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authorLinus Torvalds <torvalds@linux-foundation.org>2026-08-23 13:28:57 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2026-08-23 13:28:57 -0700
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Merge tag 'i3c/for-7.3' of git://git.kernel.org/pub/scm/linux/kernel/git/i3c/linuxgrafted
Pull I3C updates from Alexandre Belloni: "A new driver this cycle, for the AMD AXI I3C controller. There are also new features such as IBI wakeup support, SETAASA device discovery and ACPI support for the the DAA methods, meaning we can now communicate with the SPD devices on DDR5 modules. New driver: - AMD AXI I3C master controller Subsystem: - I3C Common Command Code (CCC) handling improvements, especially around GET CCCs - SETAASA device discovery support - ACPI support for all existing DAA methods like SETDASA, SETNEWDA as well as I2C devices on I3C bus - IBI-based wakeup support Drivers: - dw: SETAASA support - mipi-i3c-hci: advertise IBI wakeup capability, AMD_PT I3C controller support, PIO queue management support for HCI v1.2 - renesas: improve suspend to RAM support, add runtime PM support" * tag 'i3c/for-7.3' of git://git.kernel.org/pub/scm/linux/kernel/git/i3c/linux: (70 commits) i3c: dw: reduce do_daa time if there's no client i3c: mipi-i3c-hci: Add support for AMD_PT I3C controller i3c: mipi-i3c-hci: Add PIO queue management support for HCI v1.2 i3c: mipi-i3c-hci: Fix missing STAT_IBI_STATUS_THLD in PIO mode i3c: dw: rename "pclk" to "apb" to match dt-binding i3c: dw: make struct dw_i3c_cmd smaller i3c: dw: use COMMAND_PORT_TRANSFER_ARG instead of hardcoding i3c: renesas: Don't register devices when ENTDAA times out i3c: master: dw-i3c-master: fix OD timing for first broadcast i3c: mipi-i3c-hci: Advertise IBI wakeup capability i3c: mipi-i3c-hci: Factor out i3c_hci_sysdev() i3c: mipi-i3c-hci-pci: Propagate I3C wakeup requirements to PCI i3c: master: Reject IBI requests from non-IBI-capable devices i3c: master: Add helper to query bus wakeup requirements i3c: master: Report wakeup events for IBIs i3c: master: Support IBI-based wakeup capability i3c: master: Fix potential UAF in i3c_device_match() i3c: master: Fix potential UAF in i3c_device_uevent() i3c: Make dev->desc locking assumptions explicit i3c: master: Fix use-after-free of master->this ...
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+=================
+SoundWire Locking
+=================
+
+This document explains locking mechanism of the SoundWire Bus. Bus uses
+following locks in order to avoid race conditions in Bus operations on
+shared resources.
+
+ - Bus lock
+
+ - Message lock
+
+Bus lock
+========
+
+SoundWire Bus lock is a mutex and is part of Bus data structure
+(sdw_bus) which is used for every Bus instance. This lock is used to
+serialize each of the following operations(s) within SoundWire Bus instance.
+
+ - Addition and removal of Slave(s), changing Slave status.
+
+ - Prepare, Enable, Disable and De-prepare stream operations.
+
+ - Access of Stream data structure.
+
+Message lock
+============
+
+SoundWire message transfer lock. This mutex is part of
+Bus data structure (sdw_bus). This lock is used to serialize the message
+transfers (read/write) within a SoundWire Bus instance.
+
+Below examples show how locks are acquired.
+
+Example 1
+---------
+
+Message transfer.
+
+ 1. For every message transfer
+
+ a. Acquire Message lock.
+
+ b. Transfer message (Read/Write) to Slave1 or broadcast message on
+ Bus in case of bank switch.
+
+ c. Release Message lock
+
+ ::
+
+ +----------+ +---------+
+ | | | |
+ | Bus | | Master |
+ | | | Driver |
+ | | | |
+ +----+-----+ +----+----+
+ | |
+ | bus->ops->xfer_msg() |
+ <-------------------------------+ a. Acquire Message lock
+ | | b. Transfer message
+ | |
+ +-------------------------------> c. Release Message lock
+ | return success/error | d. Return success/error
+ | |
+ + +
+
+Example 2
+---------
+
+Prepare operation.
+
+ 1. Acquire lock for Bus instance associated with Master 1.
+
+ 2. For every message transfer in Prepare operation
+
+ a. Acquire Message lock.
+
+ b. Transfer message (Read/Write) to Slave1 or broadcast message on
+ Bus in case of bank switch.
+
+ c. Release Message lock.
+
+ 3. Release lock for Bus instance associated with Master 1 ::
+
+ +----------+ +---------+
+ | | | |
+ | Bus | | Master |
+ | | | Driver |
+ | | | |
+ +----+-----+ +----+----+
+ | |
+ | sdw_prepare_stream() |
+ <-------------------------------+ 1. Acquire bus lock
+ | | 2. Perform stream prepare
+ | |
+ | |
+ | bus->ops->xfer_msg() |
+ <-------------------------------+ a. Acquire Message lock
+ | | b. Transfer message
+ | |
+ +-------------------------------> c. Release Message lock
+ | return success/error | d. Return success/error
+ | |
+ | |
+ | return success/error | 3. Release bus lock
+ +-------------------------------> 4. Return success/error
+ | |
+ + +