From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S970967AbeEXPtC (ORCPT ); Thu, 24 May 2018 11:49:02 -0400 Received: from hqemgate15.nvidia.com ([216.228.121.64]:5349 "EHLO hqemgate15.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S966676AbeEXPs7 (ORCPT ); Thu, 24 May 2018 11:48:59 -0400 X-PGP-Universal: processed; by hqpgpgate101.nvidia.com on Thu, 24 May 2018 08:48:59 -0700 Subject: Re: [PATCH 9/9] PM / Domains: Add dev_pm_domain_attach_by_id() to manage multi PM domains To: Ulf Hansson , "Rafael J . Wysocki" , CC: Greg Kroah-Hartman , Geert Uytterhoeven , Todor Tomov , "Rajendra Nayak" , Viresh Kumar , Vincent Guittot , Kevin Hilman , , , References: <1526639490-12167-1-git-send-email-ulf.hansson@linaro.org> <1526639490-12167-10-git-send-email-ulf.hansson@linaro.org> From: Jon Hunter Message-ID: <1c21d18e-954a-f3a8-9817-0117b7cb7e4f@nvidia.com> Date: Thu, 24 May 2018 16:48:53 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.7.0 MIME-Version: 1.0 In-Reply-To: <1526639490-12167-10-git-send-email-ulf.hansson@linaro.org> X-Originating-IP: [172.20.13.39] X-ClientProxiedBy: HQMAIL103.nvidia.com (172.20.187.11) To HQMAIL102.nvidia.com (172.18.146.10) Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 18/05/18 11:31, Ulf Hansson wrote: > The existing dev_pm_domain_attach() function, allows a single PM domain to > be attached per device. To be able to support devices that are partitioned > across multiple PM domains, let's introduce a new interface, > dev_pm_domain_attach_by_id(). > > The dev_pm_domain_attach_by_id() returns a new allocated struct device with > the corresponding attached PM domain. This enables for example a driver to > operate on the new device from a power management point of view. The driver > may then also benefit from using the received device, to set up so called > device-links towards its original device. Depending on the situation, these > links may then be dynamically changed. > > The new interface is typically called by drivers during their probe phase, > in case they manages devices which uses multiple PM domains. If that is the > case, the driver also becomes responsible of managing the detaching of the > PM domains, which typically should be done at the remove phase. Detaching > is done by calling the existing dev_pm_domain_detach() function and for > each of the received devices from dev_pm_domain_attach_by_id(). > > Note, currently its only genpd that supports multiple PM domains per > device, but dev_pm_domain_attach_by_id() can easily by extended to cover > other PM domain types, if/when needed. > > Signed-off-by: Ulf Hansson > --- > drivers/base/power/common.c | 33 ++++++++++++++++++++++++++++++++- > include/linux/pm_domain.h | 7 +++++++ > 2 files changed, 39 insertions(+), 1 deletion(-) > > diff --git a/drivers/base/power/common.c b/drivers/base/power/common.c > index 7ae62b6..d3db974 100644 > --- a/drivers/base/power/common.c > +++ b/drivers/base/power/common.c > @@ -117,13 +117,44 @@ int dev_pm_domain_attach(struct device *dev, bool power_on) > EXPORT_SYMBOL_GPL(dev_pm_domain_attach); > > /** > + * dev_pm_domain_attach_by_id - Attach a device to one of its PM domains. Isn't this more of a 'get'? > + * @index: The index of the PM domain. > + * @dev: Device to attach. Isn't this just the device associated with the PM domain we are getting? > + * > + * As @dev may only be attached to a single PM domain, the backend PM domain > + * provider should create a virtual device to attach instead. As attachment > + * succeeds, the ->detach() callback in the struct dev_pm_domain should be > + * assigned by the corresponding backend attach function. > + * > + * This function should typically be invoked from drivers during probe phase. > + * Especially for those that manages devices which requires power management > + * through more than one PM domain. > + * > + * Callers must ensure proper synchronization of this function with power > + * management callbacks. > + * > + * Returns the virtual attached device in case successfully attached PM domain, > + * NULL in case @dev don't need a PM domain, else a PTR_ERR(). Should this be 'NULL in the case where the @dev already has a power-domain'? > + */ > +struct device *dev_pm_domain_attach_by_id(struct device *dev, > + unsigned int index) > +{ > + if (dev->pm_domain) I wonder if this is worthy of a ... if (WARN_ON(dev->pm_domain)) > + return NULL; Don't we consider this an error case? I wonder why not return PTR_ERR here as well? This would be consistent with dev_pm_domain_attach(). Cheers Jon -- nvpublic