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| author | Linus Torvalds <torvalds@linux-foundation.org> | 2026-08-19 10:09:22 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2026-08-19 10:09:22 -0700 |
| commit | f4cdf7ca9a1fdcca413157df19753f388a5a224e (patch) | |
| tree | 60a31895b2446cd7fa27514e8c2843534a0de0da /Documentation/driver-api/soundwire/locking.rst | |
| download | linux-stable-f4cdf7ca9a1fdcca413157df19753f388a5a224e.tar.gz linux-stable-f4cdf7ca9a1fdcca413157df19753f388a5a224e.zip | |
Merge tag 'media/v7.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-mediagrafted
Pull media updates from Mauro Carvalho Chehab:
- v4l2-core: added ISP statistics support and per-block validation
- v4l2-core: Allow unknown HDR10 white point and luminance
- New camera sensors: Sony IMX678 and IMX471m, Himax HM1092 IR sensor
- New codec: Milos: VPU v2.0 codec support
- isp driver: gained support for Dreamchip RPPX1 ISP framework
- vsp1 driver: gained support for RZ/T2H and RZ/N2H
- Novalake driver: gained CVS support for new NVL hardware
- dvb-core: fix feed leak on failed DMX_ADD_PID
- several driver fixes, cleanups and minor improvements
* tag 'media/v7.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media: (308 commits)
media: ipu-bridge: check all DMI entries when overriding sensor rotation
media: v4l2-async: avoid deleting unlinked ASC entry on link error
media: rzg2l-cru: Align bytesperline to hardware DMA stride requirement
media: intel/ipu6: fix async notifier cleanup leak on parse error
media: staging/ipu7: fix async notifier UAF on probe error path
media: amd: isp4: fix self-deadlock in isp4sd_pwron_and_init() error path
media: amd: isp4: release partial allocations in isp4if_alloc_fw_gpumem()
media: rcar-isp: Fix VSPX reference leaks
media: rcar-isp: Release ISPCORE resources
media: i2c: imx415: Release runtime PM reference on VBLANK error
media: i2c: imx415: Return test pattern write errors
media: renesas: vsp1: Declare index variables in for loop statement
media: renesas: vsp1: Make reset control optional to support platforms without a reset line
media: dt-bindings: media: renesas,vsp1: Document RZ/T2H and RZ/N2H SoCs
media: dt-bindings: media: renesas,fcp: Document RZ/T2H and RZ/N2H SoCs
media: nxp: imx8-isi: Add additional 32-bit RGB format support
media: nxp: imx8-isi: Add 16-bit raw Bayer format support
media: nxp: imx8-isi: Implement per-stream reference counting for multiplexed streams
media: nxp: imx8-isi: Use BIT_ULL() for 64-bit stream masks
media: nxp: imx8-isi: Correct color map between V4L2 and ISI
...
Diffstat (limited to 'Documentation/driver-api/soundwire/locking.rst')
| -rw-r--r-- | Documentation/driver-api/soundwire/locking.rst | 108 |
1 files changed, 108 insertions, 0 deletions
diff --git a/Documentation/driver-api/soundwire/locking.rst b/Documentation/driver-api/soundwire/locking.rst new file mode 100644 index 000000000..3a7ffb3d8 --- /dev/null +++ b/Documentation/driver-api/soundwire/locking.rst @@ -0,0 +1,108 @@ +================= +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 + | | + + + |
