On 1/15/2021 9:45 PM, Bjorn Andersson wrote:

On Thu 24 Dec 05:12 CST 2020, Roja Rani Yarubandi wrote:

quoted

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: Roja Rani Yarubandi <redacted>
---
  .../bindings/power/power-domain.yaml          | 49 +++++++++++++++++++
  1 file changed, 49 insertions(+)

diff --git a/Documentation/devicetree/bindings/power/power-domain.yaml b/Documentation/devicetree/bindings/power/power-domain.yaml
index aed51e9dcb11..a42977a82d06 100644
--- a/Documentation/devicetree/bindings/power/power-domain.yaml
+++ b/Documentation/devicetree/bindings/power/power-domain.yaml

@@ -66,6 +66,18 @@ 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 typcially
+       would also run off a fixed clock and not support dynamically scaling
+       the device's performance, also known as DVFS techniques. Each cell in
+       performance state value corresponds to one power domain specified as
+       part of the power-domains property. Performance state value can be an
+       opp-level inside an OPP table of the power-domain and need not match
+       with any OPP table performance state.
+
  required:
    - "#power-domain-cells"
  

@@ -131,3 +143,40 @@ 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>;

May I ask how this is different from saying something like:

	required-opps = <&??>, <&rpmpd_opp_svs>:

I think its potentially the same. We just don't have any code to handle this
binding in kernel yet (when this property is part of the device/consumer node)

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