From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754215AbeEaJOQ (ORCPT ); Thu, 31 May 2018 05:14:16 -0400 Received: from mail-pl0-f65.google.com ([209.85.160.65]:42910 "EHLO mail-pl0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754104AbeEaJON (ORCPT ); Thu, 31 May 2018 05:14:13 -0400 X-Google-Smtp-Source: ADUXVKIcsnN4OWe14aSUlLqCZm32HVOtfdEc1MKm2ePivkZBhdx/tURdkWBJPUUKXutuCJwVCLEXRg== Date: Thu, 31 May 2018 14:44:10 +0530 From: Viresh Kumar To: Ulf Hansson Cc: "Rafael J . Wysocki" , linux-pm@vger.kernel.org, Greg Kroah-Hartman , Jon Hunter , Geert Uytterhoeven , Todor Tomov , Rajendra Nayak , Vincent Guittot , Kevin Hilman , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-tegra@vger.kernel.org Subject: Re: [PATCH v2 0/9] PM / Domains: Add support for multi PM domains per device Message-ID: <20180531091410.fl5f42zmyqi6zj5a@vireshk-i7> References: <20180529100421.31022-1-ulf.hansson@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180529100421.31022-1-ulf.hansson@linaro.org> User-Agent: NeoMutt/20180323-120-3dd1ac Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 29-05-18, 12:04, Ulf Hansson wrote: > Changes in v2: > - Addressed comments from Geert around DT doc. > - Addressed comments from Jon around clarification of how to use this > and changes to returned error codes. > - Fixed build error in case CONFIG_PM was unset. > > There are devices that are partitioned across multiple PM domains. Currently > these can't be supported well by the available PM infrastructures we have in > the kernel. This series is an attempt to address this. > > The interesting parts happens from patch 5 an onwards, including a minor DT > update to the existing power-domain bindings, the 4 earlier are just trivial > clean-ups of some related code in genpd, which I happened to stumble over. > > Some additional background: > > One existing case where devices are partitioned across multiple PM domains, is > the Nvida Tegra 124/210 X-USB subsystem. A while ago Jon Hunter (Nvidia) sent a > series, trying to address these issues, however this is a new approach, while > it re-uses the same concepts from DT point of view. > > The Tegra 124/210 X-USB subsystem contains of a host controller and a device > controller. Each controller have its own independent PM domain, but are being > partitioned across another shared PM domain for the USB super-speed logic. > > Currently to make the drivers work, either the related PM domains needs to stay > powered on always or the PM domain topology needs to be in-correctly modelled > through sub-domains. In both cases PM domains may be powered on while they > don't need to be, so in the end this means - wasting power -. > > As stated above, this series intends to address these problem from a PM > infrastructure point of view. More details are available in each changelog. > > It should be noted that this series has been tested on HW, however only by using > a home-cooked test PM domain driver for genpd and together with a test driver. > This allowed me to play with PM domain (genpd), runtime PM and device links. > > Any further deployment for real use cases are greatly appreciated. I am happy to > to help, if needed! Reviewed-by: Viresh Kumar -- viresh