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Ming Wang a4da5317cf irqchip/loongson-pch-lpc: Use legacy domain for PCH-LPC IRQ controller 
[ Upstream commit c33c43f71b ]

On certain Loongson platforms, drivers attempting to request a legacy
ISA IRQ directly via request_irq() (e.g., IRQ 4) may fail. The
virtual IRQ descriptor is not fully initialized and lacks a valid irqchip.

This issue does not affect ACPI-enumerated devices described in DSDT,
as their interrupts are properly mapped via the GSI translation path.
This indicates the LPC irqdomain itself is functional but is not correctly
handling direct VIRQ-to-HWIRQ mappings.

The root cause is the use of irq_domain_create_linear(). This API sets
up a domain for dynamic, on-demand mapping, typically triggered by a GSI
request. It does not pre-populate the mappings for the legacy VIRQ range
(0-15). Consequently, if no ACPI device claims a specific GSI
(e.g., GSI 4), the corresponding VIRQ (e.g., VIRQ 4) is never mapped to
the LPC domain. A direct call to request_irq(4, ...) then fails because
the kernel cannot resolve this VIRQ to a hardware interrupt managed by
the LPC controller.

The PCH-LPC interrupt controller is an i8259-compatible legacy device
that requires a deterministic, static 1-to-1 mapping for IRQs 0-15 to
support legacy drivers.

Fix this by replacing irq_domain_create_linear() with
irq_domain_create_legacy(). This API is specifically designed for such
controllers. It establishes the required static 1-to-1 VIRQ-to-HWIRQ
mapping for the entire legacy range (0-15) immediately upon domain
creation. This ensures that any VIRQ in this range is always resolvable,
making direct calls to request_irq() for legacy IRQs function correctly.

Signed-off-by: Ming Wang <wangming01@loongson.cn>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
History 2025-11-13 15:36:49 -05:00
arch arc: Fix __fls() const-foldability via __builtin_clzl() 2025-11-13 15:36:48 -05:00
block block: check for valid bio while splitting 2025-11-13 15:36:49 -05:00
certs sign-file,extract-cert: use pkcs11 provider for OPENSSL MAJOR >= 3 2024-09-20 19:52:48 +03:00
crypto crypto: essiv - Check ssize for decryption and in-place encryption 2025-10-19 16:37:14 +02:00
Documentation dpll: spec: add missing module-name and clock-id to pin-get reply 2025-11-13 15:36:42 -05:00
drivers irqchip/loongson-pch-lpc: Use legacy domain for PCH-LPC IRQ controller 2025-11-13 15:36:49 -05:00
fs smb: client: fix potential cfid UAF in smb2_query_info_compound 2025-11-13 15:36:38 -05:00
include block: check for valid bio while splitting 2025-11-13 15:36:49 -05:00
init init: handle bootloader identifier in kernel parameters 2025-10-19 16:37:27 +02:00
io_uring io_uring/rsrc: respect submitter_task in io_register_clone_buffers() 2025-11-13 15:36:49 -05:00
ipc vfs-6.17-rc1.mmap_prepare 2025-07-28 13:43:25 -07:00
kernel bpf: Use tnums for JEQ/JNE is_branch_taken logic 2025-11-13 15:36:46 -05:00
lib kunit: test_dev_action: Correctly cast 'priv' pointer to long* 2025-11-13 15:36:39 -05:00
LICENSES LICENSES: Replace the obsolete address of the FSF in the GFDL-1.2 2025-07-24 11:15:39 +02:00
mm treewide: remove MIGRATEPAGE_SUCCESS 2025-10-29 14:10:32 +01:00
net mptcp: fix MSG_PEEK stream corruption 2025-11-13 15:36:45 -05:00
rust rust: device: fix device context of Device::parent() 2025-10-29 14:10:22 +01:00
samples 15 hotfixes. 11 are cc:stable and the remainder address post-6.16 issues 2025-09-17 21:34:26 -07:00
scripts kbuild: Add '.rel.*' strip pattern for vmlinux 2025-10-19 16:37:15 +02:00
security KEYS: trusted_tpm1: Compare HMAC values in constant time 2025-10-19 16:37:28 +02:00
sound ASoC: soc_sdw_utils: remove cs42l43 component_name 2025-11-13 15:36:42 -05:00
tools selftests/bpf: Fix incorrect array size calculation 2025-11-13 15:36:49 -05:00
usr usr/include: openrisc: don't HDRTEST bpf_perf_event.h 2025-05-12 15:03:17 +09:00
virt Merge tag 'kvm-x86-no_assignment-6.17' of https://github.com/kvm-x86/linux into HEAD 2025-07-29 08:36:42 -04:00
.clang-format Linux 6.15-rc5 2025-05-06 16:39:25 +10:00
.clippy.toml rust: clean Rust 1.88.0's warning about clippy::disallowed_macros configuration 2025-05-07 00:11:47 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.editorconfig .editorconfig: remove trim_trailing_whitespace option 2024-06-13 16:47:52 +02:00
.get_maintainer.ignore MAINTAINERS: remove Alyssa Rosenzweig 2025-09-18 21:17:31 +02:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore gitignore: allow .pylintrc to be tracked 2025-07-02 17:10:04 -06:00
.mailmap 7 hotfixes. 4 are cc:stable and the remainder address post-6.16 issues or 2025-09-28 09:32:00 -07:00
.pylintrc docs: add a .pylintrc file with sys path for docs scripts 2025-04-09 12:10:33 -06:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: retire Boris from TLS maintainers 2025-08-26 17:36:01 -07:00
Kbuild drm: ensure drm headers are self-contained and pass kernel-doc 2025-02-12 10:44:43 +02:00
Kconfig io_uring: Rename KConfig to Kconfig 2025-02-19 14:53:27 -07:00
MAINTAINERS i2c-for-6.17-rc8 2025-09-28 13:19:23 -07:00
Makefile Linux 6.17.7 2025-11-02 22:18:05 +09:00
README README: Fix spelling 2024-03-18 03:36:32 -06:00

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.