Due to power rail dependencies, the SoundWire Master driver cannot
make decisions on its own when entering pm runtime suspend.
Add quirk mask for each link, so that the SOF parent driver can inform
the SoundWire master driver of the desired behavior:
a) leave clock on
b) power-off instead of clock stop
c) power-off if all devices cannot generate wakes
d) force bus reset on clock restart
Note that for now the interface with the SOF driver relies on a single
mask for all links. If needed, the interface might be modified at a
later point to provide more freedom. The code at the lower level does
not assume any commonality between links.
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20191212014507.28050-12-pierre-louis.bossart@linux.intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Some of the Intel SoundWire SHIM registers contain fields for
different links. Without protection, the master drivers for the
different links will access these shared registers, leading to invalid
configurations and timeouts (specifically when changing CPA/SPA
power-related registers and polling for the changes to be applied).
A mutex is added to make sure all rmw access to those registers are
serialized.
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20191212014507.28050-11-pierre-louis.bossart@linux.intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
The SoundWire DAIs for Intel platform are created in
drivers/soundwire/intel.c, while the communication with the Intel DSP
is all controlled in soc/sof/intel
When the DAI status changes, a callback is used to bridge the gap
between the two subsystems.
The naming of the existing 'config_stream' callback does not map well
with any of ALSA/ASoC concepts. This patch renames it as
'params_stream' to be more self-explanatory.
A new 'free_stream' callback is added in case any resources allocated
in the 'params_stream' stage need to be released. In the SOF
implementation, this is used in the hw_free case to release the DMA
channels over IPC.
These two callbacks now rely on structures which expose the link_id
and alh_stream_id (required by the firmware IPC), instead of a list of
parameters. The 'void *' definitions are changed to use explicit
types, as suggested on alsa-devel during earlier reviews.
Signed-off-by: Rander Wang <rander.wang@linux.intel.com>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20191212014507.28050-7-pierre-louis.bossart@linux.intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
The current interfaces between ASoC and SoundWire are limited by the
platform_device infrastructure to an init() and exit() (mapped to the
platform driver.probe and .remove)
To help with the platform detection, machine driver selection and
management of power dependencies between DSP and SoundWire IP, the
ASoC side requires:
a) an ACPI scan helper, to report if any devices are exposed in the
DSDT tables, and if any links are disabled by the BIOS.
b) a probe helper that allocates the resources without actually
starting the bus.
c) a startup helper which does start the bus when all power
dependencies are settled.
d) an exit helper to free all resources
e) an interrupt_enable/disable helper, typically invoked after the
startup helper but also used in suspend routines.
This patch moves all required interfaces to sdw_intel.h, mainly to
allow SoundWire and ASoC parts to be merged separately once the header
files are shared between trees.
To avoid compilation issues, the conflicts in intel_init.c are blindly
removed. This would in theory prevent the code from working, but since
there are no users of the Intel Soundwire driver this has no
impact. Functionality will be restored when the removal of platform
devices is complete.
Support for SoundWire + SOF builds will only be provided once all the
required pieces are upstream.
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20191212014507.28050-6-pierre-louis.bossart@linux.intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
The Slave device initialization can be split in 4 different cases:
1. Master-initiated hardware reset, system suspend-resume and
pm_runtime based on clock-stop mode1. To avoid timeouts and a bad
audio experience, the Slave device resume operations need to wait for
the Slave device to be re-enumerated and its settings restored.
2. Exit from clock-stop mode0. In this case, the Slave device is
required to remain enumerated and its context preserved while the
clock is stopped, so no re-initialization or wait_for_completion() is
necessary.
3. Slave-initiated pm_runtime D3 transition. With the parent child
relationship, it is possible that a Slave device becomes 'suspended'
while its parent is still 'active' with the bus clock still
toggling. In this case, during the pm_runtime resume operation, there
is no need to wait for any settings to be restored.
4. Slave reset (sync loss or implementation-defined). In that case the
bus remains operational and the Slave device will be re-initialized
when it becomes ATTACHED again.
In previous patches, we suggested the use of wait_for_completion() to
deal with the case #1, but case #2 and #3 do not need any wait.
To account for those differences, this patch adds an unattach_request
field. The field is explicitly set by the Master for the case #1, and
if non-zero the Slave device shall wait on resume. In all other cases,
the Slave resume operations can proceed without wait.
The only request tracked so far is Master HardReset, but the request
is declared as a bit mask for future extensions (if needed). The
definition for this value is added in bus.h and does not need to be
exposed in sdw.h
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20191212014507.28050-5-pierre-louis.bossart@linux.intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Slave drivers may have different ways of handling their settings, with
or without regmap.
During the integration of codec drivers, done in partnership between
Intel and Realtek, it became desirable to implement a predictable
order between low-level initializations performed in .update_status()
(invoked by an interrupt thread) and the settings restored in the
resume steps (invoked by the PM core).
This patch builds on the previous solution to wait for the Slave
device to be fully enumerated. The complete() in this case is signaled
not before the .update_status() is called, but after .update_status()
returns. Without this patch, the settings were not properly restored,
leading to timing-dependent 'no sound after resume' or 'no headset
detected after resume' bug reports.
Depending on how initialization is handled, a Slave device driver may
wait for enumeration_complete, or for initialization_complete, both
are valid synchronization points. They are initialized at the same
time, they only differ on when complete() is invoked.
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20191212014507.28050-4-pierre-louis.bossart@linux.intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
When the Master starts the bus (be it during the initial boot or
system resume), it usually performs a HardReset to make sure
electrical levels are correct, then enables the control channel.
While the PM framework guarantees that the Slave devices will only
become 'active' once the Master completes the bus initialization,
there is still a risk of a race condition: the Slave enumeration is
handled in a separate interrupt thread triggered by hardware status
changes, so the Slave device may not be ready to accept commands when
the Slave driver tries to access the registers and restore settings in
its resume or pm_runtime_resume callbacks. In those cases, any
read/write commands from/to the Slave device will result in a timeout.
This patch adds an enumeration_complete structure. When the bus is
goes through a HardReset sequence and restarted, the Slave will be
marked as UNATTACHED, which will result in a call to
init_completion().
When the Slave reports its presence during PING frames as a non-zero
Device, the Master hardware will issue an interrupt and the bus driver
will invoke complete(). The order between init_completion()/complete()
is predictable since this is a Master-initiated transition.
The Slave driver may use wait_for_completion() in its resume callback.
When regmap is used, the Slave driver will typically set its regmap in
cache-only mode on suspend, then on resume block on
wait_for_completion(&enumeration_complete) to guarantee it is safe to
start read/write transactions. It may then exit the cache-only mode
and use a regmap_sync to restore settings. All these steps are
optional, their use completely depends on the Slave device
capabilities and how the Slave driver is implemented.
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20191212014507.28050-3-pierre-louis.bossart@linux.intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
When a Slave device becomes synchronized with the bus, it may report
its presence in PING frames, as well as optionally asserting an
in-band PREQ signal.
The bus driver will detect a new Device0, start the enumeration
process and assign it a non-zero device number. The SoundWire
enumeration provides an arbitration to deal with multiple Slaves
reporting ATTACHED at the same time. The bus driver will also invoke
the driver .probe() callback associated with this device. The probe()
depends on the Linux device core, which handles the match operations
and may result in modules being loaded.
Once the non-zero device number is programmed, the Slave will report
its new status in PING frames and the Master hardware will typically
report this status change with an interrupt. At this point, the
.update_status() callback of the codec driver will be invoked (usually
from an interrupt thread or workqueue scheduled from the interrupt
thread).
The first race condition which can happen is between the .probe(),
which allocates the resources, and .update_status() where
initializations are typically handled. The .probe() is only called
once during the initial boot, while .update_status() will be called
for every bus hardware reset and if the Slave device loses
synchronization (an unlikely event but with non-zero probability).
The time difference between the end of the enumeration process and a
change of status reported by the hardware may be as small as one
SoundWire PING frame. The scheduling of the interrupt thread, which
invokes .update_status() is not deterministic, but can be small enough
to create a race condition. With a 48 kHz frame rate and ideal
scheduling cases, the .probe() may be pre-empted within double-digit
microseconds.
Since there is no guarantee that the .probe() completes by the time
.update_status() is invoked as a result of an interrupt, it's not
unusual for the .update_status() to rely on data structures that have
not been allocated yet, leading to kernel oopses.
This patch adds a probe_complete utility, which is used in the
sdw_update_slave_status() routine. The codec driver does not need to
do anything and can safely assume all resources are allocated in its
update_status() callback.
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20191212014507.28050-2-pierre-louis.bossart@linux.intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
On most hardware platforms, SoundWire interfaces are pin-muxed with
other interfaces (typically DMIC or I2S) and the status of each link
needs to be checked at boot time.
For Intel platforms, the BIOS provides a menu to enable/disable the
links separately, and the information is provided to the OS with an
Intel-specific _DSD property. The same capability will be added to
revisions of the MIPI DisCo specification.
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20190821185821.12690-5-pierre-louis.bossart@linux.intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
This Helper macro is for SoundWire drivers which do not do anything special in
module init/exit. This eliminates a lot of boilerplate. Each module may only
use this macro once, and calling it replaces module_init() and module_exit()
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Vinod Koul <vkoul@kernel.org>
The existing definitions are ambiguous and possibly misleading.
For DP0, 'flow-control' is only relevant for the BRA protocol and
should not be confused with async modes explicitly not supported for
DP0, add prefix to follow MIPI DisCo definition
The use of 'device_interrupts' is also questionable. The MIPI
SoundWire spec defines Slave-, DP0- and DPN-level
implementation-defined interrupts. Using the 'device' prefix in the
last two cases is misleading, not only is the term 'device' overloaded
but these properties are only valid at the DP0 and DPn levels. Rename
to follow the MIPI definitions, no need to be creative here.
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Vinod Koul <vkoul@kernel.org>
