From: Ulf Hansson <ulf.hansson@linaro.org>
To: Hector Martin <marcan@marcan.st>
Cc: Viresh Kumar <viresh.kumar@linaro.org>,
Sibi Sankar <sibis@codeaurora.org>,
Saravana Kannan <saravanak@google.com>,
Linux ARM <linux-arm-kernel@lists.infradead.org>,
Alyssa Rosenzweig <alyssa@rosenzweig.io>,
Sven Peter <sven@svenpeter.dev>, Marc Zyngier <maz@kernel.org>,
Mark Kettenis <mark.kettenis@xs4all.nl>,
Michael Turquette <mturquette@baylibre.com>,
Stephen Boyd <sboyd@kernel.org>, Rob Herring <robh+dt@kernel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>,
Viresh Kumar <vireshk@kernel.org>, Nishanth Menon <nm@ti.com>,
Catalin Marinas <catalin.marinas@arm.com>,
"Rafael J. Wysocki" <rafael@kernel.org>,
Kevin Hilman <khilman@kernel.org>,
linux-clk <linux-clk@vger.kernel.org>,
DTML <devicetree@vger.kernel.org>,
Linux PM <linux-pm@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [RFC PATCH 4/9] opp: core: Don't warn if required OPP device does not exist
Date: Thu, 14 Oct 2021 14:55:30 +0200 [thread overview]
Message-ID: <CAPDyKFrFX93XV8a7e7oo1N5weWp2auq=_94fTnzr2EkO3c37Ug@mail.gmail.com> (raw)
In-Reply-To: <bd07f4b3-6ebf-e074-c1cd-0ef501e8324f@marcan.st>
On Thu, 14 Oct 2021 at 13:43, Hector Martin <marcan@marcan.st> wrote:
>
> On 14/10/2021 18.55, Ulf Hansson wrote:
> > Yes, this sounds like you should move away from modeling the memory
> > part as a parent genpd for the CPUs' genpd.
> >
> > As Viresh pointed out, a devfreq driver seems like a better way to do
> > this. As a matter of fact, there are already devfreq drivers that do
> > this, unless I am mistaken.
> >
> > It looks like devfreq providers are listening to opp/cpufreq
> > notifiers, as to get an indication of when it could make sense to
> > change a performance state.
> >
> > In some cases the devfreq provider is also modeled as an interconnect
> > provider, allowing consumers to specify memory bandwidth constraints,
> > which may trigger a new performance state to be set for the memory
> > controller.
> >
> > In the tegra case, the memory controller is modelled as an
> > interconnect provider and the devfreq node is modelled as an
> > interconnect-consumer of the memory controller. Perhaps this can work
> > for apple SoCs too?
>
> I was poking around and noticed the OPP core can already integrate with
> interconnect requirements, so perhaps the memory controller can be an
> interconnect provider, and the CPU nodes can directly reference it as a
> consumer? This seems like a more accurate model of what the hardware
> does, and I think I saw some devices doing this already.
Yeah, that could work too. And, yes, I agree, it may be a better
description of the HW.
>
> (only problem is I have no idea of the actual bandwidth numbers involved
> here... I'll have to run some benchmarks to make sure this isn't just
> completely dummy data)
>
> >
> > That said, perhaps as an option to move forward, we can try to get the
> > cpufreq pieces solved first. Then as a step on top, add the
> > performance scaling for the memory controller?
>
> Sure; that's a pretty much independent part of this patchset, though I'm
> thinking I might as well try some things out for v2 anyway; if it looks
> like it'll take longer we can split it out and do just the cpufreq side.
In any case, I do my best to help with review.
Kind regards
Uffe
next prev parent reply other threads:[~2021-10-14 12:56 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-11 16:56 [RFC PATCH 0/9] Apple SoC CPU P-state switching Hector Martin
2021-10-11 16:56 ` [RFC PATCH 1/9] MAINTAINERS: apple: Add apple-mcc and clk-apple-cluster paths Hector Martin
2021-10-11 16:57 ` [RFC PATCH 2/9] dt-bindings: memory-controller: Add apple,mcc binding Hector Martin
2021-10-12 8:48 ` Krzysztof Kozlowski
2021-10-19 22:43 ` Rob Herring
2021-10-11 16:57 ` [RFC PATCH 3/9] dt-bindings: clock: Add apple,cluster-clk binding Hector Martin
2021-10-12 8:51 ` Krzysztof Kozlowski
2021-10-12 9:35 ` Viresh Kumar
[not found] ` <D0DE08FE-562E-4A48-BCA0-9094DAFCA564@marcan.st>
[not found] ` <20211012094302.3cownyzr4phxwifs@vireshk-i7>
[not found] ` <64584F8C-D49F-41B5-9658-CF8A25186E67@marcan.st>
[not found] ` <20211012095735.mhh2lzu52ohtotl6@vireshk-i7>
2021-10-12 13:48 ` Hector Martin
2021-10-11 16:57 ` [RFC PATCH 4/9] opp: core: Don't warn if required OPP device does not exist Hector Martin
2021-10-12 3:21 ` Viresh Kumar
2021-10-12 5:34 ` Hector Martin
2021-10-12 5:51 ` Viresh Kumar
2021-10-12 5:57 ` Hector Martin
2021-10-12 9:26 ` Viresh Kumar
2021-10-12 9:31 ` Hector Martin "marcan"
2021-10-12 9:32 ` Viresh Kumar
2021-10-14 6:52 ` Hector Martin
2021-10-14 6:56 ` Viresh Kumar
2021-10-14 7:03 ` Hector Martin
2021-10-14 7:22 ` Viresh Kumar
2021-10-14 7:23 ` Hector Martin
2021-10-14 11:08 ` Ulf Hansson
2021-10-14 9:55 ` Ulf Hansson
2021-10-14 11:43 ` Hector Martin
2021-10-14 12:55 ` Ulf Hansson [this message]
2021-10-14 17:02 ` Hector Martin
2021-10-15 11:26 ` Ulf Hansson
2021-10-11 16:57 ` [RFC PATCH 5/9] PM: domains: Add of_genpd_add_provider_simple_noclk() Hector Martin
2021-10-11 16:57 ` [RFC PATCH 6/9] memory: apple: Add apple-mcc driver to manage MCC perf in Apple SoCs Hector Martin
2021-10-12 9:19 ` Krzysztof Kozlowski
2021-10-14 6:59 ` Hector Martin
2021-10-14 7:36 ` Krzysztof Kozlowski
2021-10-14 7:52 ` Hector Martin
2021-10-14 8:04 ` Krzysztof Kozlowski
2021-10-14 8:31 ` Hector Martin
2021-10-11 16:57 ` [RFC PATCH 7/9] clk: apple: Add clk-apple-cluster driver to manage CPU p-states Hector Martin
[not found] ` <163424925931.1688384.9647104000291025081@swboyd.mtv.corp.google.com>
2021-10-17 9:16 ` Hector Martin
2021-10-11 16:57 ` [RFC PATCH 8/9] arm64: apple: Select MEMORY and APPLE_MCC Hector Martin
2021-10-11 16:57 ` [RFC PATCH 9/9] arm64: apple: Add CPU frequency scaling support for t8103 Hector Martin
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