From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8130EC433EF for ; Thu, 21 Oct 2021 13:33:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 69E4761130 for ; Thu, 21 Oct 2021 13:33:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229878AbhJUNfk (ORCPT ); Thu, 21 Oct 2021 09:35:40 -0400 Received: from foss.arm.com ([217.140.110.172]:42714 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230361AbhJUNfi (ORCPT ); Thu, 21 Oct 2021 09:35:38 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 76259ED1; Thu, 21 Oct 2021 06:33:22 -0700 (PDT) Received: from bogus (unknown [10.57.25.56]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id DDBF93F73D; Thu, 21 Oct 2021 06:33:20 -0700 (PDT) Date: Thu, 21 Oct 2021 14:33:18 +0100 From: Sudeep Holla To: Ulf Hansson Cc: Rob Herring , Viresh Kumar , Linux Kernel Mailing List , DTML , Sudeep Holla , Manivannan Sadhasivam , Hector Yuan , Bjorn Andersson Subject: Re: [PATCH v4] dt-bindings: dvfs: Add support for generic performance domains Message-ID: <20211021133318.74f4tdwpishicefb@bogus> References: <20210517155458.1016707-1-sudeep.holla@arm.com> <20211014145555.uoi2hyoonrptrd5m@bogus> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Oct 21, 2021 at 03:13:30PM +0200, Ulf Hansson wrote: > On Wed, 20 Oct 2021 at 14:11, Rob Herring wrote: > > [...] > > 'power domains' in DT is supposed to mean physical power islands in > > the h/w where as genpd can be whatever you want. Are power and > > performance domains always 1:1? > > I wouldn't say that "power domains" *must* correspond to physical > power islands. At least, that's not the way the bindings are being > used. For example, if it makes better sense to keep some of the logic > in FW, rather than describing a complete topology in DT, that should > be perfectly fine. > I agree. The DT must either have h/w view or f/w view of the topology and not both(that is inviting more trouble in terms of bindings as well as handling it in the OSPM). > Additionally, I am not suggesting that "performance domains" and > "power domains" must map 1:1. A device can be performance managed > through one domain and power managed by another, that would be > perfectly fine to me. I don't understand what you mean by that. Do you expect to create a genpd with no power domain ops and just performance ops to deal with scenario I have been presenting(i.e. power domains for a set of devices(CPUs in particular) aren't exposed to OSPM while performance domains are). I really don't like to create psuedo/dummy power domains with no useful info(as f/w hides or abstracts it) just to represent the performance domains. Also with CPUs you can imagine all sort of combinations like: 1. cluster level perf domain + cpu level power domains 3. cluster level perf domain + cluster level power domains 2. cpu level perf domain + cpu level power domains 4. cpu level perf domain + cluster level power domains + power domains not available to OSPM in all the 4 combo. So I am really struggling to visualise a way to represent these based on your suggestion. -- Regards, Sudeep