From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752963AbaJ0QEa (ORCPT ); Mon, 27 Oct 2014 12:04:30 -0400 Received: from devils.ext.ti.com ([198.47.26.153]:59390 "EHLO devils.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751998AbaJ0QE1 (ORCPT ); Mon, 27 Oct 2014 12:04:27 -0400 Date: Mon, 27 Oct 2014 11:03:24 -0500 From: Felipe Balbi To: Guenter Roeck CC: , , Alan Cox , Alexander Graf , Andrew Morton , Geert Uytterhoeven , Heiko Stuebner , Lee Jones , Len Brown , Pavel Machek , "Rafael J. Wysocki" , Romain Perier , Johan Hovold Subject: Re: [PATCH v3 00/47] kernel: Add support for power-off handler call chain Message-ID: <20141027160324.GD10814@saruman> Reply-To: References: <1414425354-10359-1-git-send-email-linux@roeck-us.net> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="3Pql8miugIZX0722" Content-Disposition: inline In-Reply-To: <1414425354-10359-1-git-send-email-linux@roeck-us.net> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --3Pql8miugIZX0722 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Adding Johan, who's working on RTC power off for AM335x devices 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. >=20 > 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 ju= st > execute a restart sequence or drop into the ROM monitor, or put the CPU i= nto > 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 syst= em > with no means to remove power. >=20 > Introduce a system power-off handler call chain to solve the described > problems. This call chain is expected to be executed from the architectu= re > 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 handl= er > 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. >=20 > Patch 01/47 implements the power-off handler API. >=20 > Patches 02/47 to 04/47 are cleanup patches to prepare for the move of > pm_power_off to a common location. >=20 > Patches 05/47 to 07/47 remove references to pm_power_off from devicetree > bindings descriptions. >=20 > Patch 08/47 moves the pm_power_off variable from architecture code to > kernel/reboot.c.=20 >=20 > Patches 09/47 to 34/47 convert various drivers to register with the kernel > power-off handler instead of setting pm_power_off directly. >=20 > Patches 35/47 to 46/47 do the same for architecture code. >=20 > Patch 47/47 finally removes pm_power_off. >=20 > For the most part, the individual patches include explanations why specif= ic > priorities were chosen, at least if the selected priority is not the defa= ult > priority. Subsystem and architecture maintainers are encouraged to have a= look > at the selected priorities and suggest improvements. >=20 > 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-ha= ndler' > column. I also built all available configurations for arm, mips, powerpc, > m68k, and sh architectures. >=20 > 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. >=20 > A note on Cc: In the initial submission I had way too many Cc:, causing t= he > 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 ha= ve > failed to copy this time around. >=20 > 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. >=20 > 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 architecture= s. > - 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. >=20 > 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. >=20 > Cc: Alan Cox > Cc: Alexander Graf > Cc: Andrew Morton > Cc: Geert Uytterhoeven > cc: Heiko Stuebner > Cc: Lee Jones > Cc: Len Brown > Cc: Pavel Machek > Cc: Rafael J. Wysocki > Cc: Romain Perier > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ --=20 balbi --3Pql8miugIZX0722 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQIcBAEBAgAGBQJUTmzMAAoJEIaOsuA1yqRExOcP/23YMnGVJWKRZhcYX22hGVJz EAf56161IaAZbulj/SPxRAj0rBLo4fskag9e+XxxI744g6F8FkIduIu6I+PeSm1+ 9eHgnt3HE5DUL/u77QrgHxix2DhxGN9cu5QiMGz8VQ/PXcheVhFkQftZQgDQ9625 FUTJiI0BoFIBnJFGM9mjM3Ff19dhbJ9+wcoy26MvInXBH9HBNaFDvLFJM+wzXFoV wkSmNQ/feMvcbpVlf6VmzzG1IfQP/0tEoYRZRcr+Ml412X80X1Pm951Xl4HoOI1T Mjk1DBdqOF67loFeoT/oOOlqY1yozyp/0yCT7LdZIqWUkHAoxqU1k2SNQ2Rd4QQC LT6TsgLwbCb/2UlpqhhIBHQharAI0CFwElxhdy2VCV3+4KQYHnZmOeVc70JWIHM4 8WxA7NuXMNaPytR3SzoxZSg2d+FGLtsy8slQXGDX6A3Y6ehLLCPY2xYZ+sU5c8cb se7SS8fYkp2wcx77TgMAu1n96aqFqiCviXxtEEDdLG1d0hZgtb1gzXV+3fejn+qC tf1UKTXNLI9u/ribMKoNeEG5PGpuKh6FEte85DH7CaA+tUSy+sg7grLYMVBmQTtW QkJzp09wczObD9fW4DvSxLnlztsTUGZRjyz/s/E/Sf5swWedj/gaO73pBy+1dYxu 8pvXU4UHPh/u+mJYKw6J =Y8HG -----END PGP SIGNATURE----- --3Pql8miugIZX0722--