From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Rafael J. Wysocki" Subject: Re: [RFC][PATCH 1/2] PM: Add support for device power domains Date: Mon, 14 Feb 2011 23:34:47 +0100 Message-ID: <201102142334.47553.rjw__7738.52352654121$1297857240$gmane$org@sisk.pl> References: Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: linux-pm-bounces@lists.linux-foundation.org Errors-To: linux-pm-bounces@lists.linux-foundation.org To: Alan Stern Cc: Mark Brown , LKML , Grant Likely , Linux-pm mailing list List-Id: linux-pm@vger.kernel.org On Monday, February 14, 2011, Alan Stern wrote: > On Sat, 12 Feb 2011, Rafael J. Wysocki wrote: > > > From: Rafael J. Wysocki > > > > The platform bus type is often used to handle Systems-on-a-Chip (SoC) > > where all devices are represented by objects of type struct > > platform_device. In those cases the same "platform" device driver > > may be used with multiple different system configurations, but the > > actions needed to put the devices it handles into a low-power state > > and back into the full-power state may depend on the design of the > > given SoC. The driver, however, cannot possibly include all the > > information necessary for the power management of its device on all > > the systems it is used with. Moreover, the device hierarchy in its > > current form also is not suitable for representing this kind of > > information. > > > > The patch below attempts to address this problem by introducing > > objects of type struct dev_power_domain that can be used for > > representing power domains within a SoC. Every struct > > dev_power_domain object provides a sets of device power > > management callbacks that can be used to perform what's needed for > > device power management in addition to the operations carried out by > > the device's driver and subsystem. > > > > Namely, if a struct dev_power_domain object is pointed to by the > > pwr_domain field in a struct device, the callbacks provided by its > > ops member will be executed in addition to the corresponding > > callbacks provided by the device's subsystem and driver during all > > power transitions. > > Overall this looks very good. > > > Index: linux-2.6/include/linux/pm.h > > =================================================================== > > --- linux-2.6.orig/include/linux/pm.h > > +++ linux-2.6/include/linux/pm.h > > @@ -463,6 +463,14 @@ struct dev_pm_info { > > > > extern void update_pm_runtime_accounting(struct device *dev); > > > > +/* > > + * Power domains provide callbacks that are executed during system suspend, > > + * hibernation, system resume and during runtime PM transitions along with > > + * subsystem-level and driver-level callbacks. > > + */ > > +struct dev_power_domain { > > + struct dev_pm_ops ops; > > +}; > > I don't have a clear picture of how people are going to want to use > these dev_power_domain structures. Should there be a > > void *priv; > > member as well? Well, I'm not sure. What would be the purpose of it? Rafael