kernel/linux.git/Documentation/firmware-guide, branch v6.12.80

Documentation: ACPI: Fix parent device references

2025-08-20T16:30:15+00:00

commit e65cb011349e653ded541dddd6469c2ca813edcf upstream. The _CRS resources in many cases want to have ResourceSource field to be a type of ACPI String. This means that to compile properly we need to enclosure the name path into double quotes. This will in practice defer the interpretation to a run-time stage, However, this may be interpreted differently on different OSes and ACPI interpreter implementations. In particular ACPICA might not correctly recognize the leading '^' (caret) character and will not resolve the relative name path properly. On top of that, this piece may be used in SSDTs which are loaded after the DSDT and on itself may also not resolve relative name paths outside of their own scopes. With this all said, fix documentation to use fully-qualified name paths always to avoid any misinterpretations, which is proven to work. Fixes: 8eb5c87a92c0 ("i2c: add ACPI support for I2C mux ports") Reported-by: Yevhen Kondrashyn Cc: All applicable Signed-off-by: Andy Shevchenko Link: https://patch.msgid.link/20250710170225.961303-1-andriy.shevchenko@linux.intel.com Signed-off-by: Rafael J. Wysocki Signed-off-by: Greg Kroah-Hartman

Documentation: ACPI: Use all-string data node references

2025-06-10T11:12:58+00:00

commit 6db0261f3776bde01ae916ad8e1cb2ded3ba1a2b upstream. Document that references to data nodes shall use string-only references instead of a device reference and a succession of the first package entries of hierarchical data node references. Fixes: 9880702d123f ("ACPI: property: Support using strings in reference properties") Cc: 6.8+ # 6.8+ Signed-off-by: Sakari Ailus Link: https://patch.msgid.link/20250409084738.3657079-1-sakari.ailus@linux.intel.com [ rjw: Clarifying edits ] Signed-off-by: Rafael J. Wysocki Signed-off-by: Greg Kroah-Hartman

Documentation: firmware-guide: ACPI: Fix namespace typo

2024-04-26T16:58:13+00:00

The ACPI namespace has always started with LNXSYSTM, not LNXSYSTEM. Fix the documentation accordingly. Signed-off-by: John Watts Signed-off-by: Rafael J. Wysocki

Merge tag 'acpi-6.9-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm

2024-03-19T18:15:14+00:00

Pull more ACPI updates from Rafael Wysocki: "These update ACPI documentation and kerneldoc comments. Specifics: - Add markup to generate links from footnotes in the ACPI enumeration document (Chris Packham) - Update the handle_eject_request() kerneldoc comment to document the arguments of the function and improve kerneldoc comments for ACPI suspend and hibernation functions (Yang Li)" * tag 'acpi-6.9-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: ACPI: PM: Improve kerneldoc comments for suspend and hibernation functions ACPI: docs: enumeration: Make footnotes links ACPI: Document handle_eject_request() arguments

Merge tag 'cxl-for-6.9' of git://git.kernel.org/pub/scm/linux/kernel/git/cxl/cxl

2024-03-16T17:04:12+00:00

Pull CXL updates from Dan Williams: "CXL has mechanisms to enumerate the performance characteristics of memory devices. Those mechanisms allow Linux to build the equivalent of ACPI SRAT, SLIT, and HMAT tables dynamically at runtime. That capability is necessary because static ACPI can not represent dynamic CXL configurations (and reconfigurations). So, building on the v6.8 work to add "Quality of Service" enumeration, this update plumbs CXL "access coordinates" (read/write access latency and bandwidth) in all the same places that ACPI HMAT feeds similar data. Follow-on patches from the -mm side can then use that data to feed mechanisms like mm/memory-tiers.c. Greg has acked the touch to drivers/base/. The other feature update this cycle is support for CXL error injection via the ACPI EINJ module. That facility enables injection of bus protocol errors provided the user knows the magic address values to insert in the interface. To hide that magic, and make this easier to use, new error injection attributes were added to CXL debugfs. That interface injects the errors relative to a CXL object rather than require user tooling to know how to lookup and inject RCRB (Root Complex Register Block) addresses into the raw EINJ debugfs interface. It received some helpful review comments from Tony, but no explicit acks from the ACPI side. The primary user visible change for existing EINJ users is that they may find that einj.ko was already loaded by cxl_core.ko. Previously, einj.ko was only loaded on demand. The usual collection of miscellaneous cleanups are also present this cycle. Summary: - Supplement ACPI HMAT reported memory performance with native CXL memory performance enumeration - Add support for CXL error injection via the ACPI EINJ mechanism - Cleanup CXL DOE and CDAT integration - Miscellaneous cleanups and fixes" * tag 'cxl-for-6.9' of git://git.kernel.org/pub/scm/linux/kernel/git/cxl/cxl: (21 commits) Documentation/ABI/testing/debugfs-cxl: Fix "Unexpected indentation" lib/firmware_table: Provide buffer length argument to cdat_table_parse() cxl/pci: Get rid of pointer arithmetic reading CDAT table cxl/pci: Rename DOE mailbox handle to doe_mb cxl: Fix the incorrect assignment of SSLBIS entry pointer initial location cxl/core: Add CXL EINJ debugfs files EINJ, Documentation: Update EINJ kernel doc EINJ: Add CXL error type support EINJ: Migrate to a platform driver cxl/region: Deal with numa nodes not enumerated by SRAT cxl/region: Add memory hotplug notifier for cxl region cxl/region: Add sysfs attribute for locality attributes of CXL regions cxl/region: Calculate performance data for a region cxl: Set cxlmd->endpoint before adding port device cxl: Move QoS class to be calculated from the nearest CPU cxl: Split out host bridge access coordinates cxl: Split out combine_coordinates() for common shared usage ACPI: HMAT / cxl: Add retrieval of generic port coordinates for both access classes ACPI: HMAT: Introduce 2 levels of generic port access class base/node / ACPI: Enumerate node access class for 'struct access_coordinate' ...

ACPI: docs: enumeration: Make footnotes links

2024-03-14T15:37:48+00:00

Update the numeric footnotes so that they are rendered as hyperlinks in the html output. Signed-off-by: Chris Packham Signed-off-by: Rafael J. Wysocki

EINJ, Documentation: Update EINJ kernel doc

2024-03-13T06:08:30+00:00

Update EINJ kernel document to include how to inject CXL protocol error types, build the kernel to include CXL error types, and give an example injection. Reviewed-by: Jonathan Cameron Signed-off-by: Ben Cheatham Link: https://lore.kernel.org/r/20240311142508.31717-5-Benjamin.Cheatham@amd.com Signed-off-by: Dan Williams

ACPI: Drop the custom_method debugfs interface

2024-02-22T10:17:48+00:00

The ACPI custom_method debugfs interface is security-sensitive and concurrent access to it is broken [1]. Moreover, the recipe for preparing a customized version of a given control method has changed at one point due to ACPICA changes, which has not been reflected in its documentation, so whoever used it before has had to adapt and it had gone unnoticed for a long time. This interface was a bad idea to start with and its implementation is fragile at the design level. It's been always conceptually questionable, problematic from the security standpoint and implemented poorly. Patches fixing its most apparent functional issues (for example, [2]) don't actually address much of the above. Granted, at the time it was introduced, there was no alternative, but there is the AML debugger in the kernel now and there is the configfs interface allowing custom ACPI tables to be loaded. The former can be used for extensive AML debugging and the latter can be use for testing new AML. [3] Accordingly, drop custom_method along with its (outdated anyway) documentation. Link: https://lore.kernel.org/linux-acpi/20221227063335.61474-1-zh.nvgt@gmail.com/ # [1] Link: https://lore.kernel.org/linux-acpi/20231111132402.4142-1-shiqiang.deng213@gmail.com/ [2] Link: https://stackoverflow.com/questions/62849113/how-to-unload-an-overlay-loaded-using-acpi-config-sysfs # [3] Reported-by: Hang Zhang Signed-off-by: Rafael J. Wysocki Reviewed-by: Zhang Rui Reviewed-by: Kees Cook

ACPI: docs: enumeration: Clarify ACPI bus concepts

2023-10-06T15:29:53+00:00

In some cases, ACPI drivers are implemented as a way to manage devices enumerated with the help of the platform firmware through ACPI. This might be confusing, since the preferred way to implement a driver for a device that cannot be enumerated natively, is a platform driver, as stated in the documentation. Clarify relationships between ACPI device objects, platform devices and ACPI Namespace entries. Suggested-by: Elena Reshetova Co-developed-by: Michal Wilczynski Signed-off-by: Michal Wilczynski Signed-off-by: Rafael J. Wysocki

Merge tag 'docs-6.6' of git://git.lwn.net/linux

2023-08-31T03:05:42+00:00

Pull documentation updates from Jonathan Corbet: "Documentation work keeps chugging along; this includes: - Work from Carlos Bilbao to integrate rustdoc output into the generated HTML documentation. This took some work to figure out how to do it without slowing the docs build and without creating people who don't have Rust installed, but Carlos got there - Move the loongarch and mips architecture documentation under Documentation/arch/ - Some more maintainer documentation from Jakub ... plus the usual assortment of updates, translations, and fixes" * tag 'docs-6.6' of git://git.lwn.net/linux: (56 commits) Docu: genericirq.rst: fix irq-example input: docs: pxrc: remove reference to phoenix-sim Documentation: serial-console: Fix literal block marker docs/mm: remove references to hmm_mirror ops and clean typos docs/zh_CN: correct regi_chg(),regi_add() to region_chg(),region_add() Documentation: Fix typos Documentation/ABI: Fix typos scripts: kernel-doc: fix macro handling in enums scripts: kernel-doc: parse DEFINE_DMA_UNMAP_[ADDR|LEN] Documentation: riscv: Update boot image header since EFI stub is supported Documentation: riscv: Add early boot document Documentation: arm: Add bootargs to the table of added DT parameters docs: kernel-parameters: Refer to the correct bitmap function doc: update params of memhp_default_state= docs: Add book to process/kernel-docs.rst docs: sparse: fix invalid link addresses docs: vfs: clean up after the iterate() removal docs: Add a section on surveys to the researcher guidelines docs: move mips under arch docs: move loongarch under arch ...