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=-1.0 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, URIBL_BLOCKED autolearn=ham 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 B29E1C04EB8 for ; Mon, 10 Dec 2018 14:50:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 600B720851 for ; Mon, 10 Dec 2018 14:50:23 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=linaro.org header.i=@linaro.org header.b="dGOgURgK" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 600B720851 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linaro.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727757AbeLJOuW (ORCPT ); Mon, 10 Dec 2018 09:50:22 -0500 Received: from mail-wm1-f68.google.com ([209.85.128.68]:37147 "EHLO mail-wm1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727516AbeLJOuV (ORCPT ); Mon, 10 Dec 2018 09:50:21 -0500 Received: by mail-wm1-f68.google.com with SMTP id g67so11491084wmd.2 for ; Mon, 10 Dec 2018 06:50:18 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=subject:to:cc:references:from:openpgp:autocrypt:message-id:date :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=hYoCWHxzgcNgM9m158Tlhp08Xhh3hSfnPCS9vWo0XQk=; b=dGOgURgKk9ECSKcZ6hTzEYSeuXCkgsLvF2OcxUYmqam13lMmm8HwAMToIVU20gNjZK WL8G3kt3364YAQzI4H35zZhSCzVQy4xxLqeeHqcRuRY9To4NFyu1z4V31ZryqpSNp3WM zFN52u96tj73ymTKQOm5mmtnuPffauYbfO8nA= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:openpgp:autocrypt :message-id:date:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=hYoCWHxzgcNgM9m158Tlhp08Xhh3hSfnPCS9vWo0XQk=; b=eoXiKwHxbTFbLyHCB+kyhm9XKUt2CktVXEeM/TDYbLiOKCdKBq338EKsyATSoSNvin xrFIe85wg9YzP9mL0FgBSRzp+xq7CGJLmcnipzHLU0Bfmmc5g4kW7jkz8FGVLHY7zWfj P8a8Sl/iX7mmRKzHro6XUGN5lM99e7QaBLVNpQu7FYWTTbOuP6MJowEMi3SVfviwXLMc DAkhQxfQbSAhp4qJPKCdEShrrnP6um4rMepH/Y8A1Mz1ZLkEeLlHka5XcJ18D6otWJee qiSmxF/Ti3MwHUvq7hTeeV83eKDkqq9FoeChXYW1Izx8wXjHTpXXWgn2gtkEWHqgI6E2 RbYg== X-Gm-Message-State: AA+aEWZg+Q9zYed+ck5yBf1SEQJTkomkOMFKu0OR9FQviijUS4PbeY2+ /nmDRB3fR3harNbignJwpr/wzw== X-Google-Smtp-Source: AFSGD/WgTYGBsbYadFTWtdFZnA3+qDKfkbUzyG+xDWK/B3TLYgWmtHl3tEOr4napROpRpG0ZCrfFFw== X-Received: by 2002:a7b:c095:: with SMTP id r21mr11147070wmh.118.1544453417221; Mon, 10 Dec 2018 06:50:17 -0800 (PST) Received: from [10.44.66.8] ([212.45.67.2]) by smtp.googlemail.com with ESMTPSA id s16sm13865503wrt.77.2018.12.10.06.50.02 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 10 Dec 2018 06:50:16 -0800 (PST) Subject: Re: [PATCH v10 0/8] Introduce on-chip interconnect API To: "Rafael J. Wysocki" , Greg Kroah-Hartman , Arnd Bergmann , Olof Johansson Cc: evgreen@chromium.org, Linux PM , "Rafael J. Wysocki" , Rob Herring , Michael Turquette , Kevin Hilman , Vincent Guittot , Saravana Kannan , bjorn.andersson@linaro.org, Amit Kucheria , seansw@qti.qualcomm.com, daidavid1@codeaurora.org, Mark Rutland , Lorenzo Pieralisi , abailon@baylibre.com, maxime.ripard@bootlin.com, Thierry Reding , ksitaraman@nvidia.com, sanjayc@nvidia.com, "devicetree@vger.kernel.org" , Linux Kernel Mailing List , Linux ARM , linux-arm-msm , linux-tegra@vger.kernel.org, Doug Anderson , Andy Gross References: <20181127180349.29997-1-georgi.djakov@linaro.org> <20181206145547.GA7884@kroah.com> <6923d6ed-e357-b083-1830-8396d788efe5@linaro.org> From: Georgi Djakov Openpgp: preference=signencrypt Autocrypt: addr=georgi.djakov@linaro.org; prefer-encrypt=mutual; keydata= xsFNBFjTuRcBEACyAOVzghvyN19Sa/Nit4LPBWkICi5W20p6bwiZvdjhtuh50H5q4ktyxJtp 1+s8dMSa/j58hAWhrc2SNL3fttOCo+MM1bQWwe8uMBQJP4swgXf5ZUYkSssQlXxGKqBSbWLB uFHOOBTzaQBaNgsdXo+mQ1h8UCgM0zQOmbs2ort8aHnH2i65oLs5/Xgv/Qivde/FcFtvEFaL 0TZ7odM67u+M32VetH5nBVPESmnEDjRBPw/DOPhFBPXtal53ZFiiRr6Bm1qKVu3dOEYXHHDt nF13gB+vBZ6x5pjl02NUEucSHQiuCc2Aaavo6xnuBc3lnd4z/xk6GLBqFP3P/eJ56eJv4d0B 0LLgQ7c1T3fU4/5NDRRCnyk6HJ5+HSxD4KVuluj0jnXW4CKzFkKaTxOp7jE6ZD/9Sh74DM8v etN8uwDjtYsM07I3Szlh/I+iThxe/4zVtUQsvgXjwuoOOBWWc4m4KKg+W4zm8bSCqrd1DUgL f67WiEZgvN7tPXEzi84zT1PiUOM98dOnmREIamSpKOKFereIrKX2IcnZn8jyycE12zMkk+Sc ASMfXhfywB0tXRNmzsywdxQFcJ6jblPNxscnGMh2VlY2rezmqJdcK4G4Lprkc0jOHotV/6oJ mj9h95Ouvbq5TDHx+ERn8uytPygDBR67kNHs18LkvrEex/Z1cQARAQABzShHZW9yZ2kgRGph a292IDxnZW9yZ2kuZGpha292QGxpbmFyby5vcmc+wsF+BBMBAgAoBQJY07kXAhsDBQkHhM4A BgsJCAcDAgYVCAIJCgsEFgIDAQIeAQIXgAAKCRCyi/eZcnWWUuvsD/4miikUeAO6fU2Xy3fT l7RUCeb2Uuh1/nxYoE1vtXcow6SyAvIVTD32kHXucJJfYy2zFzptWpvD6Sa0Sc58qe4iLY4j M54ugOYK7XeRKkQHFqqR2T3g/toVG1BOLS2atooXEU+8OFbpLkBXbIdItqJ1M1SEw8YgKmmr JlLAaKMq3hMb5bDQx9erq7PqEKOB/Va0nNu17IL58q+Q5Om7S1x54Oj6LiG/9kNOxQTklOQZ t61oW1Ewjbl325fW0/Lk0QzmfLCrmGXXiedFEMRLCJbVImXVKdIt/Ubk6SAAUrA5dFVNBzm2 L8r+HxJcfDeEpdOZJzuwRyFnH96u1Xz+7X2V26zMU6Wl2+lhvr2Tj7spxjppR+nuFiybQq7k MIwyEF0mb75RLhW33sdGStCZ/nBsXIGAUS7OBj+a5fm47vQKv6ekg60oRTHWysFSJm1mlRyq exhI6GwUo5GM/vE36rIPSJFRRgkt6nynoba/1c4VXxfhok2rkP0x3CApJ5RimbvITTnINY0o CU6f1ng1I0A1UTi2YcLjFq/gmCdOHExT4huywfu1DDf0p1xDyPA1FJaii/gJ32bBP3zK53hM dj5S7miqN7F6ZpvGSGXgahQzkGyYpBR5pda0m0k8drV2IQn+0W8Qwh4XZ6/YdfI81+xyFlXc CJjljqsMCJW6PdgEH87BTQRY07kXARAAvupGd4Jdd8zRRiF+jMpv6ZGz8L55Di1fl1YRth6m lIxYTLwGf0/p0oDLIRldKswena3fbWh5bbTMkJmRiOQ/hffhPSNSyyh+WQeLY2kzl6geiHxD zbw37e2hd3rWAEfVFEXOLnmenaUeJFyhA3Wd8OLdRMuoV+RaLhNfeHctiEn1YGy2gLCq4VNb 4Wj5hEzABGO7+LZ14hdw3hJIEGKtQC65Jh/vTayGD+qdwedhINnIqslk9tCQ33a+jPrCjXLW X29rcgqigzsLHH7iVHWA9R5Aq7pCy5hSFsl4NBn1uV6UHlyOBUuiHBDVwTIAUnZ4S8EQiwgv WQxEkXEWLM850V+G6R593yZndTr3yydPgYv0xEDACd6GcNLR/x8mawmHKzNmnRJoOh6Rkfw2 fSiVGesGo83+iYq0NZASrXHAjWgtZXO1YwjW9gCQ2jYu9RGuQM8zIPY1VDpQ6wJtjO/KaOLm NehSR2R6tgBJK7XD9it79LdbPKDKoFSqxaAvXwWgXBj0Oz+Y0BqfClnAbxx3kYlSwfPHDFYc R/ppSgnbR5j0Rjz/N6Lua3S42MDhQGoTlVkgAi1btbdV3qpFE6jglJsJUDlqnEnwf03EgjdJ 6KEh0z57lyVcy5F/EUKfTAMZweBnkPo+BF2LBYn3Qd+CS6haZAWaG7vzVJu4W/mPQzsAEQEA AcLBZQQYAQIADwUCWNO5FwIbDAUJB4TOAAAKCRCyi/eZcnWWUhlHD/0VE/2x6lKh2FGP+QHH UTKmiiwtMurYKJsSJlQx0T+j/1f+zYkY3MDX+gXa0d0xb4eFv8WNlEjkcpSPFr+pQ7CiAI33 99kAVMQEip/MwoTYvM9NXSMTpyRJ/asnLeqa0WU6l6Z9mQ41lLzPFBAJ21/ddT4xeBDv0dxM GqaH2C6bSnJkhSfSja9OxBe+F6LIAZgCFzlogbmSWmUdLBg+sh3K6aiBDAdZPUMvGHzHK3fj gHK4GqGCFK76bFrHQYgiBOrcR4GDklj4Gk9osIfdXIAkBvRGw8zg1zzUYwMYk+A6v40gBn00 OOB13qJe9zyKpReWMAhg7BYPBKIm/qSr82aIQc4+FlDX2Ot6T/4tGUDr9MAHaBKFtVyIqXBO xOf0vQEokkUGRKWBE0uA3zFVRfLiT6NUjDQ0vdphTnsdA7h01MliZLQ2lLL2Mt5lsqU+6sup Tfql1omgEpjnFsPsyFebzcKGbdEr6vySGa3Cof+miX06hQXKe99a5+eHNhtZJcMAIO89wZmj 7ayYJIXFqjl/X0KBcCbiAl4vbdBw1bqFnO4zd1lMXKVoa29UHqby4MPbQhjWNVv9kqp8A39+ E9xw890l1xdERkjVKX6IEJu2hf7X3MMl9tOjBK6MvdOUxvh1bNNmXh7OlBL1MpJYY/ydIm3B KEmKjLDvB0pePJkdTw== Message-ID: <9a3aae02-c7e0-97e3-2330-af4fccee6c14@linaro.org> Date: Mon, 10 Dec 2018 16:50:00 +0200 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/10/18 13:00, Rafael J. Wysocki wrote: > On Mon, Dec 10, 2018 at 11:18 AM Georgi Djakov wrote: >> >> Hi Rafael, >> >> On 12/10/18 11:04, Rafael J. Wysocki wrote: >>> On Thu, Dec 6, 2018 at 3:55 PM Greg KH wrote: >>>> >>>> On Wed, Dec 05, 2018 at 12:41:35PM -0800, Evan Green wrote: >>>>> On Tue, Nov 27, 2018 at 10:03 AM Georgi Djakov wrote: >>>>>> >>>>>> Modern SoCs have multiple processors and various dedicated cores (video, gpu, >>>>>> graphics, modem). These cores are talking to each other and can generate a >>>>>> lot of data flowing through the on-chip interconnects. These interconnect >>>>>> buses could form different topologies such as crossbar, point to point buses, >>>>>> hierarchical buses or use the network-on-chip concept. >>>>>> >>>>>> These buses have been sized usually to handle use cases with high data >>>>>> throughput but it is not necessary all the time and consume a lot of power. >>>>>> Furthermore, the priority between masters can vary depending on the running >>>>>> use case like video playback or CPU intensive tasks. >>>>>> >>>>>> Having an API to control the requirement of the system in terms of bandwidth >>>>>> and QoS, so we can adapt the interconnect configuration to match those by >>>>>> scaling the frequencies, setting link priority and tuning QoS parameters. >>>>>> This configuration can be a static, one-time operation done at boot for some >>>>>> platforms or a dynamic set of operations that happen at run-time. >>>>>> >>>>>> This patchset introduce a new API to get the requirement and configure the >>>>>> interconnect buses across the entire chipset to fit with the current demand. >>>>>> The API is NOT for changing the performance of the endpoint devices, but only >>>>>> the interconnect path in between them. >>>>> >>>>> For what it's worth, we are ready to land this in Chrome OS. I think >>>>> this series has been very well discussed and reviewed, hasn't changed >>>>> much in the last few spins, and is in good enough shape to use as a >>>>> base for future patches. Georgi's also done a great job reaching out >>>>> to other SoC vendors, and there appears to be enough consensus that >>>>> this framework will be usable by more than just Qualcomm. There are >>>>> also several drivers out on the list trying to add patches to use this >>>>> framework, with more to come, so it made sense (to us) to get this >>>>> base framework nailed down. In my experiments this is an important >>>>> piece of the overall power management story, especially on systems >>>>> that are mostly idle. >>>>> >>>>> I'll continue to track changes to this series and we will ultimately >>>>> reconcile with whatever happens upstream, but I thought it was worth >>>>> sending this note to express our "thumbs up" towards this framework. >>>> >>>> Looks like a v11 will be forthcoming, so I'll wait for that one to apply >>>> it to the tree if all looks good. >>> >>> I'm honestly not sure if it is ready yet. >>> >>> New versions are coming on and on, which may make such an impression, >>> but we had some discussion on it at the LPC and some serious questions >>> were asked during it, for instance regarding the DT binding introduced >>> here. I'm not sure how this particular issue has been addressed here, >>> for example. >> >> There have been no changes in bindings since v4 (other than squashing >> consumer and provider bindings into a single patch and fixing typos). >> >> The last DT comment was on v9 [1] where Rob wanted confirmation from >> other SoC vendors that this works for them too. And now we have that >> confirmation and there are patches posted on the list [2]. > > OK > >> The second thing (also discussed at LPC) was about possible cases where >> some consumer drivers can't calculate how much bandwidth they actually >> need and how to address that. The proposal was to extend the OPP >> bindings with one more property, but this is not part of this patchset. >> It is a future step that needs more discussion on the mailing list. If a >> driver really needs some bandwidth data now, it should be put into the >> driver and not in DT. After we have enough consumers, we can discuss >> again if it makes sense to extract something into DT or not. > > That's fine by me. > > Admittedly, I have some reservations regarding the extent to which > this approach will turn out to be useful in practice, but I guess as > long as there is enough traction, the best way to find out it to try > and see. :-) > > From now on I will assume that this series is going to be applied by Greg. That was the initial idea, but the problem is that there is a recent change in the cmd_db API (needed by the sdm845 provider driver), which is going through arm-soc/qcom/drivers. So either Greg pulls also the qcom-drivers-for-4.21 tag from Andy or the whole series goes via Olof and Arnd. Maybe there are other options. I don't have any preference and don't want to put extra burden on any maintainers, so i am ok with what they prefer. Thanks, Georgi