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 X-Spam-Level: X-Spam-Status: No, score=-2.4 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id DA355C33C99 for ; Fri, 10 Jan 2020 06:54:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A6BB620673 for ; Fri, 10 Jan 2020 06:54:25 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=linaro.org header.i=@linaro.org header.b="sKUMJWsX" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731547AbgAJGyZ (ORCPT ); Fri, 10 Jan 2020 01:54:25 -0500 Received: from mail-pg1-f193.google.com ([209.85.215.193]:45144 "EHLO mail-pg1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731455AbgAJGyY (ORCPT ); Fri, 10 Jan 2020 01:54:24 -0500 Received: by mail-pg1-f193.google.com with SMTP id b9so523808pgk.12 for ; Thu, 09 Jan 2020 22:54:24 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=YhPLZOvbusu+BDcW4xtLEV0ezjrgdDBJUzmow7dtjMQ=; b=sKUMJWsXvcFP9jEO0Hl4uUyNvbyljQCLxhGsldiqDRvsC8IpLpEay5tiVJTep7pkQo oRqBgROQLiR2Dvoq/TyO1UMoQhdyRJ3wjy/MPdywSKlfQfgIT8OA5zHb8eDxN8hur6+m bmj0RfiXa6xUTOzhi3oi6cDzqHFZQqMWYm1TGCbkHjBAjoW1ygXyRXpF3uzJoPIuknpy U45mfuGgCk9q6RAjFHyZZE2ggGK2YJciePz/phNcN5zwDp79efcs1taM0Ee8bj8mvq6Z Vmx+d9BNX8QdTcgXvWiC6oEoF3c/fN21NQ2PM/PN7y0A+ZT+UCIE+AziDVobHNKrEQ5H 6cpQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=YhPLZOvbusu+BDcW4xtLEV0ezjrgdDBJUzmow7dtjMQ=; b=PyN1JoBMNVdY+/YGeW6q85lpQLCqz7d8MVziNAH0WSo3IfjwhNU+lfWW/aOeTju88D O/U3TIIKWFGFDzpMfQ4Q2MXLTWVcPQQFd982zzgxy9ac20VGkK6i/xhVDv05oac8Ejzr OlFAHmd4TYw2izhHyh3Z3Zk6Y9aojfPefP69t6hFSQTaWPyu4sP2PQV0r0/qcRnUS4yl HNwmehCJC+1H36xsuzfUW4QJhCtTgpNPsDGrzg6S688iS9iWCUDVA3LbLUvWmwmxH7a6 9wFZsME3aDXp8D2zOWSaHa75+245W+xPx2ZVmUzrUKl1KygpPD54OzuZQVE16qjYPIOY 10Hw== X-Gm-Message-State: APjAAAV0pW20oMDp8u6OP7YuJfP7SYEqhRxYvGn3RP2TKN9yGwNYWIz1 5ld3r8YEyT9WNDc/1oliEp/cuA== X-Google-Smtp-Source: APXvYqyqmwrNqG8WUg323dOQJc2jziGsBSe/4bAS5Q+Tv3gJE3iTY9fjXWBEohxRSFWlHgkV0K65JA== X-Received: by 2002:a63:4824:: with SMTP id v36mr2501774pga.343.1578639263873; Thu, 09 Jan 2020 22:54:23 -0800 (PST) Received: from localhost ([122.172.140.51]) by smtp.gmail.com with ESMTPSA id i3sm1384035pfo.72.2020.01.09.22.54.22 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 09 Jan 2020 22:54:23 -0800 (PST) Date: Fri, 10 Jan 2020 12:24:20 +0530 From: Viresh Kumar To: Saravana Kannan Cc: Rob Herring , Mark Rutland , Viresh Kumar , Nishanth Menon , Stephen Boyd , "Rafael J. Wysocki" , Georgi Djakov , Vincent Guittot , "Sweeney, Sean" , David Dai , adharmap@codeaurora.org, Rajendra Nayak , Sibi Sankar , Bjorn Andersson , Evan Green , Android Kernel Team , Linux PM , "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" , LKML Subject: Re: [PATCH v6 2/3] OPP: Add support for bandwidth OPP tables Message-ID: <20200110065420.3bp4fjj2wbezoyrc@vireshk-i7> References: <20191207002424.201796-1-saravanak@google.com> <20191207002424.201796-3-saravanak@google.com> <20200108105348.p4y3s2mbuchiu4mf@vireshk-i7> <20200109043108.fzvk3hp7vodtw6zy@vireshk-i7> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20180716-391-311a52 Sender: devicetree-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org On 09-01-20, 10:35, Saravana Kannan wrote: > Agreed for the example you are giving where PM domains/voltages are > dropped automatically when dropping the device freq to suspend freq. > I'm just wondering about a different scenario where if some power > domain needed to be at say 0.5v when it's suspended (no consumer using > it) The domain should be powered off in this case I think. > to not lose state, or to come back up without brownouts, etc then > suspend OPP for PM domains might be useful. But I don't know enough > about that to speak with authority, so I'll leave it at this. > > I see this suspend-opp as a way to mark to what level the bandwidth > needs to be dropped to/brought back up from during suspend/resume by > the driver making interconnect bandwidth requests. For example, what > if the CPU -> DDR needed to be at some level to avoid suspend/resume > issues (say CPU bug with respect to timing/latencies)? In this > example, the CPU driver would be the one making bandwidth requests for > CPU -> DDR bandwidth during normal operation and during > suspend/resume. So it's basically exactly the same way it would treat > CPU freq OPP. I understand your concerns but to me it all looks hypothetical right now. I am not saying we won't support suspend-opp for interconnect or domains, but that we should do it only if it is required. > Btw, I don't have a strong opinion on this. But, even if we do only a > rate comparison, what does it even mean to compare rates for genpd or > BW opp tables? We will never do the comparison because those tables will never have the suspend OPP in the respective tables. -- viresh