vctrl_enable() and vctrl_disable() call regulator_enable() and
regulator_disable(), respectively. However, vctrl_* are regulator ops
and should not be calling the locked regulator APIs. Doing so results in
a lockdep warning.
Instead of exporting more internal regulator ops, model the ctrl supply
as an actual supply to vctrl-regulator. At probe time this driver still
needs to use the consumer API to fetch its constraints, but otherwise
lets the regulator core handle the upstream supply for it.
The enable/disable/is_enabled ops are not removed, but now only track
state internally. This preserves the original behavior with the ops
being available, but one could argue that the original behavior was
already incorrect: the internal state would not match the upstream
supply if that supply had another consumer that enabled the supply,
while vctrl-regulator was not enabled.
The lockdep warning is as follows:
WARNING: possible circular locking dependency detected
5.14.0-rc6 #2 Not tainted
------------------------------------------------------
swapper/0/1 is trying to acquire lock:
ffffffc011306d00 (regulator_list_mutex){+.+.}-{3:3}, at:
regulator_lock_dependent (arch/arm64/include/asm/current.h:19
include/linux/ww_mutex.h:111
drivers/regulator/core.c:329)
but task is already holding lock:
ffffff8004a77160 (regulator_ww_class_mutex){+.+.}-{3:3}, at:
regulator_lock_recursive (drivers/regulator/core.c:156
drivers/regulator/core.c:263)
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #2 (regulator_ww_class_mutex){+.+.}-{3:3}:
__mutex_lock_common (include/asm-generic/atomic-instrumented.h:606
include/asm-generic/atomic-long.h:29
kernel/locking/mutex.c:103
kernel/locking/mutex.c:144
kernel/locking/mutex.c:963)
ww_mutex_lock (kernel/locking/mutex.c:1199)
regulator_lock_recursive (drivers/regulator/core.c:156
drivers/regulator/core.c:263)
regulator_lock_dependent (drivers/regulator/core.c:343)
regulator_enable (drivers/regulator/core.c:2808)
set_machine_constraints (drivers/regulator/core.c:1536)
regulator_register (drivers/regulator/core.c:5486)
devm_regulator_register (drivers/regulator/devres.c:196)
reg_fixed_voltage_probe (drivers/regulator/fixed.c:289)
platform_probe (drivers/base/platform.c:1427)
[...]
-> #1 (regulator_ww_class_acquire){+.+.}-{0:0}:
regulator_lock_dependent (include/linux/ww_mutex.h:129
drivers/regulator/core.c:329)
regulator_enable (drivers/regulator/core.c:2808)
set_machine_constraints (drivers/regulator/core.c:1536)
regulator_register (drivers/regulator/core.c:5486)
devm_regulator_register (drivers/regulator/devres.c:196)
reg_fixed_voltage_probe (drivers/regulator/fixed.c:289)
[...]
-> #0 (regulator_list_mutex){+.+.}-{3:3}:
__lock_acquire (kernel/locking/lockdep.c:3052 (discriminator 4)
kernel/locking/lockdep.c:3174 (discriminator 4)
kernel/locking/lockdep.c:3789 (discriminator 4)
kernel/locking/lockdep.c:5015 (discriminator 4))
lock_acquire (arch/arm64/include/asm/percpu.h:39
kernel/locking/lockdep.c:438
kernel/locking/lockdep.c:5627)
__mutex_lock_common (include/asm-generic/atomic-instrumented.h:606
include/asm-generic/atomic-long.h:29
kernel/locking/mutex.c:103
kernel/locking/mutex.c:144
kernel/locking/mutex.c:963)
mutex_lock_nested (kernel/locking/mutex.c:1125)
regulator_lock_dependent (arch/arm64/include/asm/current.h:19
include/linux/ww_mutex.h:111
drivers/regulator/core.c:329)
regulator_enable (drivers/regulator/core.c:2808)
vctrl_enable (drivers/regulator/vctrl-regulator.c:400)
_regulator_do_enable (drivers/regulator/core.c:2617)
_regulator_enable (drivers/regulator/core.c:2764)
regulator_enable (drivers/regulator/core.c:308
drivers/regulator/core.c:2809)
_set_opp (drivers/opp/core.c:819 drivers/opp/core.c:1072)
dev_pm_opp_set_rate (drivers/opp/core.c:1164)
set_target (drivers/cpufreq/cpufreq-dt.c:62)
__cpufreq_driver_target (drivers/cpufreq/cpufreq.c:2216
drivers/cpufreq/cpufreq.c:2271)
cpufreq_online (drivers/cpufreq/cpufreq.c:1488 (discriminator 2))
cpufreq_add_dev (drivers/cpufreq/cpufreq.c:1563)
subsys_interface_register (drivers/base/bus.c:?)
cpufreq_register_driver (drivers/cpufreq/cpufreq.c:2819)
dt_cpufreq_probe (drivers/cpufreq/cpufreq-dt.c:344)
[...]
other info that might help us debug this:
Chain exists of:
regulator_list_mutex --> regulator_ww_class_acquire --> regulator_ww_class_mutex
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(regulator_ww_class_mutex);
lock(regulator_ww_class_acquire);
lock(regulator_ww_class_mutex);
lock(regulator_list_mutex);
*** DEADLOCK ***
6 locks held by swapper/0/1:
#0: ffffff8002d32188 (&dev->mutex){....}-{3:3}, at:
__device_driver_lock (drivers/base/dd.c:1030)
#1: ffffffc0111a0520 (cpu_hotplug_lock){++++}-{0:0}, at:
cpufreq_register_driver (drivers/cpufreq/cpufreq.c:2792 (discriminator 2))
#2: ffffff8002a8d918 (subsys mutex#9){+.+.}-{3:3}, at:
subsys_interface_register (drivers/base/bus.c:1033)
#3: ffffff800341bb90 (&policy->rwsem){+.+.}-{3:3}, at:
cpufreq_online (include/linux/bitmap.h:285
include/linux/cpumask.h:405
drivers/cpufreq/cpufreq.c:1399)
#4: ffffffc011f0b7b8 (regulator_ww_class_acquire){+.+.}-{0:0}, at:
regulator_enable (drivers/regulator/core.c:2808)
#5: ffffff8004a77160 (regulator_ww_class_mutex){+.+.}-{3:3}, at:
regulator_lock_recursive (drivers/regulator/core.c:156
drivers/regulator/core.c:263)
stack backtrace:
CPU: 1 PID: 1 Comm: swapper/0 Not tainted 5.14.0-rc6 #2 7c8f8996d021ed0f65271e6aeebf7999de74a9fa
Hardware name: Google Scarlet (DT)
Call trace:
dump_backtrace (arch/arm64/kernel/stacktrace.c:161)
show_stack (arch/arm64/kernel/stacktrace.c:218)
dump_stack_lvl (lib/dump_stack.c:106 (discriminator 2))
dump_stack (lib/dump_stack.c:113)
print_circular_bug (kernel/locking/lockdep.c:?)
check_noncircular (kernel/locking/lockdep.c:?)
__lock_acquire (kernel/locking/lockdep.c:3052 (discriminator 4)
kernel/locking/lockdep.c:3174 (discriminator 4)
kernel/locking/lockdep.c:3789 (discriminator 4)
kernel/locking/lockdep.c:5015 (discriminator 4))
lock_acquire (arch/arm64/include/asm/percpu.h:39
kernel/locking/lockdep.c:438
kernel/locking/lockdep.c:5627)
__mutex_lock_common (include/asm-generic/atomic-instrumented.h:606
include/asm-generic/atomic-long.h:29
kernel/locking/mutex.c:103
kernel/locking/mutex.c:144
kernel/locking/mutex.c:963)
mutex_lock_nested (kernel/locking/mutex.c:1125)
regulator_lock_dependent (arch/arm64/include/asm/current.h:19
include/linux/ww_mutex.h:111
drivers/regulator/core.c:329)
regulator_enable (drivers/regulator/core.c:2808)
vctrl_enable (drivers/regulator/vctrl-regulator.c:400)
_regulator_do_enable (drivers/regulator/core.c:2617)
_regulator_enable (drivers/regulator/core.c:2764)
regulator_enable (drivers/regulator/core.c:308
drivers/regulator/core.c:2809)
_set_opp (drivers/opp/core.c:819 drivers/opp/core.c:1072)
dev_pm_opp_set_rate (drivers/opp/core.c:1164)
set_target (drivers/cpufreq/cpufreq-dt.c:62)
__cpufreq_driver_target (drivers/cpufreq/cpufreq.c:2216
drivers/cpufreq/cpufreq.c:2271)
cpufreq_online (drivers/cpufreq/cpufreq.c:1488 (discriminator 2))
cpufreq_add_dev (drivers/cpufreq/cpufreq.c:1563)
subsys_interface_register (drivers/base/bus.c:?)
cpufreq_register_driver (drivers/cpufreq/cpufreq.c:2819)
dt_cpufreq_probe (drivers/cpufreq/cpufreq-dt.c:344)
[...]
Reported-by: Brian Norris <briannorris@chromium.org>
Fixes: f8702f9e4a ("regulator: core: Use ww_mutex for regulators locking")
Fixes: e915331149 ("regulator: vctrl-regulator: Avoid deadlock getting and setting the voltage")
Signed-off-by: Chen-Yu Tsai <wenst@chromium.org>
Link: https://lore.kernel.org/r/20210825033704.3307263-3-wenst@chromium.org
Signed-off-by: Mark Brown <broonie@kernel.org>
In commit e915331149 ("regulator: vctrl-regulator: Avoid deadlock getting
and setting the voltage"), all calls to get/set the voltage of the
control regulator were switched to unlocked versions to avoid deadlocks.
However, the call in the probe path is done without regulator locks
held. In this case the locked version should be used.
Switch back to the locked regulator_get_voltage() in the probe path to
avoid any mishaps.
Fixes: e915331149 ("regulator: vctrl-regulator: Avoid deadlock getting and setting the voltage")
Signed-off-by: Chen-Yu Tsai <wenst@chromium.org>
Link: https://lore.kernel.org/r/20210825033704.3307263-2-wenst@chromium.org
Signed-off-by: Mark Brown <broonie@kernel.org>
`cat /sys/kernel/debug/regulator/regulator_summary` ends on a deadlock
when you have a voltage controlled regulator (vctrl).
The problem is that the vctrl_get_voltage() and vctrl_set_voltage() calls the
regulator_get_voltage() and regulator_set_voltage() and that will try to lock
again the dependent regulators (the regulator supplying the control voltage).
Fix the issue by exporting the unlocked version of the regulator_get_voltage()
and regulator_set_voltage() API so drivers that need it, like the voltage
controlled regulator driver can use it.
Fixes: f8702f9e4a ("regulator: core: Use ww_mutex for regulators locking")
Reported-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Link: https://lore.kernel.org/r/20200116094543.2847321-1-enric.balletbo@collabora.com
Signed-off-by: Mark Brown <broonie@kernel.org>
Based on 1 normalized pattern(s):
this software is licensed under the terms of the gnu general public
license version 2 as published by the free software foundation and
may be copied distributed and modified under those terms this
program is distributed in the hope that it will be useful but
without any warranty without even the implied warranty of
merchantability or fitness for a particular purpose see the gnu
general public license for more details
extracted by the scancode license scanner the SPDX license identifier
GPL-2.0-only
has been chosen to replace the boilerplate/reference in 285 file(s).
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexios Zavras <alexios.zavras@intel.com>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190529141900.642774971@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Axel Lin <axel.lin@ingics.com>
Reviewed-by: Mukesh Ojha <mojha@codeaurora.org>
Reviewed-by: Matthias Kaehlcke <mka@chromium.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
Current code only allocates rdesc->n_voltages entries for vctrl->vtable.
Thus use rdesc->n_voltages instead of n_voltages in the for loop.
While at it, also switch to use devm_kcalloc instead of devm_kmalloc_array
+ __GFP_ZERO flag and fix the argument order.
Signed-off-by: Axel Lin <axel.lin@ingics.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
The output voltage of a voltage controlled regulator can be controlled
through the voltage of another regulator. The current version of this
driver assumes that the output voltage is a linear function of the control
voltage.
Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
Chen-Yu Tsai