[PATCH v8 1/7] dt-bindings: devfreq: Add documentation for the interconnect properties

[Chanwoo Choi]

Hi Sylwester,

On Wed, Nov 4, 2020 at 7:37 PM Sylwester Nawrocki
<s.nawrocki at samsung.com> wrote:
>
> Add documentation for new optional properties in the exynos bus nodes:
> interconnects, #interconnect-cells, samsung,data-clock-ratio.
> 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 at samsung.com>
> Signed-off-by: Sylwester Nawrocki <s.nawrocki at samsung.com>
> ---
> Changes for v8:
>  - updated description of the interconnects property,
>  - fixed typo in samsung,data-clk-ratio property description.
>
> Changes for v7:
>  - bus-width property replaced with samsung,data-clock-ratio,
>  - the interconnect consumer bindings used instead of vendor specific
>    properties
>
> 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     | 71 +++++++++++++++++++++-
>  1 file changed, 69 insertions(+), 2 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/devfreq/exynos-bus.txt b/Documentation/devicetree/bindings/devfreq/exynos-bus.txt
> index e71f752..bcaa2c0 100644
> --- a/Documentation/devicetree/bindings/devfreq/exynos-bus.txt
> +++ b/Documentation/devicetree/bindings/devfreq/exynos-bus.txt
> @@ -51,6 +51,19 @@ 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 the interconnect functionality (QoS frequency
> +constraints):
> +- #interconnect-cells: should be 0.
> +- interconnects: as documented in ../interconnect.txt, describes a path at the
> +  higher level interconnects used by this interconnect provider.
> +  If this interconnect provider is directly linked to a top level interconnect
> +  provider the property contains only one phandle. The provider extends
> +  the interconnect graph by linking its node to a node registered by provider
> +  pointed to by first phandle in the 'interconnects' property.
> +
> +- samsung,data-clock-ratio: ratio of the data throughput in B/s to minimum data
> +   clock frequency in Hz, default value is 8 when this property is missing.
> +
>  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 +148,7 @@ 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 +197,7 @@ 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 +432,57 @@ 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>;
> +                       samsung,data-clock-ratio = <4>;
> +                       #interconnect-cells = <0>;
> +               };
> +
> +               bus_leftbus: bus_leftbus {
> +                       compatible = "samsung,exynos-bus";
> +                       clocks = <&clock CLK_DIV_GDL>;
> +                       clock-names = "bus";
> +                       operating-points-v2 = <&bus_leftbus_opp_table>;
> +                       #interconnect-cells = <0>;
> +                       interconnects = <&bus_dmc>;
> +               };
> +
> +               bus_display: bus_display {
> +                       compatible = "samsung,exynos-bus";
> +                       clocks = <&clock CLK_ACLK160>;
> +                       clock-names = "bus";
> +                       operating-points-v2 = <&bus_display_opp_table>;
> +                       #interconnect-cells = <0>;
> +                       interconnects = <&bus_leftbus &bus_dmc>;
> +               };
> +
> +               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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Acked-by: Chanwoo Choi <cw00.choi at samsung.com>

Thanks for your work.

-- 
Best Regards,
Chanwoo Choi