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@xxxxxxxxxxxxxx>
> ---
> .../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@xxxxxxxxxxx/
