[PATCH v5 2/4] Documentation: arm64/arm: dt bindings for numa.

[Ganapatrao Kulkarni]

On Tue, Oct 13, 2015 at 10:17 PM, Mark Rutland <mark.rutland at arm.com> wrote:
>> > Hi Mark,
>> >
>> > i am thinking, if we could not address(or becomes complex)  these topologies
>> > using associativity,
>> > we should think of an alternate binding which suits existing and upcoming
>> > arm64 platforms.
>> > can we think of below numa binding which is inline with ACPI and will
>> > address all sort of topologies!
>> >
>> > i am proposing as below,
>> >
>> > 1. introduce "proximity" node property. this property will be
>> > present in dt nodes like memory, cpu, bus and devices(like associativity
>> > property) and
>> > will tell which numa node(proximity domain) this dt node belongs to.
>> >
>> > examples:
>> >                cpu at 000 {
>> >                         device_type = "cpu";
>> >                         compatible = "cavium,thunder", "arm,armv8";
>> >                         reg = <0x0 0x000>;
>> >                         enable-method = "psci";
>> >                         proximity = <0>;
>> >                 };
>> >                cpu at 001 {
>> >                         device_type = "cpu";
>> >                         compatible = "cavium,thunder", "arm,armv8";
>> >                         reg = <0x0 0x001>;
>> >                         enable-method = "psci";
>> >                         proximity = <1>;
>> >                 };
>> >
>> >        memory at 00000000 {
>> >                 device_type = "memory";
>> >                 reg = <0x0 0x01400000 0x3 0xFEC00000>;
>> >                 proximity =<0>;
>> >
>> >         };
>> >
>> >         memory at 10000000000 {
>> >                 device_type = "memory";
>> >                 reg = <0x100 0x00400000 0x3 0xFFC00000>;
>> >                 proximity =<1>;
>> >         };
>> >
>> > pcie0 at 0x8480,00000000 {
>> >                 compatible = "cavium,thunder-pcie";
>> >                 device_type = "pci";
>> >                 msi-parent = <&its>;
>> >                 bus-range = <0 255>;
>> >                 #size-cells = <2>;
>> >                 #address-cells = <3>;
>> >                 #stream-id-cells = <1>;
>> >                 reg = <0x8480 0x00000000 0 0x10000000>;  /*Configuration
>> > space */
>> >                 ranges = <0x03000000 0x8010 0x00000000 0x8010 0x00000000
>> > 0x70 0x00000000>, /* mem ranges */
>> >                          <0x03000000 0x8300 0x00000000 0x8300 0x00000000
>> > 0x500 0x00000000>;
>> >                proximity =<0>;
>> >         };
>> >
>> >
>> > 2. Introduce new dt node "proximity-map" which will capture the NxN numa
>> > node distance matrix.
>> >
>> > for example,  4 nodes connected in mesh/ring structure as,
>> > A(0) <connected to> B(1) <connected to> C(2) <connected to> D(3) <connected
>> > to> A(1)
>> >
>> > relative distance would be,
>> >       A -> B = 20
>> >       B -> C  = 20
>> >       C -> D = 20
>> >       D -> A = 20
>> >       A -> C = 40
>> >       B -> D = 40
>> >
>> > and dt presentation for this distance matrix is :
>> >
>> >        proximity-map {
>> >              node-count = <4>;
>> >              distance-matrix = <0 0  10>,
>> >                                 <0 1  20>,
>> >                                 <0 2  40>,
>> >                                 <0 3  20>,
>> >                                 <1 0  20>,
>> >                                 <1 1  10>,
>> >                                 <1 2  20>,
>> >                                 <1 3  40>,
>> >                                 <2 0  40>,
>> >                                 <2 1  20>,
>> >                                 <2 2  10>,
>> >                                 <2 3  20>,
>> >                                 <3 0  20>,
>> >                                 <3 1  40>,
>> >                                 <3 2  20>,
>> >                                 <3 3  10>;
>> >           }
>> >
>> > the entries like < 0 0 > < 1 1>  < 2 2> < 3 3> can be optional and code can
>> > put default value(local distance).
>> > the entries like <1 0> can be optional if <0 1> and <1 0> are of same
>> > distance.
>> is this binding looks ok?
>
> This looks roughly requivalent to the ACPI SLIT, which means it's as
> powerful, which allays my previous concerns.
>
>> i can implement this and submit in next version of patchset.
>
> Please put together (plaintext) patches.
>
> Then we have a sensible baseline that we can work from; it's somewhat
> difficult for others to join the disacussion here as-is.
thanks, will post the v6 in couple of days with implementation based
on this binding proposal..
>
> Thanks,
> Mark.

thanks
Ganapat