kernel/linux.git/include/linux/soundwire/sdw.h, branch v5.6.15

soundwire: bus: fix device number leak on errors

2020-01-14T06:35:52+00:00

If the programming of the dev_number fails due to an IO error, a new device_number will be assigned, resulting in a leak. Make sure we only assign a device_number once per Slave device. Signed-off-by: Pierre-Louis Bossart Link: https://lore.kernel.org/r/20200113225637.17313-1-pierre-louis.bossart@linux.intel.com Signed-off-by: Vinod Koul

soundwire: sdw_slave: track unattach_request to handle all init sequences

2019-12-12T03:47:06+00:00

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 Link: https://lore.kernel.org/r/20191212014507.28050-5-pierre-louis.bossart@linux.intel.com Signed-off-by: Vinod Koul

soundwire: sdw_slave: add initialization_complete definition

2019-12-12T03:47:06+00:00

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 Link: https://lore.kernel.org/r/20191212014507.28050-4-pierre-louis.bossart@linux.intel.com Signed-off-by: Vinod Koul

soundwire: sdw_slave: add enumeration_complete structure

2019-12-12T03:47:06+00:00

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 Link: https://lore.kernel.org/r/20191212014507.28050-3-pierre-louis.bossart@linux.intel.com Signed-off-by: Vinod Koul

soundwire: sdw_slave: add probe_complete structure and new fields

2019-12-12T03:47:06+00:00

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 Link: https://lore.kernel.org/r/20191212014507.28050-2-pierre-louis.bossart@linux.intel.com Signed-off-by: Vinod Koul

soundwire: remove bitfield for unique_id, use u8

2019-11-09T11:16:56+00:00

There is no good reason why the unique_id needs to be stored as 4 bits. The code will work without changes with a u8 since all values are already filtered while parsing the ACPI tables and Slave devID registers. Use u8 representation. This will allow us to encode a "IGNORE_UNIQUE_ID" value to account for firmware/BIOS creativity. Signed-off-by: Pierre-Louis Bossart Link: https://lore.kernel.org/r/20191022234808.17432-2-pierre-louis.bossart@linux.intel.com Signed-off-by: Vinod Koul

soundwire: remove DAI_ID_RANGE definitions

2019-10-21T04:20:53+00:00

There is no reason to reserve a range of DAI IDs for SoundWire. This is not scalable and it's better to let the ASoC core allocate the dai->id when registering a component. Signed-off-by: Pierre-Louis Bossart Link: https://lore.kernel.org/r/20190916192348.467-3-pierre-louis.bossart@linux.intel.com Signed-off-by: Vinod Koul

soundwire: stream: make stream name a const pointer

2019-09-04T09:27:28+00:00

Make stream name const pointer Signed-off-by: Srinivas Kandagatla Link: https://lore.kernel.org/r/20190813083550.5877-3-srinivas.kandagatla@linaro.org Signed-off-by: Vinod Koul

soundwire: Add compute_params callback

2019-09-04T09:27:19+00:00

This callback allows masters to compute the bus parameters required. Signed-off-by: Srinivas Kandagatla Link: https://lore.kernel.org/r/20190813083550.5877-2-srinivas.kandagatla@linaro.org Signed-off-by: Vinod Koul

soundwire: intel: handle disabled links

2019-08-23T06:32:56+00:00

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 Link: https://lore.kernel.org/r/20190821185821.12690-5-pierre-louis.bossart@linux.intel.com Signed-off-by: Vinod Koul