Hi, On Mon, Oct 27, 2014 at 08:55:07AM -0700, Guenter Roeck wrote: > Various drivers implement architecture and/or device specific means to > remove power from the system. For the most part, those drivers set the > global variable pm_power_off to point to a function within the driver. > > This mechanism has a number of drawbacks. Typically only one means > to remove power is supported (at least if pm_power_off is used). > At least in theory there can be multiple means to remove power, some of > which may be less desirable. For example, one mechanism might power off the > entire system through an I/O port or gpio pin, while another might power off > a board by disabling its power controller. Other mechanisms may really just > execute a restart sequence or drop into the ROM monitor, or put the CPU into > sleep mode. Using pm_power_off can also be racy if the function pointer is > set from a driver built as module, as the driver may be in the process of > being unloaded when pm_power_off is called. If there are multiple power-off > handlers in the system, removing a module with such a handler may > inadvertently reset the pointer to pm_power_off to NULL, leaving the system > with no means to remove power. > > Introduce a system power-off handler call chain to solve the described > problems. This call chain is expected to be executed from the architecture > specific machine_power_off() function. Drivers providing system power-off > functionality are expected to register with this call chain. By using the > priority field in the notifier block, callers can control power-off handler > execution sequence and thus ensure that the power-off handler with the > optimal capabilities to remove power for a given system is called first. > A call chain instead of a single call to the highest priority handler is > used to provide fallback: If multiple power-off handlers are installed, > all handlers will be called until one actually succeeds to power off the > system. > > Patch 01/47 implements the power-off handler API. > > Patches 02/47 to 04/47 are cleanup patches to prepare for the move of > pm_power_off to a common location. > > Patches 05/47 to 07/47 remove references to pm_power_off from devicetree > bindings descriptions. > > Patch 08/47 moves the pm_power_off variable from architecture code to > kernel/reboot.c. > > Patches 09/47 to 34/47 convert various drivers to register with the kernel > power-off handler instead of setting pm_power_off directly. > > Patches 35/47 to 46/47 do the same for architecture code. > > Patch 47/47 finally removes pm_power_off. > > For the most part, the individual patches include explanations why specific > priorities were chosen, at least if the selected priority is not the default > priority. Subsystem and architecture maintainers are encouraged to have a look > at the selected priorities and suggest improvements. > > I ran the final code through my normal build and qemu tests. Results are > available at http://server.roeck-us.net:8010/builders in the > 'poweroff-handler' > column. I also built all available configurations for arm, mips, powerpc, > m68k, and sh architectures. > > The series is available in branch poweroff-handler of my repository at > git://git.kernel.org/pub/scm/linux/kernel/git/groeck/linux-staging.git. > It is based on 3.18-rc2. > > A note on Cc: In the initial submission I had way too many Cc:, causing the > patchset to be treated as spam by many mailers and mailing list handlers, > which of course defeated the purpose. This time around I am cutting down > the distribution list down significantly. My apologies to anyone I may have > failed to copy this time around.
you touch every single architecture with this patchset, but you didn't care about Ccing any of the arch-specific mailing lists, like lakml ? Please resend with proper people in Cc, IIRC RMK had a few very important comments about the idea behind this series. > Important changes since v2: > - Rebased series to v3.18-rc2. > - Do not hold any locks while executing the power-off call chain. > This ensures that power-off handlers are executed in the state > selected by the machine_power_off function for a given architecture, > ie without changing the current semantics of power-off callbacks and > machine_power_off functions. > Power-off handler registration and de-registration is handled in atomic > context with interrupts disabled to ensure that those functions are not > interrupted by code which powers off the system. > - Use [xxx_]power_off[_xxx] instead of [xxx_]poweroff[_xxx] for newly > introduced function and variable names. > - Use power-off instead of poweroff in descriptive text and comments. > - Replace POWEROFF_PRIORITY_xxx with POWER_OFF_PRIORITY_xxx > - Use ACPI: instead of acpi: for messages in acpi code. > > Important changes since v1: > - Rebased series to v3.18-rc1. > - Use raw notifier with spinlock protection instead of atomic notifiers, > since some power-off handlers need to have interrupts enabled. > - Renamed API functions from _poweroff to _power_off. > - Added various Acks. > - Build tested all configurations for arm, powerpc, and mips architectures. > - Fixed two compile errors in mips patch. > - Replaced dev_err and pr_err with dev_warn and pr_warn if an error is not > fatal. > - Provide managed resources API and use where appropriate. > - Provide and use definitions for standard priorities. > - Added patches to convert newly introduced power-off handlers. > - Various minor changes. > > Important changes since RFC: > - Move API to new file kernel/power/power_off_handler.c. > - Move pm_power_off pointer to kernel/power/power_off_handler.c. Call > pm_power_off from do_kernel_power_off, and only call do_kernel_power_off > from architecture code instead of calling both pm_power_off and > do_kernel_power_off. > - Provide additional API function register_power_off_handler_simple > to simplify conversion of architecture code. > - Provide additional API function have_kernel_power_off to check if > a power-off handler was installed. > - Convert all drivers and architecture code to use the new API. > - Remove pm_power_off as last patch of the series. > > Cc: Alan Cox <gno...@lxorguk.ukuu.org.uk> > Cc: Alexander Graf <ag...@suse.de> > Cc: Andrew Morton <a...@linux-foundation.org> > Cc: Geert Uytterhoeven <ge...@linux-m68k.org> > cc: Heiko Stuebner <he...@sntech.de> > Cc: Lee Jones <lee.jo...@linaro.org> > Cc: Len Brown <len.br...@intel.com> > Cc: Pavel Machek <pa...@ucw.cz> > Cc: Rafael J. Wysocki <r...@rjwysocki.net> > Cc: Romain Perier <romain.per...@gmail.com> > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majord...@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ -- balbi
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