From mboxrd@z Thu Jan 1 00:00:00 1970 From: Greg Kroah-Hartman Subject: Re: [PATCH v10 0/8] Introduce on-chip interconnect API Date: Thu, 10 Jan 2019 17:29:06 +0100 Message-ID: <20190110162906.GA19693@kroah.com> References: <20181127180349.29997-1-georgi.djakov@linaro.org> <20181206145547.GA7884@kroah.com> <6923d6ed-e357-b083-1830-8396d788efe5@linaro.org> <9a3aae02-c7e0-97e3-2330-af4fccee6c14@linaro.org> <20181211065808.GB5161@kroah.com> <199be960-032a-d72d-4293-820e23a15b7a@linaro.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: Georgi Djakov Cc: "Rafael J. Wysocki" , Arnd Bergmann , Olof Johansson , 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 List-Id: linux-arm-msm@vger.kernel.org On Thu, Jan 10, 2019 at 04:19:14PM +0200, Georgi Djakov wrote: > Hi Greg, > > On 12/17/18 13:17, Georgi Djakov wrote: > > Hi Greg, > > > > On 12/11/18 08:58, Greg Kroah-Hartman wrote: > >> On Mon, Dec 10, 2018 at 04:50:00PM +0200, Georgi Djakov wrote: > >>> 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. > >> > >> Let me take the time later this week to review the code, which I haven't > >> done in a while... > >> > > > > When you get a chance to review, please keep in mind that the latest > > version is v12 (from 08.Dec). The same is also available in linux-next > > with no reported issues. > > The dependencies for this patchset have been already merged in v5.0-rc1, > so i was wondering if this can still go into -rc2? Various patches that > use this API are already posted and having it sooner will make dealing > with dependencies and merge paths a bit easier during the next merge > window. Or i can just rebase and resend everything targeting v5.1. We can't add new features after -rc1, sorry. Please rebase and resend to target 5.1 thanks, greg k-h 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=-7.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, URIBL_BLOCKED,USER_AGENT_MUTT autolearn=unavailable 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 AE79FC43387 for ; Thu, 10 Jan 2019 17:10:57 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 797F520685 for ; Thu, 10 Jan 2019 17:10:57 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="RTFUtU4C"; 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h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=RKQoQkDIkr7iCduLvMEM+BbU7RcbKqDVkHd49EigLMqa3ClUI311xHt9bz4nr1aNd T6qdY8RonJLVOvNLmwBrWvBjGjLS5+zfB6LOhTRg68++BV7Kia3iGW4QErjfDRmQop 7UxlselKsN3r3ooc+WAWBKn4mtXFw87EYU+/7fN0= Date: Thu, 10 Jan 2019 17:29:06 +0100 From: Greg Kroah-Hartman To: Georgi Djakov Subject: Re: [PATCH v10 0/8] Introduce on-chip interconnect API Message-ID: <20190110162906.GA19693@kroah.com> References: <20181127180349.29997-1-georgi.djakov@linaro.org> <20181206145547.GA7884@kroah.com> <6923d6ed-e357-b083-1830-8396d788efe5@linaro.org> <9a3aae02-c7e0-97e3-2330-af4fccee6c14@linaro.org> <20181211065808.GB5161@kroah.com> <199be960-032a-d72d-4293-820e23a15b7a@linaro.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.11.2 (2019-01-07) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190110_112911_995498_79614F00 X-CRM114-Status: GOOD ( 49.16 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , Doug Anderson , sanjayc@nvidia.com, "Rafael J. Wysocki" , maxime.ripard@bootlin.com, Michael Turquette , daidavid1@codeaurora.org, bjorn.andersson@linaro.org, Saravana Kannan , abailon@baylibre.com, Lorenzo Pieralisi , Vincent Guittot , seansw@qti.qualcomm.com, Kevin Hilman , evgreen@chromium.org, ksitaraman@nvidia.com, "devicetree@vger.kernel.org" , Arnd Bergmann , Linux PM , linux-arm-msm , Andy Gross , Rob Herring , linux-tegra@vger.kernel.org, Linux ARM , "Rafael J. Wysocki" , Linux Kernel Mailing List , Amit Kucheria , Thierry Reding , Olof Johansson Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu, Jan 10, 2019 at 04:19:14PM +0200, Georgi Djakov wrote: > Hi Greg, > > On 12/17/18 13:17, Georgi Djakov wrote: > > Hi Greg, > > > > On 12/11/18 08:58, Greg Kroah-Hartman wrote: > >> On Mon, Dec 10, 2018 at 04:50:00PM +0200, Georgi Djakov wrote: > >>> 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. > >> > >> Let me take the time later this week to review the code, which I haven't > >> done in a while... > >> > > > > When you get a chance to review, please keep in mind that the latest > > version is v12 (from 08.Dec). The same is also available in linux-next > > with no reported issues. > > The dependencies for this patchset have been already merged in v5.0-rc1, > so i was wondering if this can still go into -rc2? Various patches that > use this API are already posted and having it sooner will make dealing > with dependencies and merge paths a bit easier during the next merge > window. Or i can just rebase and resend everything targeting v5.1. We can't add new features after -rc1, sorry. Please rebase and resend to target 5.1 thanks, greg k-h _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel 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=-7.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, URIBL_BLOCKED,USER_AGENT_MUTT 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 B5F9AC43387 for ; Thu, 10 Jan 2019 16:29:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7CB5F2173B for ; Thu, 10 Jan 2019 16:29:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1547137752; bh=0TNDLtP5cTQhN0wkLzWrHUEFAuWPdSuNN1R+VjRe4Rk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=BC/krUe2OaKNNb4I15jreIHEPFWZFX00am4mL3j5VbWYbVijCImjuRdHIG0HEtXR4 hV9RsJeVAvIAXFAWwz9OSUGOr16NKGX8042pwnAwa+7uUj4C69P16MNMCklzlM9jEN fiJXdhuerACu3oyvzs8XE5m1drAFyTGltsWcWH68= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727862AbfAJQ3L (ORCPT ); Thu, 10 Jan 2019 11:29:11 -0500 Received: from mail.kernel.org ([198.145.29.99]:37742 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726560AbfAJQ3K (ORCPT ); Thu, 10 Jan 2019 11:29:10 -0500 Received: from localhost (5356596B.cm-6-7b.dynamic.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id C6B6A206B7; Thu, 10 Jan 2019 16:29:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1547137749; bh=0TNDLtP5cTQhN0wkLzWrHUEFAuWPdSuNN1R+VjRe4Rk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=RKQoQkDIkr7iCduLvMEM+BbU7RcbKqDVkHd49EigLMqa3ClUI311xHt9bz4nr1aNd T6qdY8RonJLVOvNLmwBrWvBjGjLS5+zfB6LOhTRg68++BV7Kia3iGW4QErjfDRmQop 7UxlselKsN3r3ooc+WAWBKn4mtXFw87EYU+/7fN0= Date: Thu, 10 Jan 2019 17:29:06 +0100 From: Greg Kroah-Hartman To: Georgi Djakov Cc: "Rafael J. Wysocki" , Arnd Bergmann , Olof Johansson , 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 Subject: Re: [PATCH v10 0/8] Introduce on-chip interconnect API Message-ID: <20190110162906.GA19693@kroah.com> References: <20181127180349.29997-1-georgi.djakov@linaro.org> <20181206145547.GA7884@kroah.com> <6923d6ed-e357-b083-1830-8396d788efe5@linaro.org> <9a3aae02-c7e0-97e3-2330-af4fccee6c14@linaro.org> <20181211065808.GB5161@kroah.com> <199be960-032a-d72d-4293-820e23a15b7a@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.11.2 (2019-01-07) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jan 10, 2019 at 04:19:14PM +0200, Georgi Djakov wrote: > Hi Greg, > > On 12/17/18 13:17, Georgi Djakov wrote: > > Hi Greg, > > > > On 12/11/18 08:58, Greg Kroah-Hartman wrote: > >> On Mon, Dec 10, 2018 at 04:50:00PM +0200, Georgi Djakov wrote: > >>> 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. > >> > >> Let me take the time later this week to review the code, which I haven't > >> done in a while... > >> > > > > When you get a chance to review, please keep in mind that the latest > > version is v12 (from 08.Dec). The same is also available in linux-next > > with no reported issues. > > The dependencies for this patchset have been already merged in v5.0-rc1, > so i was wondering if this can still go into -rc2? Various patches that > use this API are already posted and having it sooner will make dealing > with dependencies and merge paths a bit easier during the next merge > window. Or i can just rebase and resend everything targeting v5.1. We can't add new features after -rc1, sorry. Please rebase and resend to target 5.1 thanks, greg k-h