On Thu, Jul 02, 2020 at 06:37:19PM +0200, Sylwester Nawrocki wrote:
> Add documentation for new optional properties in the exynos bus nodes:
> samsung,interconnect-parent, #interconnect-cells, bus-width.
> 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@xxxxxxxxxxx>
> Signed-off-by: Sylwester Nawrocki <s.nawrocki@xxxxxxxxxxx>
> ---
> Changes for v6:
> - added dts example of bus hierarchy definition and the interconnect
> consumer,
> - added new bus-width property.
>
> Changes for v5:
> - exynos,interconnect-parent-node renamed to samsung,interconnect-parent
> ---
> .../devicetree/bindings/devfreq/exynos-bus.txt | 68 +++++++++++++++++++++-
> 1 file changed, 66 insertions(+), 2 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/devfreq/exynos-bus.txt b/Documentation/devicetree/bindings/devfreq/exynos-bus.txt
> index e71f752..4035e3e 100644
> --- a/Documentation/devicetree/bindings/devfreq/exynos-bus.txt
> +++ b/Documentation/devicetree/bindings/devfreq/exynos-bus.txt
> @@ -51,6 +51,13 @@ 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.
Adding vendor specific properties for a common binding defeats the
point.
> +- #interconnect-cells: should be 0.
> +- bus-width: the interconnect bus width in bits, default value is 8 when this
> + property is missing.
Your bus is 8-bits or 4-bits as the example?
> +
> 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
> @@ -135,7 +142,7 @@ Detailed correlation between sub-blocks and power line according to Exynos SoC:
> |--- PERIC (Fixed clock rate)
> |--- FSYS (Fixed clock rate)
>
> -Example1:
> +Example 1:
> Show the AXI buses of Exynos3250 SoC. Exynos3250 divides the buses to
> power line (regulator). The MIF (Memory Interface) AXI bus is used to
> transfer data between DRAM and CPU and uses the VDD_MIF regulator.
> @@ -184,7 +191,7 @@ Example1:
> |L5 |200000 |200000 |400000 |300000 | ||1000000 |
> ----------------------------------------------------------
>
> -Example2 :
> +Example 2:
> The bus of DMC (Dynamic Memory Controller) block in exynos3250.dtsi
> is listed below:
>
> @@ -419,3 +426,60 @@ Example2 :
> devfreq = <&bus_leftbus>;
> status = "okay";
> };
> +
> +Example 3:
> + An interconnect path "bus_display -- bus_leftbus -- bus_dmc" on
> + Exynos4412 SoC with video mixer as an interconnect consumer device.
> +
> + soc {
> + bus_dmc: bus_dmc {
> + compatible = "samsung,exynos-bus";
> + clocks = <&clock CLK_DIV_DMC>;
> + clock-names = "bus";
> + operating-points-v2 = <&bus_dmc_opp_table>;
> + bus-width = <4>;
> + #interconnect-cells = <0>;
> + status = "disabled";
> + };
> +
> + bus_leftbus: bus_leftbus {
> + compatible = "samsung,exynos-bus";
> + clocks = <&clock CLK_DIV_GDL>;
> + clock-names = "bus";
> + operating-points-v2 = <&bus_leftbus_opp_table>;
> + samsung,interconnect-parent = <&bus_dmc>;
> + #interconnect-cells = <0>;
> + status = "disabled";
> + };
> +
> + bus_display: bus_display {
> + compatible = "samsung,exynos-bus";
> + clocks = <&clock CLK_ACLK160>;
> + clock-names = "bus";
> + operating-points-v2 = <&bus_display_opp_table>;
> + samsung,interconnect-parent = <&bus_leftbus>;
> + #interconnect-cells = <0>;
> + status = "disabled";
> + };
> +
> + bus_dmc_opp_table: opp_table1 {
> + compatible = "operating-points-v2";
> + /* ... */
> + }
> +
> + bus_leftbus_opp_table: opp_table3 {
> + compatible = "operating-points-v2";
> + /* ... */
> + };
> +
> + bus_display_opp_table: opp_table4 {
> + compatible = "operating-points-v2";
> + /* .. */
> + };
> +
> + &mixer {
> + compatible = "samsung,exynos4212-mixer";
> + interconnects = <&bus_display &bus_dmc>;
> + /* ... */
> + };
> + };
> --
> 2.7.4
>
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