Re: [RFC PATCH v2 3/4] arm64:thunder: Add initial dts for Cavium's Thunder SoC in 2 Node topology.

[Roy Franz <roy.franz-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>]

On Mon, Nov 24, 2014 at 6:59 AM, Arnd Bergmann <arnd-r2nGTMty4D4@public.gmane.org> wrote:
> On Saturday 22 November 2014 02:53:29 Ganapatrao Kulkarni wrote:
>> +/ {
>> +     model = "Cavium ThunderX CN88XX board";
>> +     compatible = "cavium,thunder-88xx";
>
> No wildcards in compatible strings or model names please. List the
> exact chip that you are using.
>
>> +     aliases {
>> +             serial0 = &uaa0;
>> +             serial1 = &uaa1;
>> +     };
>> +
>> +     memory@00c00000 {
>> +             device_type = "memory";
>> +             reg = <0x0 0x00000000 0x0 0x80000000>;
>> +     };
>> +
>> +     memory@10000000000 {
>> +             device_type = "memory";
>> +             reg = <0x100 0x00000000 0x0 0x80000000>;
>> +     };
>> +
>> +     numa-map {
>> +             #address-cells = <2>;
>> +             #size-cells = <1>;
>> +             #node-count = <2>;
>> +             mem-map = <0x0 0x00000000 0>,
>> +                        <0x100 0x00000000 1>;
>> +
>> +               cpu-map = <0 47 0>,
>> +                     <48 95 1>;
>> +
>> +             node-matrix=    <0 0 10>,
>> +                             <0 1 20>,
>> +                             <1 0 20>,
>> +                             <1 1 10>;
>
> I don't know how much history is behind this binding. Have you looked
> at the sPAPR way of doing this? I don't remember exactly how that is
> done, but we'd need a good reason to discard that and implement
> something else for arm64.
>
> If we create a new binding, I don't think the 'numa-map' node you
> have here is the best solution. We already have device nodes for each
> memory segment and each CPU in the system. Why not work with those
> nodes directly?

The DT memory nodes don't exist in an EFI system, as the EFI memory
map is used instead.
Using EFI as the boot firmware doesn't require the use of ACPI for
hardware description,
so the EFI/DT case is one that we should support.

>> +
>> +     timer {
>> +             compatible = "arm,armv8-timer";
>> +             interrupts = <1 13 0xff01>,
>> +                          <1 14 0xff01>,
>> +                          <1 11 0xff01>,
>> +                          <1 10 0xff01>;
>> +     };
>> +
>> +     soc {
>> +             compatible = "simple-bus";
>> +             #address-cells = <2>;
>> +             #size-cells = <2>;
>> +             ranges;
>> +
>> +             refclk50mhz: refclk50mhz {
>> +                     compatible = "fixed-clock";
>> +                     #clock-cells = <0>;
>> +                     clock-frequency = <50000000>;
>> +                     clock-output-names = "refclk50mhz";
>> +             };
>
> Why is the timer outside of the soc and the refclk is inside?
> I would have expected the opposite.
>
>         Arnd
>
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