linux-kernel - Re: [PATCH 09/16] dt-bindings: firmware: arm,scmi: Extend bindings for protocol@13

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAL_Jsq+GMA62hey6+KYMmVSWsDEkGfD0B=0V9AbdmRqdE6VW1g@mail.gmail.com>
Date:   Fri, 14 Jul 2023 11:14:50 -0600
From:   Rob Herring <robh@...nel.org>
To:     Ulf Hansson <ulf.hansson@...aro.org>
Cc:     Sudeep Holla <sudeep.holla@....com>,
        Cristian Marussi <cristian.marussi@....com>,
        Viresh Kumar <vireshk@...nel.org>, Nishanth Menon <nm@...com>,
        Stephen Boyd <sboyd@...nel.org>,
        Nikunj Kela <nkela@...cinc.com>,
        Prasad Sodagudi <psodagud@...cinc.com>,
        Alexandre Torgue <alexandre.torgue@...s.st.com>,
        linux-pm@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>, devicetree@...r.kernel.org
Subject: Re: [PATCH 09/16] dt-bindings: firmware: arm,scmi: Extend bindings
 for protocol@13

On Thu, Jun 15, 2023 at 3:11 AM Ulf Hansson <ulf.hansson@...aro.org> wrote:
>
> On Thu, 15 Jun 2023 at 01:00, Rob Herring <robh@...nel.org> wrote:
> >
> > On Wed, Jun 07, 2023 at 02:46:21PM +0200, Ulf Hansson wrote:
> > > The protocol@13 node is describing the performance scaling option for the
> > > ARM SCMI interface, as a clock provider. This is unnecessary limiting, as
> > > performance scaling is in many cases not limited to switching a clock's
> > > frequency.
> > >
> > > Therefore, let's extend the binding so the interface can be modelled as a
> > > generic "performance domain" too. The common way to describe this, is to
> > > use the "power-domain" bindings, so let's use that.
> >
> > What's wrong with the performance-domain binding?
>
> In my opinion I think the performance-domain binding is superfluous.
> We already have plenty of power-domains that do performance scaling
> too - and they stick with the power-domain binding, as it's
> sufficient.

IMO, power-domains should be for power islands which can be power
gated. I know they are abused though. Of course, when things are
hidden in firmware, you don't really know. A power-domain could be
just a clock or a clock could be multiple physical clocks.

> That said, I would rather follow the defacto standard that has been
> used for many years in the kernel. Do you have a preference that we
> should stick to?

If power-domains are sufficient, then why do we have
performance-domains? We need clear rules for when to use what.

Rob