Go to file
André Draszik 304f5784e9
regulator: core: reresolve unresolved supplies when available
When a regulator A and its supply B are provided by different devices,
the driver implementing B might be last to probe (with A still
pending resolution of its supply B). While we try to resolve all
pending supplies for all regulators (including A) during
regulator_register() of B via regulator_register_resolve_supply(),
supply resolution will still not work for A as the driver for B hasn't
finished binding to the PMIC device corresponding to B at that stage
yet. The regulator core explicitly only allows supplies from other
devices to be used once the relevant driver has fully bound, mainly to
avoid having to deal with cases where B itself might -EPROBE_DEFER.

In this case, A's supply will only be resolved as part of the core's
regulator_init_complete_work_function(), which currently is scheduled
to run after 30s. This was added as a work-around in
commit 3827b64dba ("regulator: core: Resolve supplies before
disabling unused regulators") to cover this situation.

There are two problems with that approach:
* it potentially runs long after all our consumers have probed
* an upcoming change will allow regulator_register() to complete
  successfully even when required supplies (e.g. due to always-on or
  boot-on) are missing at register time, deferring full configuration
  of the regulator (and usability by consumers, i.e. usually consumer
  probe) until the supply becomes available.
  Resolving supplies in the late work func can therefore make it
  impossible for consumers to probe at all, as the driver core will not
  know to reprobe consumers when supplies have resolved.

We could schedule an earlier work to try to resolve supplies sooner,
but that'd be racy as consumers of A might try to probe before A's
supply gets fully resolved via this extra work.

Instead, add a very simple regulator bus and add a dummy device with a
corresponding driver to it for each regulator that is missing its
supply during regulator_register(). This way, the driver core will call
our bus' probe whenever a new (regulator) device was successfully
bound, allowing us to retry resolving the supply during (our bus) probe
and to bind this dummy device if successful. In turn this means the
driver core will see a newly bound device and retry probing of all
pending consumers, if any.

With that in place, we can avoid walking the full list of all known
regulators to try resolve missing supplies during regulator_register(),
as the driver core will invoke the bus probe for regulators that are
still pending their supplies. We can also drop the code trying to
resolve supplies one last time before unused regulators get disabled,
as all supplies should have resolved at that point in time, and if they
haven't then there's no point in trying again, as the outcome won't
change.

Note: We can not reuse the existing struct device created for each
rail, as a device can not be part of a class and a bus simultaneously.

Signed-off-by: André Draszik <andre.draszik@linaro.org>
Link: https://patch.msgid.link/20260109-regulators-defer-v2-7-1a25dc968e60@linaro.org
Signed-off-by: Mark Brown <broonie@kernel.org>
2026-01-09 13:38:00 +00:00
Documentation RISC-V updates for v6.19-rc3 2025-12-28 09:44:26 -08:00
LICENSES LICENSES: Add modern form of the LGPL-2.1 tags to the usage guide section 2025-10-22 07:58:19 +02:00
arch Fix the AMD microcode Entrysign signature checking code to include more 2026-01-02 12:04:51 -08:00
block block-6.19-20260102 2026-01-02 12:15:59 -08:00
certs sign-file,extract-cert: use pkcs11 provider for OPENSSL MAJOR >= 3 2024-09-20 19:52:48 +03:00
crypto crypto: seqiv - Do not use req->iv after crypto_aead_encrypt 2025-12-19 14:47:06 +08:00
drivers regulator: core: reresolve unresolved supplies when available 2026-01-09 13:38:00 +00:00
fs four smb3 server fixes 2026-01-02 09:24:43 -08:00
include regulator: core: reresolve unresolved supplies when available 2026-01-09 13:38:00 +00:00
init Significant patch series in this pull request: 2025-12-06 14:01:20 -08:00
io_uring io_uring-6.19-20260102 2026-01-02 12:07:55 -08:00
ipc Significant patch series in this pull request: 2025-12-06 14:01:20 -08:00
kernel Power management fix for 6.19-rc4 2026-01-02 12:35:29 -08:00
lib idr: fix idr_alloc() returning an ID out of range 2025-12-23 11:23:11 -08:00
mm mm/ksm: fix pte_unmap_unlock of wrong address in break_ksm_pmd_entry 2025-12-23 11:23:17 -08:00
net Including fixes from Bluetooth and WiFi. Notably this includes the fix 2025-12-30 08:45:58 -08:00
rust 27 hotfixes. 12 are cc:stable, 18 are MM. 2025-12-29 11:40:38 -08:00
samples samples/ftrace: Adjust LoongArch register restore order in direct calls 2025-12-31 15:19:25 +08:00
scripts mcb: Add missing modpost build support 2025-12-27 20:48:01 +01:00
security kernel/kexec: change the prototype of kimage_map_segment() 2025-12-23 11:23:13 -08:00
sound ALSA: hda/realtek: fix PCI SSID for one of the HP 200 G2i laptop 2025-12-21 11:19:31 +01:00
tools perf-tools fixes and updates for v6.19 2026-01-02 14:24:09 -08:00
usr initramfs: add gen_init_cpio to hostprogs unconditionally 2025-11-26 21:55:40 +01:00
virt KVM fixes for 6.19-rc1 2025-12-18 18:38:45 +01:00
.clang-format s390/pci: Fix cyclic dead-lock in zpci_zdev_put() and zpci_scan_devices() 2025-12-14 11:03:58 +01:00
.clippy.toml rust: clean Rust 1.88.0's warning about `clippy::disallowed_macros` configuration 2025-05-07 00:11:47 +02:00
.cocciconfig
.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 rust: kbuild: add proc macro library support 2025-11-24 17:15:36 +01:00
.mailmap .mailmap: remove one of the entries for WangYuli 2025-12-23 11:23:13 -08:00
.pylintrc docs: Move the python libraries to tools/lib/python 2025-11-18 09:22:40 -07:00
.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 Including fixes from netfilter and CAN. 2025-12-19 07:55:35 +12:00
Kbuild sched: Make migrate_{en,dis}able() inline 2025-09-25 09:57:16 +02:00
Kconfig io_uring: Rename KConfig to Kconfig 2025-02-19 14:53:27 -07:00
MAINTAINERS 27 hotfixes. 12 are cc:stable, 18 are MM. 2025-12-29 11:40:38 -08:00
Makefile Linux 6.19-rc4 2026-01-04 14:41:55 -08:00
README README: restructure with role-based documentation and guidelines 2025-11-29 08:40:33 -07:00

README

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

The Linux kernel is the core of any Linux operating system. It manages hardware,
system resources, and provides the fundamental services for all other software.

Quick Start
-----------

* Report a bug: See Documentation/admin-guide/reporting-issues.rst
* Get the latest kernel: https://kernel.org
* Build the kernel: See Documentation/admin-guide/quickly-build-trimmed-linux.rst
* Join the community: https://lore.kernel.org/

Essential Documentation
-----------------------

All users should be familiar with:

* Building requirements: Documentation/process/changes.rst
* Code of Conduct: Documentation/process/code-of-conduct.rst
* License: See COPYING

Documentation can be built with make htmldocs or viewed online at:
https://www.kernel.org/doc/html/latest/


Who Are You?
============

Find your role below:

* New Kernel Developer - Getting started with kernel development
* Academic Researcher - Studying kernel internals and architecture
* Security Expert - Hardening and vulnerability analysis
* Backport/Maintenance Engineer - Maintaining stable kernels
* System Administrator - Configuring and troubleshooting
* Maintainer - Leading subsystems and reviewing patches
* Hardware Vendor - Writing drivers for new hardware
* Distribution Maintainer - Packaging kernels for distros


For Specific Users
==================

New Kernel Developer
--------------------

Welcome! Start your kernel development journey here:

* Getting Started: Documentation/process/development-process.rst
* Your First Patch: Documentation/process/submitting-patches.rst
* Coding Style: Documentation/process/coding-style.rst
* Build System: Documentation/kbuild/index.rst
* Development Tools: Documentation/dev-tools/index.rst
* Kernel Hacking Guide: Documentation/kernel-hacking/hacking.rst
* Core APIs: Documentation/core-api/index.rst

Academic Researcher
-------------------

Explore the kernel's architecture and internals:

* Researcher Guidelines: Documentation/process/researcher-guidelines.rst
* Memory Management: Documentation/mm/index.rst
* Scheduler: Documentation/scheduler/index.rst
* Networking Stack: Documentation/networking/index.rst
* Filesystems: Documentation/filesystems/index.rst
* RCU (Read-Copy Update): Documentation/RCU/index.rst
* Locking Primitives: Documentation/locking/index.rst
* Power Management: Documentation/power/index.rst

Security Expert
---------------

Security documentation and hardening guides:

* Security Documentation: Documentation/security/index.rst
* LSM Development: Documentation/security/lsm-development.rst
* Self Protection: Documentation/security/self-protection.rst
* Reporting Vulnerabilities: Documentation/process/security-bugs.rst
* CVE Procedures: Documentation/process/cve.rst
* Embargoed Hardware Issues: Documentation/process/embargoed-hardware-issues.rst
* Security Features: Documentation/userspace-api/seccomp_filter.rst

Backport/Maintenance Engineer
-----------------------------

Maintain and stabilize kernel versions:

* Stable Kernel Rules: Documentation/process/stable-kernel-rules.rst
* Backporting Guide: Documentation/process/backporting.rst
* Applying Patches: Documentation/process/applying-patches.rst
* Subsystem Profile: Documentation/maintainer/maintainer-entry-profile.rst
* Git for Maintainers: Documentation/maintainer/configure-git.rst

System Administrator
--------------------

Configure, tune, and troubleshoot Linux systems:

* Admin Guide: Documentation/admin-guide/index.rst
* Kernel Parameters: Documentation/admin-guide/kernel-parameters.rst
* Sysctl Tuning: Documentation/admin-guide/sysctl/index.rst
* Tracing/Debugging: Documentation/trace/index.rst
* Performance Security: Documentation/admin-guide/perf-security.rst
* Hardware Monitoring: Documentation/hwmon/index.rst

Maintainer
----------

Lead kernel subsystems and manage contributions:

* Maintainer Handbook: Documentation/maintainer/index.rst
* Pull Requests: Documentation/maintainer/pull-requests.rst
* Managing Patches: Documentation/maintainer/modifying-patches.rst
* Rebasing and Merging: Documentation/maintainer/rebasing-and-merging.rst
* Development Process: Documentation/process/maintainer-handbooks.rst
* Maintainer Entry Profile: Documentation/maintainer/maintainer-entry-profile.rst
* Git Configuration: Documentation/maintainer/configure-git.rst

Hardware Vendor
---------------

Write drivers and support new hardware:

* Driver API Guide: Documentation/driver-api/index.rst
* Driver Model: Documentation/driver-api/driver-model/driver.rst
* Device Drivers: Documentation/driver-api/infrastructure.rst
* Bus Types: Documentation/driver-api/driver-model/bus.rst
* Device Tree Bindings: Documentation/devicetree/bindings/
* Power Management: Documentation/driver-api/pm/index.rst
* DMA API: Documentation/core-api/dma-api.rst

Distribution Maintainer
-----------------------

Package and distribute the kernel:

* Stable Kernel Rules: Documentation/process/stable-kernel-rules.rst
* ABI Documentation: Documentation/ABI/README
* Kernel Configuration: Documentation/kbuild/kconfig.rst
* Module Signing: Documentation/admin-guide/module-signing.rst
* Kernel Parameters: Documentation/admin-guide/kernel-parameters.rst
* Tainted Kernels: Documentation/admin-guide/tainted-kernels.rst



Communication and Support
=========================

* Mailing Lists: https://lore.kernel.org/
* IRC: #kernelnewbies on irc.oftc.net
* Bugzilla: https://bugzilla.kernel.org/
* MAINTAINERS file: Lists subsystem maintainers and mailing lists
* Email Clients: Documentation/process/email-clients.rst