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Message-ID: <6751ea7e.050a0220.3435c6.5c62@mx.google.com>
Date: Thu, 5 Dec 2024 19:01:30 +0100
From: Christian Marangi <ansuelsmth@...il.com>
To: Ulf Hansson <ulf.hansson@...aro.org>
Cc: "Rafael J. Wysocki" <rafael@...nel.org>,
Viresh Kumar <viresh.kumar@...aro.org>,
Rob Herring <robh@...nel.org>,
Krzysztof Kozlowski <krzk+dt@...nel.org>,
Conor Dooley <conor+dt@...nel.org>, linux-pm@...r.kernel.org,
devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
upstream@...oha.com
Subject: Re: [PATCH v6 1/2] dt-bindings: cpufreq: Document support for Airoha
EN7581 CPUFreq
On Thu, Dec 05, 2024 at 05:07:07PM +0100, Ulf Hansson wrote:
> On Wed, 4 Dec 2024 at 19:24, Christian Marangi <ansuelsmth@...il.com> wrote:
> >
> > Document required property for Airoha EN7581 CPUFreq .
> >
> > On newer Airoha SoC, CPU Frequency is scaled indirectly with SMCCC commands
> > to ATF and no clocks are exposed to the OS.
> >
> > The SoC have performance state described by ID for each OPP, for this a
> > Power Domain is used that sets the performance state ID according to the
> > required OPPs defined in the CPU OPP tables.
>
> To clarify this, I would rather speak about a performance-domain with
> performance-levels, where each level corresponds to a frequency that
> is controlled by the FW/HW.
(If Rob notice this and gets angry :P , v6 was posted 10 minutes before
the review from Rob, big coincidence. No intention of ignoring the
comments)
I notice that power-domain schema also accepts node with
performance-domain. My concern is that the API we would use
(power-domain related) expect #power-domain-cells property and might
reject init with #power-performance-cells.
I have to check this but I think it's better to have a clear idea of
what the schema should be.
>
> >
> > Signed-off-by: Christian Marangi <ansuelsmth@...il.com>
> > Reviewed-by: Ulf Hansson <ulf.hansson@...aro.org>
> > ---
> > Changes v6:
> > - No changes
> > Changes v5:
> > - Add Reviewed-by tag
> > - Fix OPP node name error
> > - Rename cpufreq node name to power-domain
> > - Rename CPU node power domain name to perf
> > - Add model and compatible to example
> > Changes v4:
> > - Add this patch
> >
> > .../cpufreq/airoha,en7581-cpufreq.yaml | 262 ++++++++++++++++++
> > 1 file changed, 262 insertions(+)
> > create mode 100644 Documentation/devicetree/bindings/cpufreq/airoha,en7581-cpufreq.yaml
> >
> > diff --git a/Documentation/devicetree/bindings/cpufreq/airoha,en7581-cpufreq.yaml b/Documentation/devicetree/bindings/cpufreq/airoha,en7581-cpufreq.yaml
> > new file mode 100644
> > index 000000000000..7e36fa037e4b
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/cpufreq/airoha,en7581-cpufreq.yaml
> > @@ -0,0 +1,262 @@
> > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/cpufreq/airoha,en7581-cpufreq.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: Airoha EN7581 CPUFreq
> > +
> > +maintainers:
> > + - Christian Marangi <ansuelsmth@...il.com>
> > +
> > +description: |
> > + On newer Airoha SoC, CPU Frequency is scaled indirectly with SMCCC commands
> > + to ATF and no clocks are exposed to the OS.
> > +
> > + The SoC have performance state described by ID for each OPP, for this a
> > + Power Domain is used that sets the performance state ID according to the
> > + required OPPs defined in the CPU OPP tables.
> > +
> > +properties:
> > + compatible:
> > + const: airoha,en7581-cpufreq
> > +
> > + '#clock-cells':
> > + const: 0
>
> I think Rob questioned this too. Why do we need a clock provider here?
>
> If this is only to keep the CPUfreq DT driver happy, I think this
> should be dropped. There is only a performance-domain here, right?
>
As said in v5, the API is fun.
SMC have an OP to request the current frequency and that is provided in
MHz.
Then it does have a command to se the global frequency and that is in
Index.
Each index rapresent a particular frequency.
For CPUFreq-DT a clock is mandatory, and is also good to provide one.
But in v5 Rob was O.K. for the clock. The main complain is for the OPP
table.
> > +
> > + '#power-domain-cells':
> > + const: 0
> > +
> > + operating-points-v2: true
> > +
> > +required:
> > + - compatible
> > + - '#clock-cells'
> > + - '#power-domain-cells'
> > + - operating-points-v2
> > +
> > +additionalProperties: false
> > +
> > +examples:
> > + - |
> > + / {
> > + model = "Airoha EN7581 Evaluation Board";
> > + compatible = "airoha,en7581-evb", "airoha,en7581";
> > +
> > + #address-cells = <2>;
> > + #size-cells = <2>;
> > +
> > + cpus {
> > + #address-cells = <1>;
> > + #size-cells = <0>;
> > +
> > + cpu0: cpu@0 {
> > + device_type = "cpu";
> > + compatible = "arm,cortex-a53";
> > + reg = <0x0>;
> > + operating-points-v2 = <&cpu_opp_table>;
> > + enable-method = "psci";
> > + clocks = <&cpu_pd>;
> > + clock-names = "cpu";
> > + power-domains = <&cpu_pd>;
> > + power-domain-names = "perf";
> > + next-level-cache = <&l2>;
> > + #cooling-cells = <2>;
> > + };
> > +
> > + cpu1: cpu@1 {
> > + device_type = "cpu";
> > + compatible = "arm,cortex-a53";
> > + reg = <0x1>;
> > + operating-points-v2 = <&cpu_opp_table>;
> > + enable-method = "psci";
> > + clocks = <&cpu_pd>;
> > + clock-names = "cpu";
> > + power-domains = <&cpu_pd>;
> > + power-domain-names = "perf";
> > + next-level-cache = <&l2>;
> > + #cooling-cells = <2>;
> > + };
> > +
> > + cpu2: cpu@2 {
> > + device_type = "cpu";
> > + compatible = "arm,cortex-a53";
> > + reg = <0x2>;
> > + operating-points-v2 = <&cpu_opp_table>;
> > + enable-method = "psci";
> > + clocks = <&cpu_pd>;
> > + clock-names = "cpu";
> > + power-domains = <&cpu_pd>;
> > + power-domain-names = "perf";
> > + next-level-cache = <&l2>;
> > + #cooling-cells = <2>;
> > + };
> > +
> > + cpu3: cpu@3 {
> > + device_type = "cpu";
> > + compatible = "arm,cortex-a53";
> > + reg = <0x3>;
> > + operating-points-v2 = <&cpu_opp_table>;
> > + enable-method = "psci";
> > + clocks = <&cpu_pd>;
> > + clock-names = "cpu";
> > + power-domains = <&cpu_pd>;
> > + power-domain-names = "perf";
> > + next-level-cache = <&l2>;
> > + #cooling-cells = <2>;
> > + };
> > + };
> > +
> > + cpu_opp_table: opp-table-cpu {
> > + compatible = "operating-points-v2";
> > + opp-shared;
> > +
> > + opp-500000000 {
> > + opp-hz = /bits/ 64 <500000000>;
> > + required-opps = <&smcc_opp0>;
> > + };
> > +
> > + opp-550000000 {
> > + opp-hz = /bits/ 64 <550000000>;
> > + required-opps = <&smcc_opp1>;
> > + };
> > +
> > + opp-600000000 {
> > + opp-hz = /bits/ 64 <600000000>;
> > + required-opps = <&smcc_opp2>;
> > + };
> > +
> > + opp-650000000 {
> > + opp-hz = /bits/ 64 <650000000>;
> > + required-opps = <&smcc_opp3>;
> > + };
> > +
> > + opp-7000000000 {
> > + opp-hz = /bits/ 64 <700000000>;
> > + required-opps = <&smcc_opp4>;
> > + };
> > +
> > + opp-7500000000 {
> > + opp-hz = /bits/ 64 <750000000>;
> > + required-opps = <&smcc_opp5>;
> > + };
> > +
> > + opp-8000000000 {
> > + opp-hz = /bits/ 64 <800000000>;
> > + required-opps = <&smcc_opp6>;
> > + };
> > +
> > + opp-8500000000 {
> > + opp-hz = /bits/ 64 <850000000>;
> > + required-opps = <&smcc_opp7>;
> > + };
> > +
> > + opp-9000000000 {
> > + opp-hz = /bits/ 64 <900000000>;
> > + required-opps = <&smcc_opp8>;
> > + };
> > +
> > + opp-9500000000 {
> > + opp-hz = /bits/ 64 <950000000>;
> > + required-opps = <&smcc_opp9>;
> > + };
> > +
> > + opp-10000000000 {
> > + opp-hz = /bits/ 64 <1000000000>;
> > + required-opps = <&smcc_opp10>;
> > + };
> > +
> > + opp-10500000000 {
> > + opp-hz = /bits/ 64 <1050000000>;
> > + required-opps = <&smcc_opp11>;
> > + };
> > +
> > + opp-11000000000 {
> > + opp-hz = /bits/ 64 <1100000000>;
> > + required-opps = <&smcc_opp12>;
> > + };
> > +
> > + opp-11500000000 {
> > + opp-hz = /bits/ 64 <1150000000>;
> > + required-opps = <&smcc_opp13>;
> > + };
> > +
> > + opp-12000000000 {
> > + opp-hz = /bits/ 64 <1200000000>;
> > + required-opps = <&smcc_opp14>;
> > + };
> > + };
> > +
> > + cpu_smcc_opp_table: opp-table-smcc {
> > + compatible = "operating-points-v2";
> > +
> > + smcc_opp0: opp-0 {
> > + opp-level = <0>;
> > + };
> > +
> > + smcc_opp1: opp-1 {
> > + opp-level = <1>;
> > + };
> > +
> > + smcc_opp2: opp-2 {
> > + opp-level = <2>;
> > + };
> > +
> > + smcc_opp3: opp-3 {
> > + opp-level = <3>;
> > + };
> > +
> > + smcc_opp4: opp-4 {
> > + opp-level = <4>;
> > + };
> > +
> > + smcc_opp5: opp-5 {
> > + opp-level = <5>;
> > + };
> > +
> > + smcc_opp6: opp-6 {
> > + opp-level = <6>;
> > + };
> > +
> > + smcc_opp7: opp-7 {
> > + opp-level = <7>;
> > + };
> > +
> > + smcc_opp8: opp-8 {
> > + opp-level = <8>;
> > + };
> > +
> > + smcc_opp9: opp-9 {
> > + opp-level = <9>;
> > + };
> > +
> > + smcc_opp10: opp-10 {
> > + opp-level = <10>;
> > + };
> > +
> > + smcc_opp11: opp-11 {
> > + opp-level = <11>;
> > + };
> > +
> > + smcc_opp12: opp-12 {
> > + opp-level = <12>;
> > + };
> > +
> > + smcc_opp13: opp-13 {
> > + opp-level = <13>;
> > + };
> > +
> > + smcc_opp14: opp-14 {
> > + opp-level = <14>;
> > + };
> > + };
> > +
> > + cpu_pd: power-domain {
>
> Nitpick: We could use the name *performance-domain* here instead, that
> would make it even more clear what this node describes.
>
> > + compatible = "airoha,en7581-cpufreq";
> > +
> > + operating-points-v2 = <&cpu_smcc_opp_table>;
> > +
> > + #power-domain-cells = <0>;
> > + #clock-cells = <0>;
> > + };
> > + };
> > --
> > 2.45.2
> >
>
> With those changes I am still happy with this approach, so feel free
> to keep my Reviewed-by tag.
>
Thanks a lot for the hint. What I think should be understood and we need
to agree on is the OPP table.
Currently we have an implementation that is
CPU-OPP-Table:
- OPP Freq in MHz 1
- connection to OPP for performance-domain
...
Performance-Domain-OPP-Table:
- OPP Level 1 (connected to OPP Freq)
Is the double table the problem and we should find a way to unify it in
something like
CPU-OPP-Table:
- OPP Freq in MHz 1
OPP Level 1
- OPP Freq in MHz 2
OPP Level 2
...
>From what I notice this is problematic as the 2 subsystems require
dedicated table for each other.
In any case I think a table of freq is a MUST. Dropping that would
result in not giving to the user an idea of the supported frequency and
scaling stats.
--
Ansuel
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