev
\item[\field{stream_id}] specifies a PCM stream identifier from 0 to \field{streams} - 1.
\end{description}
-\paragraph{PCM Command Lifecycle}
+\paragraph{PCM Command Lifecycle State Machine}
-A PCM stream has the following command lifecycle:
+A PCM stream can be represented by a state-machine made up of the following
+states:
+\begin{description}
+\item SET PARAMETERS
+\item PREPARE
+\item START
+\item STOP
+\item RELEASE
+\end{description}
+
+A command triggers the transition between these states. To what state to switch
+depends on the implementation. Depending on the state, only certain commands
+are valid. An error may occur if an invalid command is triggered.
\begin{enumerate}
\item SET PARAMETERS
@@ -407,13 +419,13 @@ \subsubsection{PCM Control Messages}\label{sec:Device Types / Sound Device / Dev
The driver negotiates the stream parameters (format, transport, etc) with
the device.
-Possible valid transitions: set parameters, prepare.
+Possible valid commands: set parameters, prepare.
\item PREPARE
The device prepares the stream (allocates resources, etc).
-Possible valid transitions: set parameters, prepare, start, release.
+Possible valid commands: set parameters, prepare, start, release.
\item Output only: the driver transfers data for pre-buffing.
@@ -421,7 +433,7 @@ \subsubsection{PCM Control Messages}\label{sec:Device Types / Sound Device / Dev
The device starts the stream (unmute, putting into running state, etc).
-Possible valid transitions: stop.
+Possible valid commands: stop.
\item The driver transfers data to/from the stream.
@@ -429,13 +441,13 @@ \subsubsection{PCM Control Messages}\label{sec:Device Types / Sound Device / Dev
The device stops the stream (mute, putting into non-running state, etc).
-Possible valid transitions: start, release.
+Possible valid commands: start, release.
\item RELEASE
The device releases the stream (frees resources, etc).
-Possible valid transitions: set parameters, prepare.
+Possible valid commands: set parameters, prepare.
\end{enumerate}
--
2.41.0
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next reply other threads:[~2023-07-12 8:37 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-07-12 8:37 Matias Ezequiel Vara Larsen [this message]
2023-11-07 10:44 ` [virtio-comment] Re: [RFC PATCH] virtio-snd: improve PCM command lifecycle description Matias Ezequiel Vara Larsen
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