On Fri, Nov 26, 2021 at 09:00:44PM +0300, Dmitry Osipenko wrote: > SoC platforms often have multiple ways of how to perform system's > power-off and restart operations. Meanwhile today's kernel is limited to > a single option. Add combined power-off+restart handler call chain API, > which is inspired by the restart API. The new API provides both power-off > and restart functionality. > > The old pm_power_off method will be kept around till all users are > converted to the new API. > > Current restart API will be replaced by the new unified API since > new API is its superset. The restart functionality of the sys-off handler > API is built upon the existing restart-notifier APIs. > > In order to ease conversion to the new API, convenient helpers are added > for the common use-cases. They will reduce amount of boilerplate code and > remove global variables. These helpers preserve old behaviour for cases > where only one power-off handler is expected, this is what all existing > drivers want, and thus, they could be easily converted to the new API. > Users of the new API should explicitly enable power-off chaining by > setting corresponding flag of the power_handler structure. [...] Hi, A general question: do we really need three distinct chains for this? Can't there be only one that chain of callbacks that get a stage (RESTART_PREPARE, RESTART, POWER_OFF_PREPARE, POWER_OFF) and can ignore them at will? Calling through POWER_OFF_PREPARE would also return whether that POWER_OFF is possible (for kernel_can_power_off()). I would also split this patch into preparation cleanups (like wrapping pm_power_off call with a function) and adding the notifier-based implementation. Best Regards Michał Mirosław
