From: Stephan Gerhold <stephan@gerhold.net>
To: Rajendra Nayak <rnayak@codeaurora.org>
Cc: ulf.hansson@linaro.org, robh+dt@kernel.org,
bjorn.andersson@linaro.org, viresh.kumar@linaro.org,
linux-pm@vger.kernel.org, devicetree@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org,
swboyd@chromium.org, rojay@codeaurora.org
Subject: Re: [PATCH v2 1/3] dt-bindings: power: Introduce 'assigned-performance-states' property
Date: Tue, 1 Jun 2021 13:12:45 +0200 [thread overview]
Message-ID: <YLYV3ov/iBffZMg4@gerhold.net> (raw)
In-Reply-To: <1622095949-2014-2-git-send-email-rnayak@codeaurora.org>
Hi,
On Thu, May 27, 2021 at 11:42:27AM +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(+)
>
> 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.
> +
Is it just me or is this actually in the wrong place here?
Given that #power-domain-cells is required this looks like the bindings
for power domain providers, not consumers. :)
It looks like the consumer bindings are still in
Documentation/devicetree/bindings/power/power_domain.txt
> 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>;
> + };
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".
Stephan
[1]: https://lore.kernel.org/linux-arm-msm/YAG%2FpNXQOS+C2zLr@builder.lan/
next prev parent reply other threads:[~2021-06-01 11:13 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-27 6:12 [PATCH v2 0/3] PM / Domains: Add support for assigned-performance-states Rajendra Nayak
2021-05-27 6:12 ` [PATCH v2 1/3] dt-bindings: power: Introduce 'assigned-performance-states' property Rajendra Nayak
2021-05-27 6:16 ` Viresh Kumar
2021-05-27 6:21 ` Rajendra Nayak
2021-05-27 14:23 ` Rob Herring
2021-05-27 14:26 ` Rob Herring
2021-06-01 10:33 ` Ulf Hansson
2021-06-01 11:12 ` Stephan Gerhold [this message]
2021-06-01 11:44 ` Viresh Kumar
2021-06-02 10:45 ` Ulf Hansson
2021-06-02 10:54 ` Viresh Kumar
2021-06-02 12:50 ` Ulf Hansson
2021-06-15 15:05 ` Ulf Hansson
2021-06-18 6:01 ` Rajendra Nayak
2021-05-27 6:12 ` [PATCH v2 2/3] PM / Domains: Add support for 'assigned-performance-states' Rajendra Nayak
2021-05-27 6:12 ` [PATCH v2 3/3] arm64: dts: sc7180: Add assigned-performance-states for i2c Rajendra Nayak
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