Thread (6 messages) 6 messages, 2 authors, 2020-12-09
STALE2027d
Revisions (5)
  1. v4 [diff vs current]
  2. v5 current
  3. v6 [diff vs current]
  4. v7 [diff vs current]
  5. v8 [diff vs current]

[PATCH v5 1/4] dt-bindings: opp: Allow empty OPP tables

From: Nicola Mazzucato <hidden>
Date: 2020-12-08 17:42:28
Also in: linux-devicetree, linux-pm, lkml
Subsystem: open firmware and flattened device tree bindings, operating performance points (opp), the rest · Maintainers: Rob Herring, Krzysztof Kozlowski, Conor Dooley, Viresh Kumar, Nishanth Menon, Stephen Boyd, Linus Torvalds

Currently the optional property opp-shared is used within an opp table
to tell that a set of devices share their clock/voltage lines (and the
OPP points).
It is therefore possible to use an empty OPP table to convey only that
information, useful in situations where the opp points are provided via
other means (hardware. firmware, etc).

Update the documentation to remark this additional case and provide an
example.

Signed-off-by: Nicola Mazzucato <redacted>
---
 Documentation/devicetree/bindings/opp/opp.txt | 54 ++++++++++++++++++-
 1 file changed, 53 insertions(+), 1 deletion(-)
diff --git a/Documentation/devicetree/bindings/opp/opp.txt b/Documentation/devicetree/bindings/opp/opp.txt
index 9847dfeeffcb..08b3da4736cf 100644
--- a/Documentation/devicetree/bindings/opp/opp.txt
+++ b/Documentation/devicetree/bindings/opp/opp.txt
@@ -65,7 +65,9 @@ Required properties:
 
 - OPP nodes: One or more OPP nodes describing voltage-current-frequency
   combinations. Their name isn't significant but their phandle can be used to
-  reference an OPP.
+  reference an OPP. These are mandatory except for the case where the OPP table
+  is present only to indicate dependency between devices using the opp-shared
+  property.
 
 Optional properties:
 - opp-shared: Indicates that device nodes using this OPP Table Node's phandle
@@ -568,3 +570,53 @@ Example 6: opp-microvolt-<name>, opp-microamp-<name>:
 		};
 	};
 };
+
+Example 7: Single cluster Quad-core ARM cortex A53, OPP points from firmware,
+distinct clock controls but two sets of clock/voltage/current lines.
+
+/ {
+	cpus {
+		#address-cells = <2>;
+		#size-cells = <0>;
+
+		cpu@0 {
+			compatible = "arm,cortex-a53";
+			reg = <0x0 0x100>;
+			next-level-cache = <&A53_L2>;
+			clocks = <&dvfs_controller 0>;
+			operating-points-v2 = <&cpu_opp0_table>;
+		};
+		cpu@1 {
+			compatible = "arm,cortex-a53";
+			reg = <0x0 0x101>;
+			next-level-cache = <&A53_L2>;
+			clocks = <&dvfs_controller 1>;
+			operating-points-v2 = <&cpu_opp0_table>;
+		};
+		cpu@2 {
+			compatible = "arm,cortex-a53";
+			reg = <0x0 0x102>;
+			next-level-cache = <&A53_L2>;
+			clocks = <&dvfs_controller 2>;
+			operating-points-v2 = <&cpu_opp1_table>;
+		};
+		cpu@3 {
+			compatible = "arm,cortex-a53";
+			reg = <0x0 0x103>;
+			next-level-cache = <&A53_L2>;
+			clocks = <&dvfs_controller 3>;
+			operating-points-v2 = <&cpu_opp1_table>;
+		};
+
+	};
+
+	cpu_opp0_table: opp0_table {
+		compatible = "operating-points-v2";
+		opp-shared;
+	};
+
+	cpu_opp1_table: opp1_table {
+		compatible = "operating-points-v2";
+		opp-shared;
+	};
+};
-- 
2.27.0


_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
Keyboard shortcuts
hback out one level
jnext message in thread
kprevious message in thread
ldrill in
Escclose help / fold thread tree
?toggle this help