Re: [RFC 2/2] dt-bindings: mmc: sdhci-msm: Add Bus BW vote supported strings

Rob Herring
2019-09-13T14:36:15Z

On Fri, Sep 06, 2019 at 06:17:17PM +0530, Pradeep P V K wrote:
> Add Bus bandwidth voting supported strings for qcom-sdhci controller.

What is bus bandwidth voting?

>
> Signed-off-by: Pradeep P V K <ppvk@codeaurora.org>
> ---
> .../devicetree/bindings/mmc/sdhci-msm.txt | 32 ++++++++++++++++++++++
> 1 file changed, 32 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/mmc/sdhci-msm.txt b/Documentation/devicetree/bindings/mmc/sdhci-msm.txt
> index da4edb1..8255d92 100644
> --- a/Documentation/devicetree/bindings/mmc/sdhci-msm.txt
> +++ b/Documentation/devicetree/bindings/mmc/sdhci-msm.txt
> @@ -39,6 +39,25 @@ Required properties:
> "cal" - reference clock for RCLK delay calibration (optional)
> "sleep" - sleep clock for RCLK delay calibration (optional)
>
> +Optional Properties:
> +* Following bus parameters are required for bus bw voting:
> +- interconnects: Pairs of phandles and interconnect provider specifier
> + to denote the edge source and destination ports of
> + the interconnect path. Please refer to
> + Documentation/devicetree/bindings/interconnect/
> + for more details.
> +- interconnect-names: List of interconnect path name strings sorted in the same
> + order as the interconnects property. Consumers drivers will use
> + interconnect-names to match interconnect paths with interconnect
> + specifiers. Please refer to Documentation/devicetree/bindings/
> + interconnect/ for more details.

How many? What are the strings?

> +- qcom,msm-bus,name: string describing the bus path
> +- qcom,msm-bus,num-cases: number of configurations in which sdhc can operate in
> +- qcom,msm-bus,num-paths: number of paths to vote for
> +- qcom,msm-bus,vectors-KBps: Takes a tuple <ib ab>, <ib ab> (2 tuples for 2

ib and ab are what? Didn't we just add interconnect bindings for
expressing bandwidth?

> + num-paths) The number of these entries *must*
> + be same as num-cases.

Are all these properties SDHCI specific or can we expect to get these
for *all* the QCom blocks?

> +
> Example:
>
> sdhc_1: sdhci@f9824900 {
> @@ -56,6 +75,19 @@ Example:
>
> clocks = <&gcc GCC_SDCC1_APPS_CLK>, <&gcc GCC_SDCC1_AHB_CLK>;
> clock-names = "core", "iface";
> + interconnects = <&qnoc 50 &qnoc 512>,
> + <&qnoc 1 &qnoc 544>;
> + interconnect-names = "sdhc-ddr","cpu-sdhc";
> + qcom,msm-bus,name = "sdhc1";
> + qcom,msm-bus,num-cases = <3>;
> + qcom,msm-bus,num-paths = <2>;
> + qcom,msm-bus,vectors-KBps =
> + /* No Vote */
> + <0 0>, <0 0>,
> + /* 50 MB/s */
> + <130718 200000>, <133320 133320>,
> + /* 200 MB/s */
> + <1338562 4096000>, <1338562 4096000>;
> };
>
> sdhc_2: sdhci@f98a4900 {
> --
> 1.9.1
>