Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751921Ab1FKUkh (ORCPT ); Sat, 11 Jun 2011 16:40:37 -0400 Received: from ogre.sisk.pl ([217.79.144.158]:48635 "EHLO ogre.sisk.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751552Ab1FKUkf (ORCPT ); Sat, 11 Jun 2011 16:40:35 -0400 From: "Rafael J. Wysocki" To: Linux PM mailing list Subject: [PATCH 1/8] PM / Domains: Update documentation Date: Sat, 11 Jun 2011 22:25:18 +0200 User-Agent: KMail/1.13.6 (Linux/2.6.39+; KDE/4.6.0; x86_64; ; ) Cc: "Greg Kroah-Hartman" , Magnus Damm , Paul Walmsley , Kevin Hilman , Alan Stern , LKML , linux-sh@vger.kernel.org References: <201106112223.04972.rjw@sisk.pl> In-Reply-To: <201106112223.04972.rjw@sisk.pl> MIME-Version: 1.0 Content-Type: Text/Plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <201106112225.18266.rjw@sisk.pl> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4099 Lines: 69 From: Rafael J. Wysocki Commit 4d27e9dcff00a6425d779b065ec8892e4f391661 (PM: Make power domain callbacks take precedence over subsystem ones) forgot to update the device power management documentation to take changes made by it into account. Correct that mistake. Signed-off-by: Rafael J. Wysocki --- Documentation/power/devices.txt | 39 +++++++++++++-------------------------- 1 file changed, 13 insertions(+), 26 deletions(-) Index: linux-2.6/Documentation/power/devices.txt =================================================================== --- linux-2.6.orig/Documentation/power/devices.txt +++ linux-2.6/Documentation/power/devices.txt @@ -520,33 +520,20 @@ Support for power domains is provided th device. This field is a pointer to an object of type struct dev_power_domain, defined in include/linux/pm.h, providing a set of power management callbacks analogous to the subsystem-level and device driver callbacks that are executed -for the given device during all power transitions, in addition to the respective -subsystem-level callbacks. Specifically, the power domain "suspend" callbacks -(i.e. ->runtime_suspend(), ->suspend(), ->freeze(), ->poweroff(), etc.) are -executed after the analogous subsystem-level callbacks, while the power domain -"resume" callbacks (i.e. ->runtime_resume(), ->resume(), ->thaw(), ->restore, -etc.) are executed before the analogous subsystem-level callbacks. Error codes -returned by the "suspend" and "resume" power domain callbacks are ignored. +for the given device during all power transitions, instead of the respective +subsystem-level callbacks. Specifically, if a device's pm_domain pointer is +not NULL, the ->suspend() callback from the object pointed to by it will be +executed instead of its subsystem's (e.g. bus type's) ->suspend() callback and +anlogously for all of the remaining callbacks. In other words, power management +domain callbacks, if defined for the given device, always take precedence over +the callbacks provided by the device's subsystem (e.g. bus type). -Power domain ->runtime_idle() callback is executed before the subsystem-level -->runtime_idle() callback and the result returned by it is not ignored. Namely, -if it returns error code, the subsystem-level ->runtime_idle() callback will not -be called and the helper function rpm_idle() executing it will return error -code. This mechanism is intended to help platforms where saving device state -is a time consuming operation and should only be carried out if all devices -in the power domain are idle, before turning off the shared power resource(s). -Namely, the power domain ->runtime_idle() callback may return error code until -the pm_runtime_idle() helper (or its asychronous version) has been called for -all devices in the power domain (it is recommended that the returned error code -be -EBUSY in those cases), preventing the subsystem-level ->runtime_idle() -callback from being run prematurely. - -The support for device power domains is only relevant to platforms needing to -use the same subsystem-level (e.g. platform bus type) and device driver power -management callbacks in many different power domain configurations and wanting -to avoid incorporating the support for power domains into the subsystem-level -callbacks. The other platforms need not implement it or take it into account -in any way. +The support for device power management domains is only relevant to platforms +needing to use the same device driver power management callbacks in many +different power domain configurations and wanting to avoid incorporating the +support for power domains into subsystem-level callbacks, for example by +modifying the platform bus type. Other platforms need not implement it or take +it into account in any way. Device Low Power (suspend) States -- 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/