kernel/linux.git/drivers/regulator/dummy.c, branch v6.12.80

regulator: dummy: force synchronous probing

2025-03-28T21:03:29+00:00

commit 8619909b38eeebd3e60910158d7d68441fc954e9 upstream. Sometimes I get a NULL pointer dereference at boot time in kobject_get() with the following call stack: anatop_regulator_probe() devm_regulator_register() regulator_register() regulator_resolve_supply() kobject_get() By placing some extra BUG_ON() statements I could verify that this is raised because probing of the 'dummy' regulator driver is not completed ('dummy_regulator_rdev' is still NULL). In the JTAG debugger I can see that dummy_regulator_probe() and anatop_regulator_probe() can be run by different kernel threads (kworker/u4:*). I haven't further investigated whether this can be changed or if there are other possibilities to force synchronization between these two probe routines. On the other hand I don't expect much boot time penalty by probing the 'dummy' regulator synchronously. Cc: stable@vger.kernel.org Fixes: 259b93b21a9f ("regulator: Set PROBE_PREFER_ASYNCHRONOUS for drivers that existed in 4.14") Signed-off-by: Christian Eggers Link: https://patch.msgid.link/20250311091803.31026-1-ceggers@arri.de Signed-off-by: Mark Brown Signed-off-by: Greg Kroah-Hartman

regulator: Set PROBE_PREFER_ASYNCHRONOUS for drivers that existed in 4.14

2023-03-20T13:11:25+00:00

Probing of regulators can be a slow operation and can contribute to slower boot times. This is especially true if a regulator is turned on at probe time (with regulator-boot-on or regulator-always-on) and the regulator requires delays (off-on-time, ramp time, etc). While the overall kernel is not ready to switch to async probe by default, as per the discussion on the mailing lists [1] it is believed that the regulator subsystem is in good shape and we can move regulator drivers over wholesale. There is no way to just magically opt in all regulators (regulators are just normal drivers like platform_driver), so we set PROBE_PREFER_ASYNCHRONOUS for all regulators found in 'drivers/regulator' individually. Given the number of drivers touched and the impossibility to test this ahead of time, it wouldn't be shocking at all if this caused a regression for someone. If there is a regression caused by this patch, it's likely to be one of the cases talked about in [1]. As a "quick fix", drivers involved in the regression could be fixed by changing them to PROBE_FORCE_SYNCHRONOUS. That being said, the correct fix would be to directly fix the problem that caused the issue with async probe. The approach here follows a similar approach that was used for the mmc subsystem several years ago [2]. In fact, I ran nearly the same python script to auto-generate the changes. The only thing I changed was to search for "i2c_driver", "spmi_driver", and "spi_driver" in addition to "platform_driver". [1] https://lore.kernel.org/r/06db017f-e985-4434-8d1d-02ca2100cca0@sirena.org.uk [2] https://lore.kernel.org/r/20200903232441.2694866-1-dianders@chromium.org/ Signed-off-by: Douglas Anderson Link: https://lore.kernel.org/r/20230316125351.1.I2a4677392a38db5758dee0788b2cea5872562a82@changeid Signed-off-by: Mark Brown

regulator: dummy: Use devm_regulator_register()

2021-09-27T12:01:20+00:00

debugfs code complained at boot time that debugfs: Directory 'reg-dummy-regulator-dummy' with parent 'regulator' already present! if we compile kernel with DEBUG_TEST_DRIVER_REMOVE. The problem is that we don't provide .remove() method for dummy_regulator_driver, which should invoke regulator_unregister() on device teardown to properly free things. Though it's harmless as dummy_pdev never gets unbound in practice, let's use devm_regulator_register() to get rid of the inconsistency. Signed-off-by: Zenghui Yu Link: https://lore.kernel.org/r/20210925035507.1904-1-yuzenghui@huawei.com Signed-off-by: Mark Brown

regulator: dummy: Constify dummy_initdata and dummy_ops

2020-09-14T13:24:36+00:00

The only usage of dummy_initdata is to assign its address to the init_data field of the regulator_config struct and the only usage dummy_ops is to assign its address to the ops field in the regulator_desc struct, both which are const pointers. Make them const to allow the compiler to put them in read-only memory. Signed-off-by: Rikard Falkeborn Link: https://lore.kernel.org/r/20200913084114.8851-2-rikard.falkeborn@gmail.com Signed-off-by: Mark Brown

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152

2019-05-30T18:26:32+00:00

Based on 1 normalized pattern(s): this program is free software you can redistribute it and or modify it under the terms of the gnu general public license as published by the free software foundation either version 2 of the license or at your option any later version extracted by the scancode license scanner the SPDX license identifier GPL-2.0-or-later has been chosen to replace the boilerplate/reference in 3029 file(s). Signed-off-by: Thomas Gleixner Reviewed-by: Allison Randal Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190527070032.746973796@linutronix.de Signed-off-by: Greg Kroah-Hartman

Merge tag 'driver-core-3.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core

2014-12-15T00:10:09+00:00

Pull driver core update from Greg KH: "Here's the set of driver core patches for 3.19-rc1. They are dominated by the removal of the .owner field in platform drivers. They touch a lot of files, but they are "simple" changes, just removing a line in a structure. Other than that, a few minor driver core and debugfs changes. There are some ath9k patches coming in through this tree that have been acked by the wireless maintainers as they relied on the debugfs changes. Everything has been in linux-next for a while" * tag 'driver-core-3.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (324 commits) Revert "ath: ath9k: use debugfs_create_devm_seqfile() helper for seq_file entries" fs: debugfs: add forward declaration for struct device type firmware class: Deletion of an unnecessary check before the function call "vunmap" firmware loader: fix hung task warning dump devcoredump: provide a one-way disable function device: Add dev__once variants ath: ath9k: use debugfs_create_devm_seqfile() helper for seq_file entries ath: use seq_file api for ath9k debugfs files debugfs: add helper function to create device related seq_file drivers/base: cacheinfo: remove noisy error boot message Revert "core: platform: add warning if driver has no owner" drivers: base: support cpu cache information interface to userspace via sysfs drivers: base: add cpu_device_create to support per-cpu devices topology: replace custom attribute macros with standard DEVICE_ATTR* cpumask: factor out show_cpumap into separate helper function driver core: Fix unbalanced device reference in drivers_probe driver core: fix race with userland in device_add() sysfs/kernfs: make read requests on pre-alloc files use the buffer. sysfs/kernfs: allow attributes to request write buffer be pre-allocated. fs: sysfs: return EGBIG on write if offset is larger than file size ...

regulator: dummy: Make regulator_desc array const

2014-10-28T00:01:44+00:00

The regulator_register() expects array of 'regulator_desc' to be const. Signed-off-by: Krzysztof Kozlowski Signed-off-by: Mark Brown

regulator: drop owner assignment from platform_drivers

2014-10-20T14:21:29+00:00

A platform_driver does not need to set an owner, it will be populated by the driver core. Signed-off-by: Wolfram Sang

regulator: dummy: Should be always-on

2014-02-25T23:49:52+00:00

Regulator dummy does not have any enable operations. So it is always_on. Signed-off-by: Markus Pargmann Signed-off-by: Mark Brown

regulator: remove use of __devinit

2012-11-20T01:31:26+00:00

CONFIG_HOTPLUG is going away as an option so __devinit is no longer needed. Signed-off-by: Bill Pemberton Signed-off-by: Mark Brown