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authorGreg Kroah-Hartman <gregkh@linuxfoundation.org>2020-03-23 13:19:00 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2020-03-23 13:19:00 +0100
commit33e12f6e4552b3377ef9076029442282d782eb9e (patch)
treec635c40760ac0ffbe92e2fc16a7ce1dde37a0229 /Documentation/driver-api
parentMerge 5.6-rc7 into char-misc-next (diff)
parentsoundwire: qcom: add support for get_sdw_stream() (diff)
downloadwireguard-linux-33e12f6e4552b3377ef9076029442282d782eb9e.tar.xz
wireguard-linux-33e12f6e4552b3377ef9076029442282d782eb9e.zip
Merge tag 'soundwire-5.7-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/vkoul/soundwire into char-misc-next
Vinod writes: soundwire updates for v5.7-rc1 This contains updates to stream and pm handling in the core as well as updates to Intel drivers for hw sequencing and multi-link. Details: Core: - Updates to stream handling for state machine checks - Changes to handle potential races for probe/enumeration and init of the bus - Add no pm version of read and writes - Support for multiple Slave on same link - Add read_only_wordlength for simple/reduced ports Intel: - Updates to cadence lib to handle hw sequencing - Support for audio dai calls in intel driver - Multi link support for cadence lib Qualcomm: - Support for get_sdw_stream() * tag 'soundwire-5.7-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/vkoul/soundwire: (43 commits) soundwire: qcom: add support for get_sdw_stream() soundwire: stream: Add read_only_wordlength flag to port properties soundwire: cadence: clear FIFO to avoid pop noise issue on playback start soundwire: cadence: multi-link support soundwire: cadence: commit changes in the exit_reset() sequence soundwire: cadence: remove automatic command retries soundwire: cadence: remove PREQ_DELAY assignment soundwire: cadence: enable NORMAL operation in cdns_init() soundwire: cadence: reorder MCP_CONFIG settings soundwire: cadence: make SSP interval programmable soundwire: cadence: move clock/SSP related inits to dedicated function soundwire: cadence: merge routines to clear/set bits soundwire: cadence: mask Slave interrupt before stopping clock soundwire: cadence: fix a io timeout issue in S3 test soundwire: cadence: add clock_stop/restart routines soundwire: cadence: handle error cases with CONFIG_UPDATE soundwire: cadence: add interface to check clock status soundwire: cadence: simplifiy cdns_init() soundwire: cadence: s/update_config/config_update soundwire: stream: use sdw_write instead of update ...
Diffstat (limited to 'Documentation/driver-api')
-rw-r--r--Documentation/driver-api/soundwire/stream.rst61
1 files changed, 44 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