From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1034631AbcIWO1q (ORCPT ); Fri, 23 Sep 2016 10:27:46 -0400 Received: from mail-io0-f194.google.com ([209.85.223.194]:34292 "EHLO mail-io0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965608AbcIWO1n (ORCPT ); Fri, 23 Sep 2016 10:27:43 -0400 MIME-Version: 1.0 In-Reply-To: <1c217cf4-8682-8e6d-6958-419923e995cd@nvidia.com> References: <1474367287-10402-1-git-send-email-jonathanh@nvidia.com> <1474367287-10402-3-git-send-email-jonathanh@nvidia.com> <658004af-e4f4-8b0c-cdc1-43661d331d70@nvidia.com> <1c217cf4-8682-8e6d-6958-419923e995cd@nvidia.com> From: Geert Uytterhoeven Date: Fri, 23 Sep 2016 16:27:41 +0200 X-Google-Sender-Auth: 4aglenDP3MGhjTMD7HguGDWGkf4 Message-ID: Subject: Re: [RFC PATCH 2/3] PM / Domains: Add support for devices with multiple domains To: Jon Hunter Cc: "Rafael J. Wysocki" , Kevin Hilman , Ulf Hansson , Linux PM list , "linux-kernel@vger.kernel.org" , linux-tegra@vger.kernel.org, Linux-Renesas Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Jon, On Fri, Sep 23, 2016 at 2:57 PM, Jon Hunter wrote: > On 21/09/16 15:57, Geert Uytterhoeven wrote: >> On Wed, Sep 21, 2016 at 4:37 PM, Jon Hunter wrote: >>> On 21/09/16 09:53, Geert Uytterhoeven wrote: >>>> On Tue, Sep 20, 2016 at 12:28 PM, Jon Hunter wrote: >>>>> Some devices may require more than one PM domain to operate and this is >>>>> not currently by the PM domain framework. Furthermore, the current Linux >>>>> 'device' structure only allows devices to be associated with a single PM >>>>> domain and so cannot easily be associated with more than one. To allow >>>>> devices to be associated with more than one PM domain, if multiple >>>>> domains are defined for a given device (eg. via device-tree), then: >>>>> 1. Create a new PM domain for this device. The name of the new PM domain >>>>> created matches the device name for which it was created for. >>>>> 2. Register the new PM domain as a sub-domain for all PM domains >>>>> required by the device. >>>>> 3. Attach the device to the new PM domain. >>>> >>>> This looks a suboptimal to me: if you have n devices sharing the same PM >>>> domains, you would add n new subdomains? >>> >>> BTW, would this be the case today for some renesas devices or are you >>> just pointing this out as something that could be optimised/improved? >> >> This is the case for all Renesas SoCs that have power areas: devices belong >> to both the PM domain for the power area, and to the PM domain for the clock >> domain. > > To quantify this a bit, for the Renesas case, how many of these > duplicated domains would there be if you were to use this approach as-is? for i in $(git grep -l renesas, -- "*dts*") ; do echo --- $i ---; git grep -w power-domains $i | sort | uniq -c | sort -n;done tells you how many (supported) devices are (currently) present in each PM domain. Most of these (all but devices in CPU/SCU power areas) are also part of a clock domain. The synthetic R8A779*_PD_ALWAYS_ON domains could be dropped again, as we could just refer to the CPG/MSSR node for the clock domain instead. For older SH/R-Mobile SoCs with lots of hierarchical domains, that gives us, after removing the above: 1 arch/arm/boot/dts/r8a7740.dtsi: power-domains = <&pd_a4mp>; 1 arch/arm/boot/dts/r8a7740.dtsi: power-domains = <&pd_d4>; 2 arch/arm/boot/dts/r8a7740.dtsi: power-domains = <&pd_c5>; 3 arch/arm/boot/dts/r8a7740.dtsi: power-domains = <&pd_a4r>; 6 arch/arm/boot/dts/r8a7740.dtsi: power-domains = <&pd_a4s>; 15 arch/arm/boot/dts/r8a7740.dtsi: power-domains = <&pd_a3sp>; R-Car Gen1/Gen2 have all devices in the "always on" PM domain, so they're not affected. R-Car Gen3 again has devices in power areas, mostly for graphics related purposes: 16 arch/arm64/boot/dts/renesas/r8a7795.dtsi: power-domains = <&sysc R8A7795_PD_A3VP>; Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds