The state machine and notes don't accurately explain or allow transitions from STREAM_DEPREPARED and STREAM_DISABLED.
Add more explanations and allow for more transitions as a result of a trigger_stop(), trigger_suspend() and prepare(), depending on the ALSA/ASoC layer behavior defined by the INFO_RESUME and INFO_PAUSE flags.
Also add basic checks to help debug inconsistent states and illegal state machine transitions.
Signed-off-by: Pierre-Louis Bossart pierre-louis.bossart@linux.intel.com --- Documentation/driver-api/soundwire/stream.rst | 61 +++++++++++++------ drivers/soundwire/stream.c | 37 +++++++++++ 2 files changed, 81 insertions(+), 17 deletions(-)
diff --git a/Documentation/driver-api/soundwire/stream.rst b/Documentation/driver-api/soundwire/stream.rst index 5351bd2f34a8..8bceece51554 100644 --- a/Documentation/driver-api/soundwire/stream.rst +++ b/Documentation/driver-api/soundwire/stream.rst @@ -156,22 +156,27 @@ Below shows the SoundWire stream states and state transition diagram. :: +-----------+ +------------+ +----------+ +----------+ | ALLOCATED +---->| CONFIGURED +---->| PREPARED +---->| ENABLED | | STATE | | STATE | | STATE | | STATE | - +-----------+ +------------+ +----------+ +----+-----+ - ^ - | - | - v - +----------+ +------------+ +----+-----+ + +-----------+ +------------+ +---+--+---+ +----+-----+ + ^ ^ ^ + | | | + __| |___________ | + | | | + v | v + +----------+ +-----+------+ +-+--+-----+ | RELEASED |<----------+ DEPREPARED |<-------+ DISABLED | | STATE | | STATE | | STATE | +----------+ +------------+ +----------+
-NOTE: State transition between prepare and deprepare is supported in Spec -but not in the software (subsystem) +NOTE: State transitions between ``SDW_STREAM_ENABLED`` and +``SDW_STREAM_DISABLED`` are only relevant when then INFO_PAUSE flag is +supported at the ALSA/ASoC level. Likewise the transition between +``SDW_DISABLED_STATE`` and ``SDW_PREPARED_STATE`` depends on the +INFO_RESUME flag.
-NOTE2: Stream state transition checks need to be handled by caller -framework, for example ALSA/ASoC. No checks for stream transition exist in -SoundWire subsystem. +NOTE2: The framework implements basic state transition checks, but +does not e.g. check if a transition from DISABLED to ENABLED is valid +on a specific platform. Such tests need to be added at the ALSA/ASoC +level.
Stream State Operations ----------------------- @@ -246,6 +251,9 @@ SDW_STREAM_PREPARED
Prepare state of stream. Operations performed before entering in this state:
+ (0) Steps 1 and 2 are omitted in the case of a resume operation, + where the bus bandwidth is known. + (1) Bus parameters such as bandwidth, frame shape, clock frequency, are computed based on current stream as well as already active stream(s) on Bus. Re-computation is required to accommodate current @@ -270,9 +278,11 @@ Prepare state of stream. Operations performed before entering in this state: After all above operations are successful, stream state is set to ``SDW_STREAM_PREPARED``.
-Bus implements below API for PREPARE state which needs to be called once per -stream. From ASoC DPCM framework, this stream state is linked to -.prepare() operation. +Bus implements below API for PREPARE state which needs to be called +once per stream. From ASoC DPCM framework, this stream state is linked +to .prepare() operation. Since the .trigger() operations may not +follow the .prepare(), a direct transition from +``SDW_STREAM_PREPARED`` to ``SDW_STREAM_DEPREPARED`` is allowed.
.. code-block:: c
@@ -332,6 +342,14 @@ Bus implements below API for DISABLED state which needs to be called once per stream. From ASoC DPCM framework, this stream state is linked to .trigger() stop operation.
+When the INFO_PAUSE flag is supported, a direct transition to +``SDW_STREAM_ENABLED`` is allowed. + +For resume operations where ASoC will use the .prepare() callback, the +stream can transition from ``SDW_STREAM_DISABLED`` to +``SDW_STREAM_PREPARED``, with all required settings restored but +without updating the bandwidth and bit allocation. + .. code-block:: c
int sdw_disable_stream(struct sdw_stream_runtime * stream); @@ -353,9 +371,18 @@ state: After all above operations are successful, stream state is set to ``SDW_STREAM_DEPREPARED``.
-Bus implements below API for DEPREPARED state which needs to be called once -per stream. From ASoC DPCM framework, this stream state is linked to -.trigger() stop operation. +Bus implements below API for DEPREPARED state which needs to be called +once per stream. ALSA/ASoC do not have a concept of 'deprepare', and +the mapping from this stream state to ALSA/ASoC operation may be +implementation specific. + +When the INFO_PAUSE flag is supported, the stream state is linked to +the .hw_free() operation - the stream is not deprepared on a +TRIGGER_STOP. + +Other implementations may transition to the ``SDW_STREAM_DEPREPARED`` +state on TRIGGER_STOP, should they require a transition through the +``SDW_STREAM_PREPARED`` state.
.. code-block:: c
diff --git a/drivers/soundwire/stream.c b/drivers/soundwire/stream.c index 178ae92b8cc1..6aa0b5d370c0 100644 --- a/drivers/soundwire/stream.c +++ b/drivers/soundwire/stream.c @@ -1553,8 +1553,18 @@ int sdw_prepare_stream(struct sdw_stream_runtime *stream)
sdw_acquire_bus_lock(stream);
+ if (stream->state != SDW_STREAM_CONFIGURED && + stream->state != SDW_STREAM_DEPREPARED && + stream->state != SDW_STREAM_DISABLED) { + pr_err("%s: %s: inconsistent state state %d\n", + __func__, stream->name, stream->state); + ret = -EINVAL; + goto state_err; + } + ret = _sdw_prepare_stream(stream);
+state_err: sdw_release_bus_lock(stream); return ret; } @@ -1619,8 +1629,17 @@ int sdw_enable_stream(struct sdw_stream_runtime *stream)
sdw_acquire_bus_lock(stream);
+ if (stream->state != SDW_STREAM_PREPARED && + stream->state != SDW_STREAM_DISABLED) { + pr_err("%s: %s: inconsistent state state %d\n", + __func__, stream->name, stream->state); + ret = -EINVAL; + goto state_err; + } + ret = _sdw_enable_stream(stream);
+state_err: sdw_release_bus_lock(stream); return ret; } @@ -1693,8 +1712,16 @@ int sdw_disable_stream(struct sdw_stream_runtime *stream)
sdw_acquire_bus_lock(stream);
+ if (stream->state != SDW_STREAM_ENABLED) { + pr_err("%s: %s: inconsistent state state %d\n", + __func__, stream->name, stream->state); + ret = -EINVAL; + goto state_err; + } + ret = _sdw_disable_stream(stream);
+state_err: sdw_release_bus_lock(stream); return ret; } @@ -1749,8 +1776,18 @@ int sdw_deprepare_stream(struct sdw_stream_runtime *stream) }
sdw_acquire_bus_lock(stream); + + if (stream->state != SDW_STREAM_PREPARED && + stream->state != SDW_STREAM_DISABLED) { + pr_err("%s: %s: inconsistent state state %d\n", + __func__, stream->name, stream->state); + ret = -EINVAL; + goto state_err; + } + ret = _sdw_deprepare_stream(stream);
+state_err: sdw_release_bus_lock(stream); return ret; }