Adding upstream version 6.1.76.upstream/6.1.76upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 527 insertions, 0 deletions

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+=========================
+Audio Stream in SoundWire
+=========================
+
+An audio stream is a logical or virtual connection created between
+
+  (1) System memory buffer(s) and Codec(s)
+
+  (2) DSP memory buffer(s) and Codec(s)
+
+  (3) FIFO(s) and Codec(s)
+
+  (4) Codec(s) and Codec(s)
+
+which is typically driven by a DMA(s) channel through the data link. An
+audio stream contains one or more channels of data. All channels within
+stream must have same sample rate and same sample size.
+
+Assume a stream with two channels (Left & Right) is opened using SoundWire
+interface. Below are some ways a stream can be represented in SoundWire.
+
+Stream Sample in memory (System memory, DSP memory or FIFOs) ::
+
+	-------------------------
+	| L | R | L | R | L | R |
+	-------------------------
+
+Example 1: Stereo Stream with L and R channels is rendered from Master to
+Slave. Both Master and Slave is using single port. ::
+
+	+---------------+                    Clock Signal  +---------------+
+	|    Master     +----------------------------------+     Slave     |
+	|   Interface   |                                  |   Interface   |
+	|               |                                  |       1       |
+	|               |                     Data Signal  |               |
+	|    L  +  R    +----------------------------------+    L  +  R    |
+	|     (Data)    |     Data Direction               |     (Data)    |
+	+---------------+  +----------------------->       +---------------+
+
+
+Example 2: Stereo Stream with L and R channels is captured from Slave to
+Master. Both Master and Slave is using single port. ::
+
+
+	+---------------+                    Clock Signal  +---------------+
+	|    Master     +----------------------------------+     Slave     |
+	|   Interface   |                                  |   Interface   |
+	|               |                                  |       1       |
+	|               |                     Data Signal  |               |
+	|    L  +  R    +----------------------------------+    L  +  R    |
+	|     (Data)    |     Data Direction               |     (Data)    |
+	+---------------+  <-----------------------+       +---------------+
+
+
+Example 3: Stereo Stream with L and R channels is rendered by Master. Each
+of the L and R channel is received by two different Slaves. Master and both
+Slaves are using single port. ::
+
+	+---------------+                    Clock Signal  +---------------+
+	|    Master     +---------+------------------------+     Slave     |
+	|   Interface   |         |                        |   Interface   |
+	|               |         |                        |       1       |
+	|               |         |           Data Signal  |               |
+	|    L  +  R    +---+------------------------------+       L       |
+	|     (Data)    |   |     |    Data Direction      |     (Data)    |
+	+---------------+   |     |   +------------->      +---------------+
+	                    |     |
+	                    |     |
+	                    |     |                        +---------------+
+	                    |     +----------------------> |     Slave     |
+	                    |                              |   Interface   |
+	                    |                              |       2       |
+	                    |                              |               |
+	                    +----------------------------> |       R       |
+	                                                   |     (Data)    |
+	                                                   +---------------+
+
+Example 4: Stereo Stream with L and R channels is rendered by
+Master. Both of the L and R channels are received by two different
+Slaves. Master and both Slaves are using single port handling
+L+R. Each Slave device processes the L + R data locally, typically
+based on static configuration or dynamic orientation, and may drive
+one or more speakers. ::
+
+	+---------------+                    Clock Signal  +---------------+
+	|    Master     +---------+------------------------+     Slave     |
+	|   Interface   |         |                        |   Interface   |
+	|               |         |                        |       1       |
+	|               |         |           Data Signal  |               |
+	|    L  +  R    +---+------------------------------+     L + R     |
+	|     (Data)    |   |     |    Data Direction      |     (Data)    |
+	+---------------+   |     |   +------------->      +---------------+
+	                    |     |
+	                    |     |
+	                    |     |                        +---------------+
+	                    |     +----------------------> |     Slave     |
+	                    |                              |   Interface   |
+	                    |                              |       2       |
+	                    |                              |               |
+	                    +----------------------------> |     L + R     |
+	                                                   |     (Data)    |
+	                                                   +---------------+
+
+Example 5: Stereo Stream with L and R channel is rendered by two different
+Ports of the Master and is received by only single Port of the Slave
+interface. ::
+
+	+--------------------+
+	|                    |
+	|     +--------------+                             +----------------+
+	|     |             ||                             |                |
+	|     |  Data Port  ||  L Channel                  |                |
+	|     |      1      |------------+                 |                |
+	|     |  L Channel  ||           |                 +-----+----+     |
+	|     |   (Data)    ||           |   L + R Channel ||    Data |     |
+	| Master  +----------+           | +---+---------> ||    Port |     |
+	| Interface          |           |                 ||     1   |     |
+	|     +--------------+           |                 ||         |     |
+	|     |             ||           |                 +----------+     |
+	|     |  Data Port  |------------+                 |                |
+	|     |      2      ||  R Channel                  |     Slave      |
+	|     |  R Channel  ||                             |   Interface    |
+	|     |   (Data)    ||                             |       1        |
+	|     +--------------+         Clock Signal        |     L  +  R    |
+	|                    +---------------------------> |      (Data)    |
+	+--------------------+                             |                |
+							   +----------------+
+
+Example 6: Stereo Stream with L and R channel is rendered by 2 Masters, each
+rendering one channel, and is received by two different Slaves, each
+receiving one channel. Both Masters and both Slaves are using single port. ::
+
+	+---------------+                    Clock Signal  +---------------+
+	|    Master     +----------------------------------+     Slave     |
+	|   Interface   |                                  |   Interface   |
+	|       1       |                                  |       1       |
+	|               |                     Data Signal  |               |
+	|       L       +----------------------------------+       L       |
+	|     (Data)    |     Data Direction               |     (Data)    |
+	+---------------+  +----------------------->       +---------------+
+
+	+---------------+                    Clock Signal  +---------------+
+	|    Master     +----------------------------------+     Slave     |
+	|   Interface   |                                  |   Interface   |
+	|       2       |                                  |       2       |
+	|               |                     Data Signal  |               |
+	|       R       +----------------------------------+       R       |
+	|     (Data)    |     Data Direction               |     (Data)    |
+	+---------------+  +----------------------->       +---------------+
+
+Example 7: Stereo Stream with L and R channel is rendered by 2
+Masters, each rendering both channels. Each Slave receives L + R. This
+is the same application as Example 4 but with Slaves placed on
+separate links. ::
+
+	+---------------+                    Clock Signal  +---------------+
+	|    Master     +----------------------------------+     Slave     |
+	|   Interface   |                                  |   Interface   |
+	|       1       |                                  |       1       |
+	|               |                     Data Signal  |               |
+	|     L + R     +----------------------------------+     L + R     |
+	|     (Data)    |     Data Direction               |     (Data)    |
+	+---------------+  +----------------------->       +---------------+
+
+	+---------------+                    Clock Signal  +---------------+
+	|    Master     +----------------------------------+     Slave     |
+	|   Interface   |                                  |   Interface   |
+	|       2       |                                  |       2       |
+	|               |                     Data Signal  |               |
+	|     L + R     +----------------------------------+     L + R     |
+	|     (Data)    |     Data Direction               |     (Data)    |
+	+---------------+  +----------------------->       +---------------+
+
+Example 8: 4-channel Stream is rendered by 2 Masters, each rendering a
+2 channels. Each Slave receives 2 channels. ::
+
+	+---------------+                    Clock Signal  +---------------+
+	|    Master     +----------------------------------+     Slave     |
+	|   Interface   |                                  |   Interface   |
+	|       1       |                                  |       1       |
+	|               |                     Data Signal  |               |
+	|    L1 + R1    +----------------------------------+    L1 + R1    |
+	|     (Data)    |     Data Direction               |     (Data)    |
+	+---------------+  +----------------------->       +---------------+
+
+	+---------------+                    Clock Signal  +---------------+
+	|    Master     +----------------------------------+     Slave     |
+	|   Interface   |                                  |   Interface   |
+	|       2       |                                  |       2       |
+	|               |                     Data Signal  |               |
+	|     L2 + R2   +----------------------------------+    L2 + R2    |
+	|     (Data)    |     Data Direction               |     (Data)    |
+	+---------------+  +----------------------->       +---------------+
+
+Note1: In multi-link cases like above, to lock, one would acquire a global
+lock and then go on locking bus instances. But, in this case the caller
+framework(ASoC DPCM) guarantees that stream operations on a card are
+always serialized. So, there is no race condition and hence no need for
+global lock.
+
+Note2: A Slave device may be configured to receive all channels
+transmitted on a link for a given Stream (Example 4) or just a subset
+of the data (Example 3). The configuration of the Slave device is not
+handled by a SoundWire subsystem API, but instead by the
+snd_soc_dai_set_tdm_slot() API. The platform or machine driver will
+typically configure which of the slots are used. For Example 4, the
+same slots would be used by all Devices, while for Example 3 the Slave
+Device1 would use e.g. Slot 0 and Slave device2 slot 1.
+
+Note3: Multiple Sink ports can extract the same information for the
+same bitSlots in the SoundWire frame, however multiple Source ports
+shall be configured with different bitSlot configurations. This is the
+same limitation as with I2S/PCM TDM usages.
+
+SoundWire Stream Management flow
+================================
+
+Stream definitions
+------------------
+
+  (1) Current stream: This is classified as the stream on which operation has
+      to be performed like prepare, enable, disable, de-prepare etc.
+
+  (2) Active stream: This is classified as the stream which is already active
+      on Bus other than current stream. There can be multiple active streams
+      on the Bus.
+
+SoundWire Bus manages stream operations for each stream getting
+rendered/captured on the SoundWire Bus. This section explains Bus operations
+done for each of the stream allocated/released on Bus. Following are the
+stream states maintained by the Bus for each of the audio stream.
+
+
+SoundWire stream states
+-----------------------
+
+Below shows the SoundWire stream states and state transition diagram. ::
+
+	+-----------+     +------------+     +----------+     +----------+
+	| ALLOCATED +---->| CONFIGURED +---->| PREPARED +---->| ENABLED  |
+	|   STATE   |     |    STATE   |     |  STATE   |     |  STATE   |
+	+-----------+     +------------+     +---+--+---+     +----+-----+
+	                                         ^  ^              ^
+				                 |  |              |
+				               __|  |___________   |
+				              |                 |  |
+	                                      v                 |  v
+	         +----------+           +-----+------+        +-+--+-----+
+	         | RELEASED |<----------+ DEPREPARED |<-------+ DISABLED |
+	         |  STATE   |           |   STATE    |        |  STATE   |
+	         +----------+           +------------+        +----------+
+
+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: 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
+-----------------------
+
+Below section explains the operations done by the Bus on Master(s) and
+Slave(s) as part of stream state transitions.
+
+SDW_STREAM_ALLOCATED
+~~~~~~~~~~~~~~~~~~~~
+
+Allocation state for stream. This is the entry state
+of the stream. Operations performed before entering in this state:
+
+  (1) A stream runtime is allocated for the stream. This stream
+      runtime is used as a reference for all the operations performed
+      on the stream.
+
+  (2) The resources required for holding stream runtime information are
+      allocated and initialized. This holds all stream related information
+      such as stream type (PCM/PDM) and parameters, Master and Slave
+      interface associated with the stream, stream state etc.
+
+After all above operations are successful, stream state is set to
+``SDW_STREAM_ALLOCATED``.
+
+Bus implements below API for allocate a stream which needs to be called once
+per stream. From ASoC DPCM framework, this stream state maybe linked to
+.startup() operation.
+
+.. code-block:: c
+
+  int sdw_alloc_stream(char * stream_name);
+
+The SoundWire core provides a sdw_startup_stream() helper function,
+typically called during a dailink .startup() callback, which performs
+stream allocation and sets the stream pointer for all DAIs
+connected to a stream.
+
+SDW_STREAM_CONFIGURED
+~~~~~~~~~~~~~~~~~~~~~
+
+Configuration state of stream. Operations performed before entering in
+this state:
+
+  (1) The resources allocated for stream information in SDW_STREAM_ALLOCATED
+      state are updated here. This includes stream parameters, Master(s)
+      and Slave(s) runtime information associated with current stream.
+
+  (2) All the Master(s) and Slave(s) associated with current stream provide
+      the port information to Bus which includes port numbers allocated by
+      Master(s) and Slave(s) for current stream and their channel mask.
+
+After all above operations are successful, stream state is set to
+``SDW_STREAM_CONFIGURED``.
+
+Bus implements below APIs for CONFIG state which needs to be called by
+the respective Master(s) and Slave(s) associated with stream. These APIs can
+only be invoked once by respective Master(s) and Slave(s). From ASoC DPCM
+framework, this stream state is linked to .hw_params() operation.
+
+.. code-block:: c
+
+  int sdw_stream_add_master(struct sdw_bus * bus,
+		struct sdw_stream_config * stream_config,
+		struct sdw_ports_config * ports_config,
+		struct sdw_stream_runtime * stream);
+
+  int sdw_stream_add_slave(struct sdw_slave * slave,
+		struct sdw_stream_config * stream_config,
+		struct sdw_ports_config * ports_config,
+		struct sdw_stream_runtime * stream);
+
+
+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
+      stream on the Bus.
+
+  (2) Transport and port parameters of all Master(s) and Slave(s) port(s) are
+      computed for the current as well as already active stream based on frame
+      shape and clock frequency computed in step 1.
+
+  (3) Computed Bus and transport parameters are programmed in Master(s) and
+      Slave(s) registers. The banked registers programming is done on the
+      alternate bank (bank currently unused). Port(s) are enabled for the
+      already active stream(s) on the alternate bank (bank currently unused).
+      This is done in order to not disrupt already active stream(s).
+
+  (4) Once all the values are programmed, Bus initiates switch to alternate
+      bank where all new values programmed gets into effect.
+
+  (5) Ports of Master(s) and Slave(s) for current stream are prepared by
+      programming PrepareCtrl register.
+
+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. 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
+
+  int sdw_prepare_stream(struct sdw_stream_runtime * stream);
+
+
+SDW_STREAM_ENABLED
+~~~~~~~~~~~~~~~~~~
+
+Enable state of stream. The data port(s) are enabled upon entering this state.
+Operations performed before entering in this state:
+
+  (1) All the values computed in SDW_STREAM_PREPARED state are programmed
+      in alternate bank (bank currently unused). It includes programming of
+      already active stream(s) as well.
+
+  (2) All the Master(s) and Slave(s) port(s) for the current stream are
+      enabled on alternate bank (bank currently unused) by programming
+      ChannelEn register.
+
+  (3) Once all the values are programmed, Bus initiates switch to alternate
+      bank where all new values programmed gets into effect and port(s)
+      associated with current stream are enabled.
+
+After all above operations are successful, stream state is set to
+``SDW_STREAM_ENABLED``.
+
+Bus implements below API for ENABLE state which needs to be called once per
+stream. From ASoC DPCM framework, this stream state is linked to
+.trigger() start operation.
+
+.. code-block:: c
+
+  int sdw_enable_stream(struct sdw_stream_runtime * stream);
+
+SDW_STREAM_DISABLED
+~~~~~~~~~~~~~~~~~~~
+
+Disable state of stream. The data port(s) are disabled upon exiting this state.
+Operations performed before entering in this state:
+
+  (1) All the Master(s) and Slave(s) port(s) for the current stream are
+      disabled on alternate bank (bank currently unused) by programming
+      ChannelEn register.
+
+  (2) All the current configuration of Bus and active stream(s) are programmed
+      into alternate bank (bank currently unused).
+
+  (3) Once all the values are programmed, Bus initiates switch to alternate
+      bank where all new values programmed gets into effect and port(s) associated
+      with current stream are disabled.
+
+After all above operations are successful, stream state is set to
+``SDW_STREAM_DISABLED``.
+
+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);
+
+
+SDW_STREAM_DEPREPARED
+~~~~~~~~~~~~~~~~~~~~~
+
+De-prepare state of stream. Operations performed before entering in this
+state:
+
+  (1) All the port(s) of Master(s) and Slave(s) for current stream are
+      de-prepared by programming PrepareCtrl register.
+
+  (2) The payload bandwidth of current stream is reduced from the total
+      bandwidth requirement of bus and new parameters calculated and
+      applied by performing bank switch etc.
+
+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. 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
+
+  int sdw_deprepare_stream(struct sdw_stream_runtime * stream);
+
+
+SDW_STREAM_RELEASED
+~~~~~~~~~~~~~~~~~~~
+
+Release state of stream. Operations performed before entering in this state:
+
+  (1) Release port resources for all Master(s) and Slave(s) port(s)
+      associated with current stream.
+
+  (2) Release Master(s) and Slave(s) runtime resources associated with
+      current stream.
+
+  (3) Release stream runtime resources associated with current stream.
+
+After all above operations are successful, stream state is set to
+``SDW_STREAM_RELEASED``.
+
+Bus implements below APIs for RELEASE state which needs to be called by
+all the Master(s) and Slave(s) associated with stream. From ASoC DPCM
+framework, this stream state is linked to .hw_free() operation.
+
+.. code-block:: c
+
+  int sdw_stream_remove_master(struct sdw_bus * bus,
+		struct sdw_stream_runtime * stream);
+  int sdw_stream_remove_slave(struct sdw_slave * slave,
+		struct sdw_stream_runtime * stream);
+
+
+The .shutdown() ASoC DPCM operation calls below Bus API to release
+stream assigned as part of ALLOCATED state.
+
+In .shutdown() the data structure maintaining stream state are freed up.
+
+.. code-block:: c
+
+  void sdw_release_stream(struct sdw_stream_runtime * stream);
+
+The SoundWire core provides a sdw_shutdown_stream() helper function,
+typically called during a dailink .shutdown() callback, which clears
+the stream pointer for all DAIS connected to a stream and releases the
+memory allocated for the stream.
+
+Not Supported
+=============
+
+1. A single port with multiple channels supported cannot be used between two
+   streams or across stream. For example a port with 4 channels cannot be used
+   to handle 2 independent stereo streams even though it's possible in theory
+   in SoundWire.