Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S938783AbcKPKsp (ORCPT ); Wed, 16 Nov 2016 05:48:45 -0500 Received: from hqemgate16.nvidia.com ([216.228.121.65]:16514 "EHLO hqemgate16.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752713AbcKPKsm (ORCPT ); Wed, 16 Nov 2016 05:48:42 -0500 X-PGP-Universal: processed; by hqpgpgate101.nvidia.com on Wed, 16 Nov 2016 02:48:40 -0800 Subject: Re: [RFC PATCH 0/3] PM / Domains: Add support for devices that require multiple domains To: Ulf Hansson , Kevin Hilman References: <1474367287-10402-1-git-send-email-jonathanh@nvidia.com> <90faea7d-65b6-590a-83f1-24fcdffa0569@nvidia.com> <63670abf-1d58-a7e3-6927-0c815d44d8a1@nvidia.com> CC: "Rafael J. Wysocki" , "linux-pm@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-tegra@vger.kernel.org" , Rajendra Nayak From: Jon Hunter Message-ID: Date: Wed, 16 Nov 2016 10:48:29 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.4.0 MIME-Version: 1.0 In-Reply-To: <63670abf-1d58-a7e3-6927-0c815d44d8a1@nvidia.com> X-Originating-IP: [10.21.132.110] X-ClientProxiedBy: DRUKMAIL102.nvidia.com (10.25.59.20) To UKMAIL101.nvidia.com (10.26.138.13) Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2908 Lines: 71 Hi Kevin, Ulf, On 03/11/16 14:20, Jon Hunter wrote: > > On 11/10/16 10:15, Jon Hunter wrote: > > ... > >>>>> Second, another way of seeing this is: Depending on the current >>>>> runtime selected configuration you need to re-configure the PM domain >>>>> topology - but the device would still remain in the same PM domain. >>>>> >>>>> In other words, you would need to remove/add subdomain(s) depending on >>>>> the selected configuration. Would that better reflect the HW? >>>> >>>> I am not 100% sure I follow what you are saying, but ultimately, I would >>>> like to get to ... >>>> >>>> usb@70090000 { >>>> compatible = "nvidia,tegra210-xusb"; >>>> ... >>>> power-domains = <&pd_xusbhost>, <&pd_xusbss>; >>>> }; >>> >>> So, is this really is a proper description of the HW? Isn't it so, >>> that the usb device always resides in one and the same PM domain? >> >> I guess technically, the usbhost controller resides in one partition and >> the super-speed logic in another. So could the usbhost domain be the >> primary? Possibly, but the device cannot be probed without both enabled. >> >>> Now, depending on the selected speed mode (superspeed) additional >>> logic may needs to be powered on and configured for the usb device to >>> work? >>> Perhaps, one could consider those additional logics as a master/parent >>> PM domain for the usb device's PM domain? >>> >>> Or this is not how the HW works? :-) >> >> It might be possible for this case, but to be honest, the more I think >> about this, I do wonder if we need to be able to make the framework a >> lot more flexible for devices that need multiple power-domains. In other >> words, for devices that use multiple domains allow them to control them >> similarly to what we do for regulators or clocks. So if there is more >> than one defined, then the genpd core will not bind the device to the >> pm-domain and let the driver handle it. This way if you do need more >> granular control of the pm-domains in the driver you can do whatever you >> need to. >> >> I know that Rajendra (CC'ed) was looking into whether he had a need to >> control multiple power-domains individually from within the context of a >> single device driver. > > So Rajendra commented to say that he does not see a need for individual > control of power-domains for now, but a need for specifying multiple. > > One simple option would be to allow users to specify multiple and have > the genpd core effectively ignore such devices and leave it to the > driver to configure manually. I have been able to do this for XUSB by > dynamically adding power-domains to the device. > > Let me know if you have any more thoughts on how we can do this. Any more thoughts on this? Seems that there are a few others that would be interested in supporting multiple domains for a device. Cheers Jon -- nvpublic