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author | Linus Torvalds <torvalds@linux-foundation.org> | 2020-04-03 13:22:40 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2020-04-03 13:22:40 -0700 |
commit | 0ad5b053d438990fabaa324499abb6131b9d2202 (patch) | |
tree | aaabca2e4d66d0b6572324f4a71017ecec4fa022 /Documentation/driver-api | |
parent | ff2ae607c6f329d11a3b0528801ea7474be8c3e9 (diff) | |
parent | 885a64715fd81e6af6d94a038556e0b2e6deb19c (diff) |
Merge tag 'char-misc-5.7-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc
Pull char/misc driver updates from Greg KH:
"Here is the big set of char/misc/other driver patches for 5.7-rc1.
Lots of things in here, and it's later than expected due to some
reverts to resolve some reported issues. All is now clean with no
reported problems in linux-next.
Included in here is:
- interconnect updates
- mei driver updates
- uio updates
- nvmem driver updates
- soundwire updates
- binderfs updates
- coresight updates
- habanalabs updates
- mhi new bus type and core
- extcon driver updates
- some Kconfig cleanups
- other small misc driver cleanups and updates
As mentioned, all have been in linux-next for a while, and with the
last two reverts, all is calm and good"
* tag 'char-misc-5.7-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc: (174 commits)
Revert "driver core: platform: Initialize dma_parms for platform devices"
Revert "amba: Initialize dma_parms for amba devices"
amba: Initialize dma_parms for amba devices
driver core: platform: Initialize dma_parms for platform devices
bus: mhi: core: Drop the references to mhi_dev in mhi_destroy_device()
bus: mhi: core: Initialize bhie field in mhi_cntrl for RDDM capture
bus: mhi: core: Add support for reading MHI info from device
misc: rtsx: set correct pcr_ops for rts522A
speakup: misc: Use dynamic minor numbers for speakup devices
mei: me: add cedar fork device ids
coresight: do not use the BIT() macro in the UAPI header
Documentation: provide IBM contacts for embargoed hardware
nvmem: core: remove nvmem_sysfs_get_groups()
nvmem: core: use is_bin_visible for permissions
nvmem: core: use device_register and device_unregister
nvmem: core: add root_only member to nvmem device struct
extcon: axp288: Add wakeup support
extcon: Mark extcon_get_edev_name() function as exported symbol
extcon: palmas: Hide error messages if gpio returns -EPROBE_DEFER
dt-bindings: extcon: usbc-cros-ec: convert extcon-usbc-cros-ec.txt to yaml format
...
Diffstat (limited to 'Documentation/driver-api')
-rw-r--r-- | Documentation/driver-api/soundwire/stream.rst | 61 |
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 |