kernel/drivers/base/power/main.c, branch linux-6.9.y

PM: sleep: Call dpm_async_fn() directly in each suspend phase

2024-02-05T13:28:54Z

Simplify the system-wide suspend of devices by invoking dpm_async_fn() directly from the main loop in each suspend phase instead of using an additional wrapper function for running it. No intentional functional impact. Signed-off-by: Rafael J. Wysocki Reviewed-by: Stanislaw Gruszka Reviewed-by: Ulf Hansson

PM: sleep: Move devices to new lists earlier in each suspend phase

2024-02-05T13:28:54Z

During a system-wide suspend of devices, dpm_noirq_suspend_devices(), dpm_suspend_late() and dpm_suspend() move devices from one list to another. They do it with each device after its PM callback in the given suspend phase has run or has been scheduled for asynchronous execution, in case it is deleted from the current list in the meantime. However, devices can be moved to a new list before invoking their PM callbacks (which usually is the case for the devices whose callbacks are executed asynchronously anyway), because doing so does not affect the ordering of that list. In either case, each device is moved to the new list after the previous device has been moved to it or gone away, and if a device is removed, it does not matter which list it is in at that point, because deleting an entry from a list does not change the ordering of the other entries in it. Accordingly, modify the functions mentioned above to move devices to new lists without waiting for their PM callbacks to run regardless of whether or not they run asynchronously. No intentional functional impact. Signed-off-by: Rafael J. Wysocki Reviewed-by: Stanislaw Gruszka Reviewed-by: Ulf Hansson

PM: sleep: Move some assignments from under a lock

2024-02-05T13:28:54Z

The async_error and pm_transition variables are set under dpm_list_mtx in multiple places in the system-wide device PM core code, which is unnecessary and confusing, so rearrange the code so that the variables in question are set before acquiring the lock. While at it, add some empty code lines around locking to improve the consistency of the code. No intentional functional impact. Signed-off-by: Rafael J. Wysocki Reviewed-by: Stanislaw Gruszka Reviewed-by: Ulf Hansson

PM: sleep: stats: Log errors right after running suspend callbacks

2024-02-05T13:28:54Z

The error logging and failure statistics updates are carried out in two places in each system-wide device suspend phase, which is unnecessary code duplication, so do that in one place in each phase, right after invoking device suspend callbacks. While at it, add "noirq" or "late" to the "async" string printed when the failing device callback in the "noirq" or "late" suspend phase, respectively, was run asynchronously. Signed-off-by: Rafael J. Wysocki Reviewed-by: Stanislaw Gruszka Reviewed-by: Ulf Hansson

PM: sleep: stats: Call dpm_save_failed_step() at most once per phase

2024-02-05T13:28:54Z

If the handling of two or more devices fails in one suspend-resume phase, it should be counted once in the statistics which is not guaranteed to happen during system-wide resume of devices due to the possible asynchronous execution of device callbacks. Address this by using the async_error static variable during system-wide device resume to indicate that there has been a device resume error and the given suspend-resume phase should be counted as failing. Signed-off-by: Rafael J. Wysocki Reviewed-by: Stanislaw Gruszka Reviewed-by: Ulf Hansson

PM: sleep: stats: Define suspend_stats next to the code using it

2024-02-05T13:28:19Z

It is not necessary to define struct suspend_stats in a header file and the suspend_stats variable in the core device system-wide PM code. They both can be defined in kernel/power/main.c, next to the sysfs and debugfs code accessing suspend_stats, which can be static. Modify the code in question in accordance with the above observation and replace the static inline functions manipulating suspend_stats with regular ones defined in kernel/power/main.c. While at it, move the enum suspend_stat_step to the end of suspend.h which is a more suitable place for it. No intentional functional impact. Signed-off-by: Rafael J. Wysocki Reviewed-by: Ulf Hansson

PM: sleep: stats: Use an array of step failure counters

2024-02-05T13:25:56Z

Instead of using a set of individual struct suspend_stats fields representing suspend step failure counters, use an array of counters indexed by enum suspend_stat_step for this purpose, which allows dpm_save_failed_step() to increment the appropriate counter automatically, so that its callers don't need to do that directly. It also allows suspend_stats_show() to carry out a loop over the counters array to print their values. Because the counters cannot become negative, use unsigned int for representing them. The only user-observable impact of this change is a different ordering of entries in the suspend_stats debugfs file which is not expected to matter. Signed-off-by: Rafael J. Wysocki Reviewed-by: Stanislaw Gruszka Reviewed-by: Ulf Hansson

PM: sleep: Relocate two device PM core functions

2024-01-26T18:38:36Z

Move is_async() and dpm_async_fn() in the PM core to a more suitable place. No functional impact. Signed-off-by: Rafael J. Wysocki Reviewed-by: Stanislaw Gruszka

PM: sleep: Simplify dpm_suspended_list walk in dpm_resume()

2024-01-26T18:38:36Z

Notice that devices can be moved to dpm_prepared_list before running their resume callbacks, in analogy with dpm_noirq_resume_devices() and dpm_resume_early(), because doing so will not affect the final ordering of that list. Namely, if a device is the first dpm_suspended_list entry while dpm_list_mtx is held, it has not been removed so far and it cannot be removed until dpm_list_mtx is released, so moving it to dpm_prepared_list at that point is valid. If it is removed later, while its resume callback is running, it will be deleted from dpm_prepared_list without changing the ordering of the other devices in that list. Accordingly, rearrange the while () loop in dpm_resume() to move devices to dpm_prepared_list before running their resume callbacks and implify the locking and device reference counting in it. No intentional functional impact. Signed-off-by: Rafael J. Wysocki Reviewed-by: Stanislaw Gruszka

PM: sleep: Restore asynchronous device resume optimization

2024-01-10T19:59:20Z

Before commit 7839d0078e0d ("PM: sleep: Fix possible deadlocks in core system-wide PM code"), the resume of devices that were allowed to resume asynchronously was scheduled before starting the resume of the other devices, so the former did not have to wait for the latter unless functional dependencies were present. Commit 7839d0078e0d removed that optimization in order to address a correctness issue, but it can be restored with the help of a new device power management flag, so do that now. Signed-off-by: Rafael J. Wysocki Reviewed-by: Stanislaw Gruszka