[v2,0/3] PM / Domains: Add support for assigned-performance-states

This is a re-spin of the series that was posted a while back [1]
with no major changes except for some review feedback from Stephen
addressed.

Back when this was posted, we thought its a good idea if client
drivers handle this instead of genpd core handling it [2]
So that lead to another series which handled this in the i2c 
driver [3], but then it looked like it would be duplication
of code across drivers and perhaps it should be done some place
centrally.

The way forward seems like
1. Get the bindings reviewed from DT folks
2. Once the bindings are finalized, figure out how to handle this
centrally without duplication. While this series does it with everything
handled in genpd core, there are perhaps other ways to do it with genpd
core exporting some helpers and genpd providers handling some of it with
callbacks.

----
Some devices within power-domains with performance states do not
support DVFS, but still need to vote on a default/static state
while they are active. Add support for a new device tree property
which the clients can use to specify this and add support in
kernel to parse this value and vote.

[1] https://lore.kernel.org/patchwork/patch/1284040/
[2] https://lore.kernel.org/patchwork/patch/1284042/
[3] https://lore.kernel.org/patchwork/patch/1356618/

Rajendra Nayak (3):
  dt-bindings: power: Introduce 'assigned-performance-states' property
  PM / Domains: Add support for 'assigned-performance-states'
  arm64: dts: sc7180: Add assigned-performance-states for i2c

 .../devicetree/bindings/power/power-domain.yaml    | 50 ++++++++++++++++++++++
 arch/arm64/boot/dts/qcom/sc7180.dtsi               | 24 +++++++++++
 drivers/base/power/domain.c                        | 27 ++++++++++++
 include/linux/pm_domain.h                          |  1 +
 4 files changed, 102 insertions(+)

On 27-05-21, 11:42, Rajendra Nayak wrote:
> While most devices within power-domains which support performance states,
> scale the performance state dynamically, some devices might want to
> set a static/default performance state while the device is active.
> These devices typically would also run off a fixed clock and not support
> dynamically scaling the device's performance, also known as DVFS techniques.
> Add a property 'assigned-performance-states' which client devices can
> use to set this default performance state on their power-domains.
> 
> Signed-off-by: Rajendra Nayak <rnayak@codeaurora.org>
> ---
>  .../devicetree/bindings/power/power-domain.yaml    | 50 ++++++++++++++++++++++
>  1 file changed, 50 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/power/power-domain.yaml b/Documentation/devicetree/bindings/power/power-domain.yaml
> index aed51e9..88cebf2 100644
> --- a/Documentation/devicetree/bindings/power/power-domain.yaml
> +++ b/Documentation/devicetree/bindings/power/power-domain.yaml
> @@ -66,6 +66,19 @@ properties:
>        by the given provider should be subdomains of the domain specified
>        by this binding.
>  
> +  assigned-performance-states:

Why is this named assigned and not "default"? Just curious :)

On Thu, 27 May 2021 11:42:27 +0530, Rajendra Nayak wrote:
> While most devices within power-domains which support performance states,
> scale the performance state dynamically, some devices might want to
> set a static/default performance state while the device is active.
> These devices typically would also run off a fixed clock and not support
> dynamically scaling the device's performance, also known as DVFS techniques.
> Add a property 'assigned-performance-states' which client devices can
> use to set this default performance state on their power-domains.
> 
> Signed-off-by: Rajendra Nayak <rnayak@codeaurora.org>
> ---
>  .../devicetree/bindings/power/power-domain.yaml    | 50 ++++++++++++++++++++++
>  1 file changed, 50 insertions(+)
> 

My bot found errors running 'make DT_CHECKER_FLAGS=-m dt_binding_check'
on your patch (DT_CHECKER_FLAGS is new in v5.13):

yamllint warnings/errors:
./Documentation/devicetree/bindings/power/power-domain.yaml:72:8: [warning] wrong indentation: expected 6 but found 7 (indentation)

dtschema/dtc warnings/errors:
Documentation/devicetree/bindings/power/power-domain.example.dt.yaml:0:0: /example-3/power-controller@43210000/opp-table: failed to match any schema with compatible: ['operating-points-v2']

See https://patchwork.ozlabs.org/patch/1484441

This check can fail if there are any dependencies. The base for a patch
series is generally the most recent rc1.

If you already ran 'make dt_binding_check' and didn't see the above
error(s), then make sure 'yamllint' is installed and dt-schema is up to
date:

pip3 install dtschema --upgrade

Please check and re-submit.

On Thu, 27 May 2021 at 08:13, Rajendra Nayak <rnayak@codeaurora.org> wrote:
>
> While most devices within power-domains which support performance states,
> scale the performance state dynamically, some devices might want to
> set a static/default performance state while the device is active.
> These devices typically would also run off a fixed clock and not support
> dynamically scaling the device's performance, also known as DVFS techniques.
> Add a property 'assigned-performance-states' which client devices can
> use to set this default performance state on their power-domains.
>
> Signed-off-by: Rajendra Nayak <rnayak@codeaurora.org>

I don't have a strong opinion about using "default-performance-state"
or "assigned-performance-state". Although, perhaps people can relate
to the existing "assigned-clock-rates" DT binding?
In any case, please add:

Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>

Kind regards
Uffe

> ---
>  .../devicetree/bindings/power/power-domain.yaml    | 50 ++++++++++++++++++++++
>  1 file changed, 50 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/power/power-domain.yaml b/Documentation/devicetree/bindings/power/power-domain.yaml
> index aed51e9..88cebf2 100644
> --- a/Documentation/devicetree/bindings/power/power-domain.yaml
> +++ b/Documentation/devicetree/bindings/power/power-domain.yaml
> @@ -66,6 +66,19 @@ properties:
>        by the given provider should be subdomains of the domain specified
>        by this binding.
>
> +  assigned-performance-states:
> +    $ref: /schemas/types.yaml#/definitions/uint32-array
> +    description:
> +       Some devices might need to configure their power domains in a default
> +       performance state while the device is active. These devices typically
> +       would also run off a fixed clock and not support dynamically scaling the
> +       device's performance, also known as DVFS techniques. The list of performance
> +       state values should correspond to the list of power domains specified as part
> +       of the power-domains property. Each cell corresponds to one power-domain.
> +       A value of 0 can be used for power-domains with no performance state
> +       requirement. In case the power-domains have OPP tables associated, the values
> +       here would typically match with one of the entries in the OPP table.
> +
>  required:
>    - "#power-domain-cells"
>
> @@ -131,3 +144,40 @@ examples:
>              min-residency-us = <7000>;
>          };
>      };
> +
> +  - |
> +    parent4: power-controller@12340000 {
> +        compatible = "foo,power-controller";
> +        reg = <0x12340000 0x1000>;
> +        #power-domain-cells = <0>;
> +    };
> +
> +    parent5: power-controller@43210000 {
> +        compatible = "foo,power-controller";
> +        reg = <0x43210000 0x1000>;
> +        #power-domain-cells = <0>;
> +        operating-points-v2 = <&power_opp_table>;
> +
> +        power_opp_table: opp-table {
> +            compatible = "operating-points-v2";
> +
> +            power_opp_low: opp1 {
> +                opp-level = <16>;
> +            };
> +
> +            rpmpd_opp_ret: opp2 {
> +                opp-level = <64>;
> +            };
> +
> +            rpmpd_opp_svs: opp3 {
> +                opp-level = <256>;
> +            };
> +        };
> +    };
> +
> +    child4: consumer@12341000 {
> +        compatible = "foo,consumer";
> +        reg = <0x12341000 0x1000>;
> +        power-domains = <&parent4>, <&parent5>;
> +        assigned-performance-states = <0>, <256>;
> +    };
> --
> QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member
> of Code Aurora Forum, hosted by The Linux Foundation
>

On 01-06-21, 13:12, Stephan Gerhold wrote:
> > +    child4: consumer@12341000 {
> > +        compatible = "foo,consumer";
> > +        reg = <0x12341000 0x1000>;
> > +        power-domains = <&parent4>, <&parent5>;
> > +        assigned-performance-states = <0>, <256>;
> > +    };
> 
> Bjorn already asked this in v1 [1]:
> 
> > May I ask how this is different from saying something like:
> >
> > 	required-opps = <&??>, <&rpmpd_opp_svs>;
> 
> and maybe this was already discussed further elsewhere. But I think at
> the very least we need some clarification in the commit message + the
> binding documentation how your new property relates to the existing
> "required-opps" binding.
> 
> Because even if it might not be implemented at the moment,
> Documentation/devicetree/bindings/power/power_domain.txt actually also
> specifies "required-opps" for device nodes e.g. with the following example:
> 
> 	leaky-device0@12350000 {
> 		compatible = "foo,i-leak-current";
> 		reg = <0x12350000 0x1000>;
> 		power-domains = <&power 0>;
> 		required-opps = <&domain0_opp_0>;
> 	};
> 
> It looks like Viresh added that in commit e856f078bcf1
> ("OPP: Introduce "required-opp" property").
> 
> And in general I think it's a bit inconsistent that we usually refer to
> performance states with phandles into the OPP table, but the
> assigned-performance-states suddenly use "raw numbers".

I must have missed that discussion, sorry about that.

The required-opps property, when present in device's node directly, is about the
(default) OPPs to choose for that device's normal functioning as they may not do
DVFS.

Good point Stephan.

On 02-06-21, 12:45, Ulf Hansson wrote:
> Alright, so it looks like we already have the DT binding that we need for this.
> 
> That leaves us with the question, at what place should we parse it
> (call of_get_required_opp_performance_state()) and set the performance
> state for the device?
> 
> Does it still make sense to do it while attaching the device to the
> genpd, you think?

For parsing, yes this is the right place. For getting that into
effect, whenever the device is supposed to work, i.e. with runtime PM
somehow.

On Wed, 2 Jun 2021 at 12:55, Viresh Kumar <viresh.kumar@linaro.org> wrote:
>
> On 02-06-21, 12:45, Ulf Hansson wrote:
> > Alright, so it looks like we already have the DT binding that we need for this.
> >
> > That leaves us with the question, at what place should we parse it
> > (call of_get_required_opp_performance_state()) and set the performance
> > state for the device?
> >
> > Does it still make sense to do it while attaching the device to the
> > genpd, you think?
>
> For parsing, yes this is the right place. For getting that into
> effect, whenever the device is supposed to work, i.e. with runtime PM
> somehow.

Okay, thanks for confirming. That would be along the lines of what
Rajendra did in patch2.

Kind regards
Uffe

On 6/15/2021 8:35 PM, Ulf Hansson wrote:
> On Thu, 27 May 2021 at 08:13, Rajendra Nayak <rnayak@codeaurora.org> wrote:
>>
>> While most devices within power-domains which support performance states,
>> scale the performance state dynamically, some devices might want to
>> set a static/default performance state while the device is active.
>> These devices typically would also run off a fixed clock and not support
>> dynamically scaling the device's performance, also known as DVFS techniques.
>> Add a property 'assigned-performance-states' which client devices can
>> use to set this default performance state on their power-domains.
>>
>> Signed-off-by: Rajendra Nayak <rnayak@codeaurora.org>
> 
> Rajendra, I think this is ready to be re-spinned on top of the latest
> changes for genpd that Rafael recently queued [1].

Thanks Ulf, yes, I plan to re-spin these based on the recent discussions,
re-using the existing required-opps bindings soon.
  
> If you would prefer me to do it, then please let me know. Otherwise I
> will be awaiting a new version from you.
> 
> Kind regards
> Uffe
> 
> [1]
> https://lore.kernel.org/linux-pm/CAJZ5v0i0FD-F7tN=AJNEY5HVVTCNuciLT4hCqdoS5bgF5WdmaA@mail.gmail.com/
> 
>> ---
>>   .../devicetree/bindings/power/power-domain.yaml    | 50 ++++++++++++++++++++++
>>   1 file changed, 50 insertions(+)
>>
>> diff --git a/Documentation/devicetree/bindings/power/power-domain.yaml b/Documentation/devicetree/bindings/power/power-domain.yaml
>> index aed51e9..88cebf2 100644
>> --- a/Documentation/devicetree/bindings/power/power-domain.yaml
>> +++ b/Documentation/devicetree/bindings/power/power-domain.yaml
>> @@ -66,6 +66,19 @@ properties:
>>         by the given provider should be subdomains of the domain specified
>>         by this binding.
>>
>> +  assigned-performance-states:
>> +    $ref: /schemas/types.yaml#/definitions/uint32-array
>> +    description:
>> +       Some devices might need to configure their power domains in a default
>> +       performance state while the device is active. These devices typically
>> +       would also run off a fixed clock and not support dynamically scaling the
>> +       device's performance, also known as DVFS techniques. The list of performance
>> +       state values should correspond to the list of power domains specified as part
>> +       of the power-domains property. Each cell corresponds to one power-domain.
>> +       A value of 0 can be used for power-domains with no performance state
>> +       requirement. In case the power-domains have OPP tables associated, the values
>> +       here would typically match with one of the entries in the OPP table.
>> +
>>   required:
>>     - "#power-domain-cells"
>>
>> @@ -131,3 +144,40 @@ examples:
>>               min-residency-us = <7000>;
>>           };
>>       };
>> +
>> +  - |
>> +    parent4: power-controller@12340000 {
>> +        compatible = "foo,power-controller";
>> +        reg = <0x12340000 0x1000>;
>> +        #power-domain-cells = <0>;
>> +    };
>> +
>> +    parent5: power-controller@43210000 {
>> +        compatible = "foo,power-controller";
>> +        reg = <0x43210000 0x1000>;
>> +        #power-domain-cells = <0>;
>> +        operating-points-v2 = <&power_opp_table>;
>> +
>> +        power_opp_table: opp-table {
>> +            compatible = "operating-points-v2";
>> +
>> +            power_opp_low: opp1 {
>> +                opp-level = <16>;
>> +            };
>> +
>> +            rpmpd_opp_ret: opp2 {
>> +                opp-level = <64>;
>> +            };
>> +
>> +            rpmpd_opp_svs: opp3 {
>> +                opp-level = <256>;
>> +            };
>> +        };
>> +    };
>> +
>> +    child4: consumer@12341000 {
>> +        compatible = "foo,consumer";
>> +        reg = <0x12341000 0x1000>;
>> +        power-domains = <&parent4>, <&parent5>;
>> +        assigned-performance-states = <0>, <256>;
>> +    };
>> --
>> QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member
>> of Code Aurora Forum, hosted by The Linux Foundation
>>