Re: [PATCH 1/2] dt-bindings: interconnect: Update Qualcomm SDM845 DT bindings

[David Dai <daidavid1@xxxxxxxxxxxxxx>]

Thanks for the feedback Stephen, much appreciated!

On 7/23/2019 7:42 AM, Stephen Boyd wrote:
> Quoting David Dai (2019-07-19 13:32:23)
> > Redefine the Network-on-Chip devices to more accurately describe
> > the interconnect topology on Qualcomm's SDM845 platform. Each
> > interconnect device can communicate with different instances of the
> > RPMh hardware which are described as RSCs(Resource State Coordinators).
> >
> > Signed-off-by: David Dai <daidavid1@xxxxxxxxxxxxxx>
> > ---
> > diff --git a/Documentation/devicetree/bindings/interconnect/qcom,bcm-voter.txt b/Documentation/devicetree/bindings/interconnect/qcom,bcm-voter.txt
> > new file mode 100644
> > index 0000000..2cf7da2
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/interconnect/qcom,bcm-voter.txt
> > @@ -0,0 +1,32 @@
> > +Qualcomm BCM-Voter interconnect driver binding
> > +-----------------------------------------------------------
> > +
> > +The Bus Clock Manager (BCM) is a dedicated hardware accelerator
> > +that manages shared system resources by aggregating requests
> > +from multiple Resource State Coordinators (RSC). Interconnect
> > +providers are able to vote for aggregated thresholds values from
> > +consumers by communicating through their respective RSCs.
> > +
> > +Required properties :
> > +- compatible : shall contain only one of the following:
> > +                       "qcom,sdm845-bcm-voter",
> > +
> > +Examples:
> > +
> > +apps_rsc: rsc@179c0000 {
> But there isn't a reg property.
I'll change this to the generic example with just apps_rsc: rsc {
> > +       label = "apps_rsc";
> Is label required?
>
> > +       compatible = "qcom,rpmh-rsc";
> > +
> > +       apps_bcm_voter: bcm_voter {
> > +               compatible = "qcom,sdm845-bcm-voter";
> > +       };
> > +}
> > +
> > +disp_rsc: rsc@179d0000 {
> > +       label = "disp_rsc";
> > +       compatible = "qcom,rpmh-rsc";
> > +
> > +       disp_bcm_voter: bcm_voter {
> > +               compatible = "qcom,sdm845-bcm-voter";
> > +       };
> > +}
> > diff --git a/Documentation/devicetree/bindings/interconnect/qcom,sdm845.txt b/Documentation/devicetree/bindings/interconnect/qcom,sdm845.txt
> > index 5c4f1d9..27f9ed9 100644
> > --- a/Documentation/devicetree/bindings/interconnect/qcom,sdm845.txt
> > +++ b/Documentation/devicetree/bindings/interconnect/qcom,sdm845.txt
> > @@ -4,21 +4,43 @@ Qualcomm SDM845 Network-On-Chip interconnect driver binding
> >   SDM845 interconnect providers support system bandwidth requirements through
> >   RPMh hardware accelerators known as Bus Clock Manager (BCM). The provider is
> >   able to communicate with the BCM through the Resource State Coordinator (RSC)
> > -associated with each execution environment. Provider nodes must reside within
> > -an RPMh device node pertaining to their RSC and each provider maps to a single
> > -RPMh resource.
> > +associated with each execution environment. Provider nodes must point to at
> > +least one RPMh device child node pertaining to their RSC and each provider
> > +can map to multiple RPMh resources.
> >   
> >   Required properties :
> >   - compatible : shall contain only one of the following:
> > -                       "qcom,sdm845-rsc-hlos"
> > +                       "qcom,sdm845-aggre1_noc",
> > +                       "qcom,sdm845-aggre2_noc",
> > +                       "qcom,sdm845-config_noc",
> > +                       "qcom,sdm845-dc_noc",
> > +                       "qcom,sdm845-gladiator_noc",
> > +                       "qcom,sdm845-mem_noc",
> > +                       "qcom,sdm845-mmss_noc",
> > +                       "qcom,sdm845-system_noc",
> >   - #interconnect-cells : should contain 1
> > +- reg : shall contain base register location and length
> > +- qcom,bcm-voter : shall contain phandles to bcm voters
> >   
> >   Examples:
> >   
> > -apps_rsc: rsc {
> > -       rsc_hlos: interconnect {
> > -               compatible = "qcom,sdm845-rsc-hlos";
> > -               #interconnect-cells = <1>;
> > -       };
> > +aggre1_noc: interconnect@16e0000 {
> > +       compatible = "qcom,sdm845-aggre1_noc";
> > +       reg = <0x16e0000 0xd080>;
> > +       interconnect-cells = <1>;
> > +       qcom,bcm-voter = <&apps_bcm_voter>;
> >   };
> >   
> > +mmss_noc: interconnect@1740000 {
> > +       compatible = "qcom,sdm845-mmss_noc";
> > +       reg = <0x1740000 0x1c1000>;
> > +       interconnect-cells = <1>;
> > +       qcom,bcm-voter = <&apps_bcm_voter>, <&disp_bcm_voter>;
> > +};
> > +
> > +mem_noc: interconnect@1380000 {
> > +       compatible = "qcom,sdm845-mem_noc";
> > +       reg = <0 0x1380000 0 0x27200>;
> > +       #interconnect-cells = <1>;
> > +       qcom,bcm-voter = <&apps_bcm_voter>, <&disp_bcm_voter>;
> > +};
> How does a consumer target a particular RSC? For example, how can
> display decide to use the disp_bcm_voter node from mem_noc here? Maybe
> you can add that consumer to the example?

I was thinking that the association between the bcm voters and the icc 
nodes would be handled by the interconnect provider, and that there 
would be a set of display specific icc nodes with their own unique IDs 
that the consumers could reference. I will mention this as part of the 
description and provide an example.

Ex: interconnects = <&mmss_noc MASTER_MDP0_DISP &mem_noc SLAVE_EBI_DISP>;

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