kernel/linux.git/drivers/cpuidle/driver.c, branch v6.19.11

cpuidle: Warn instead of bailing out if target residency check fails

2025-11-25T18:06:38+00:00

It turns out that the change in commit 76934e495cdc ("cpuidle: Add sanity check for exit latency and target residency") goes too far because there are systems in the field on which the check introduced by that commit does not pass. For this reason, change __cpuidle_driver_init() return type back to void and make it print a warning when the check mentioned above does not pass. Fixes: 76934e495cdc ("cpuidle: Add sanity check for exit latency and target residency") Reported-by: Val Packett Closes: https://lore.kernel.org/linux-pm/20251121010756.6687-1-val@packett.cool/ Signed-off-by: Rafael J. Wysocki Reviewed-by: Christian Loehle Link: https://patch.msgid.link/2808566.mvXUDI8C0e@rafael.j.wysocki

cpuidle: Add sanity check for exit latency and target residency

2025-11-12T20:00:00+00:00

Make __cpuidle_driver_init() fail if the exit latency of one of the driver's idle states is less than its target residency which would break cpuidle assumptions. Signed-off-by: Rafael J. Wysocki Reviewed-by: Artem Bityutskiy Reviewed-by: Christian Loehle [ rjw: Changelog fix ] Link: https://patch.msgid.link/12779486.O9o76ZdvQC@rafael.j.wysocki Signed-off-by: Rafael J. Wysocki

cpuidle: Correct some typos in comments

2024-10-18T16:44:32+00:00

Fixed some confusing typos that were currently identified with codespell, the details are as follows: -in the code comments: drivers/cpuidle/cpuidle-arm.c:142: registeration ==> registration drivers/cpuidle/cpuidle-qcom-spm.c:51: accidently ==> accidentally drivers/cpuidle/cpuidle.c:409: dependant ==> dependent drivers/cpuidle/driver.c:264: occuring ==> occurring drivers/cpuidle/driver.c:299: occuring ==> occurring Signed-off-by: Shen Lichuan Link: https://patch.msgid.link/20240927081018.8608-1-shenlichuan@vivo.com Signed-off-by: Rafael J. Wysocki

cpuidle: Avoid potential overflow in integer multiplication

2024-02-12T16:07:49+00:00

In detail: In C language, when you perform a multiplication operation, if both operands are of int type, the multiplication operation is performed on the int type, and then the result is converted to the target type. This means that if the product of int type multiplication exceeds the range that int type can represent, an overflow will occur even if you store the result in a variable of int64_t type. For a multiplication of two int values, it is better to use mul_u32_u32() rather than s->exit_latency_ns = s->exit_latency * NSEC_PER_USEC to avoid potential overflow happenning. Signed-off-by: C Cheng Signed-off-by: Bo Ye Reviewed-by: AngeloGioacchino Del Regno [ rjw: New subject ] Signed-off-by: Rafael J. Wysocki

cpuidle: driver: Update microsecond values of state parameters as needed

2023-02-13T15:08:44+00:00

If the cpuidle driver provides the target residency and exit latency in nanoseconds, the corresponding values in microseconds need to be set to reflect the provided numbers in order for the sysfs interface to show them correctly, so make __cpuidle_driver_init() do that. Signed-off-by: Rafael J. Wysocki Tested-by: Artem Bityutskiy

cpuidle: Use s64 as exit_latency_ns and target_residency_ns data type

2021-04-07T17:26:44+00:00

Subsequent changes will cause the exit_latency_ns and target_residency_ns fields in struct cpuidle_state to be used in computations in which data type conversions to u64 may turn a negative number close to zero into a verly large positive number leading to incorrect results. In preparation for that, change the data type of the fields mentioned above to s64, but ensure that they will not be negative themselves. No intentional functional impact. Signed-off-by: Rafael J. Wysocki

cpuidle: Drop unused cpuidle_driver_ref/unref() functions

2020-01-09T15:47:22+00:00

The cpuidle_driver_ref() and cpuidle_driver_unref() functions are not used and the refcnt field in struct cpuidle_driver operated by them is not updated anywhere else (so it is permanently equal to 0), so drop both of them along with refcnt. Signed-off-by: Rafael J. Wysocki Acked-by: Daniel Lezcano

cpuidle: Fix cpuidle_driver_state_disabled()

2019-12-10T22:41:20+00:00

It turns out that cpuidle_driver_state_disabled() can be called before registering the cpufreq driver on some platforms, which was not expected when it was introduced and which leads to a NULL pointer dereference when trying to walk the CPUs associated with the given cpuidle driver. Fix the problem by making cpuidle_driver_state_disabled() check if the driver's mask of CPUs associated with it is present and to set CPUIDLE_FLAG_UNUSABLE for the given idle state in the driver's states list if that is not the case to cause __cpuidle_register_device() to set CPUIDLE_STATE_DISABLED_BY_DRIVER for that state for all cpuidle devices registered by it later. Fixes: cbda56d5fefc ("cpuidle: Introduce cpuidle_driver_state_disabled() for driver quirks") Reported-by: Daniel Lezcano Tested-by: Daniel Lezcano Signed-off-by: Rafael J. Wysocki

cpuidle: Introduce cpuidle_driver_state_disabled() for driver quirks

2019-11-19T09:35:13+00:00

Commit 99e98d3fb100 ("cpuidle: Consolidate disabled state checks") overlooked the fact that the imx6q and tegra20 cpuidle drivers use the "disabled" field in struct cpuidle_state for quirks which trigger after the initialization of cpuidle, so reading the initial value of that field is not sufficient for those drivers. In order to allow them to implement the quirks without using the "disabled" field in struct cpuidle_state, introduce a new helper function and modify them to use it. Fixes: 99e98d3fb100 ("cpuidle: Consolidate disabled state checks") Reported-by: Len Brown Signed-off-by: Rafael J. Wysocki

cpuidle: Use nanoseconds as the unit of time

2019-11-11T20:56:07+00:00

Currently, the cpuidle subsystem uses microseconds as the unit of time which (among other things) causes the idle loop to incur some integer division overhead for no clear benefit. In order to allow cpuidle to measure time in nanoseconds, add two new fields, exit_latency_ns and target_residency_ns, to represent the exit latency and target residency of an idle state in nanoseconds, respectively, to struct cpuidle_state and initialize them with the help of the corresponding values in microseconds provided by drivers. Additionally, change cpuidle_governor_latency_req() to return the idle state exit latency constraint in nanoseconds. Also meeasure idle state residency (last_residency_ns in struct cpuidle_device and time_ns in struct cpuidle_driver) in nanoseconds and update the cpuidle core and governors accordingly. However, the menu governor still computes typical intervals in microseconds to avoid integer overflows. Signed-off-by: Rafael J. Wysocki Acked-by: Peter Zijlstra (Intel) Acked-by: Doug Smythies Tested-by: Doug Smythies