Re: [RFC PATCH v5 1/6] dt-bindings: exynos-bus: Add documentation for interconnect properties

Hi Sylwester,

On Sat, May 30, 2020 at 1:32 AM Sylwester Nawrocki s.nawrocki@samsung.com wrote:

Add documentation for new optional properties in the exynos bus nodes: samsung,interconnect-parent, #interconnect-cells. These properties allow to specify the SoC interconnect structure which then allows the interconnect consumer devices to request specific bandwidth requirements.

Signed-off-by: Artur Świgoń a.swigon@samsung.com Signed-off-by: Sylwester Nawrocki s.nawrocki@samsung.com

---

Changes for v5:

• exynos,interconnect-parent-node renamed to samsung,interconnect-parent

---

Documentation/devicetree/bindings/devfreq/exynos-bus.txt | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/Documentation/devicetree/bindings/devfreq/exynos-bus.txt b/Documentation/devicetree/bindings/devfreq/exynos-bus.txt index e71f752..e0d2daa 100644 --- a/Documentation/devicetree/bindings/devfreq/exynos-bus.txt +++ b/Documentation/devicetree/bindings/devfreq/exynos-bus.txt @@ -51,6 +51,11 @@ Optional properties only for parent bus device:

• exynos,saturation-ratio: the percentage value which is used to calibrate the performance count against total cycle count.

+Optional properties for interconnect functionality (QoS frequency constraints): +- samsung,interconnect-parent: phandle to the parent interconnect node; for

• passive devices should point to same node as the exynos,parent-bus property.

+- #interconnect-cells: should be 0

Detailed correlation between sub-blocks and power line according to Exynos SoC:

• In case of Exynos3250, there are two power line as following: VDD_MIF |--- DMC

@@ -185,8 +190,9 @@ Example1:

Example2 :

•   The bus of DMC (Dynamic Memory Controller) block in exynos3250.dtsi
  

•   is listed below:
  

•   The bus of DMC (Dynamic Memory Controller) block in exynos3250.dtsi is
  

•   listed below. An interconnect path "bus_lcd0 -- bus_leftbus -- bus_dmc"
  

•   is defined for demonstration purposes.
  
    bus_dmc: bus_dmc {
            compatible = "samsung,exynos-bus";
  

@@ -376,12 +382,15 @@ Example2 : &bus_dmc { devfreq-events = <&ppmu_dmc0_3>, <&ppmu_dmc1_3>; vdd-supply = <&buck1_reg>; /* VDD_MIF */

•           #interconnect-cells = <0>;
            status = "okay";
    };
  
    &bus_leftbus {
            devfreq-events = <&ppmu_leftbus_3>, <&ppmu_rightbus_3>;
            vdd-supply = <&buck3_reg>;
  

•           samsung,interconnect-parent = <&bus_dmc>;
  

•           #interconnect-cells = <0>;
            status = "okay";
    };
  
  

@@ -392,6 +401,8 @@ Example2 :

    &bus_lcd0 {
            devfreq = <&bus_leftbus>;

•           samsung,interconnect-parent = <&bus_leftbus>;
  

•           #interconnect-cells = <0>;
            status = "okay";
    };
  
  

-- 2.7.4

If you add the usage example like the mixer device of patch5 to this dt-binding document, I think it is very beneficial and more helpful for user of exynos-bus/exynos-generic-icc.

Acked-by: Chanwoo Choi cw00.choi@samsung.com

-- Best Regards, Chanwoo Choi Samsung Electronics