linux-kernel - Re: [PATCH v14 6/8] arm64: dts: Add AMD Pensando Elba SoC support

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Date:   Tue, 30 May 2023 15:03:47 -0700
From:   Brad Larson <blarson@....com>
To:     <geert@...ux-m68k.org>
CC:     <adrian.hunter@...el.com>, <alcooperx@...il.com>,
        <andy.shevchenko@...il.com>, <arnd@...db.de>, <blarson@....com>,
        <brendan.higgins@...ux.dev>, <briannorris@...omium.org>,
        <broonie@...nel.org>, <catalin.marinas@....com>,
        <conor+dt@...nel.org>, <davidgow@...gle.com>,
        <devicetree@...r.kernel.org>, <fancer.lancer@...il.com>,
        <gerg@...ux-m68k.org>, <gsomlo@...il.com>,
        <hal.feng@...rfivetech.com>, <hasegawa-hitomi@...itsu.com>,
        <j.neuschaefer@....net>, <joel@....id.au>, <kernel@...il.dk>,
        <krzk@...nel.org>, <krzysztof.kozlowski+dt@...aro.org>,
        <lee.jones@...aro.org>, <lee@...nel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <linux-mmc@...r.kernel.org>,
        <linux-spi@...r.kernel.org>, <michal.simek@....com>,
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        <walker.chen@...rfivetech.com>, <will@...nel.org>,
        <zhuyinbo@...ngson.cn>
Subject: Re: [PATCH v14 6/8] arm64: dts: Add AMD Pensando Elba SoC support

Hi Geert,

On Wed, May 24, 2023 at 13:52 Geert Uytterhoeven <geert@...ux-m68k.org> wrote:
> On Tue, May 23, 2023 at 9:30â¯PM Brad Larson <blarson@....com> wrote:
>> On 5/16/23 09:54, Michal Simek wrote:
>> > On 5/15/23 20:16, Brad Larson wrote:
>> >> --- /dev/null
>> >> +++ b/arch/arm64/boot/dts/amd/elba-16core.dtsi
>> >> @@ -0,0 +1,197 @@
>> >> +// SPDX-License-Identifier: (GPL-2.0-only or BSD-2-Clause)
>> >> +/*
>> >> + * Copyright 2020-2022 Advanced Micro Devices, Inc.
>> >
>> > 2023 and the same below.
>>
>> I'll update the copyright in the next submit
>
> Did you make any substantial changes in 2023?

Yes, additional properties were added to l2-cache*

>> >> + */
>> >> +
>> >> +/ {
>> >> +    cpus {
>> >> +            #address-cells = <2>;
>> >> +            #size-cells = <0>;
>> >> +
>> >> +            cpu-map {
>> >> +                    cluster0 {
>> >> +                            core0 { cpu = <&cpu0>; };
>> >> +                            core1 { cpu = <&cpu1>; };
>> >> +                            core2 { cpu = <&cpu2>; };
>> >> +                            core3 { cpu = <&cpu3>; };
>> >> +                    };
>> >> +
>> >> +                    cluster1 {
>> >> +                            core0 { cpu = <&cpu4>; };
>> >> +                            core1 { cpu = <&cpu5>; };
>> >> +                            core2 { cpu = <&cpu6>; };
>> >> +                            core3 { cpu = <&cpu7>; };
>> >> +                    };
>> >> +
>> >> +                    cluster2 {
>> >> +                            core0 { cpu = <&cpu8>; };
>> >> +                            core1 { cpu = <&cpu9>; };
>> >> +                            core2 { cpu = <&cpu10>; };
>> >> +                            core3 { cpu = <&cpu11>; };
>> >> +                    };
>> >> +
>> >> +                    cluster3 {
>> >> +                            core0 { cpu = <&cpu12>; };
>> >> +                            core1 { cpu = <&cpu13>; };
>> >> +                            core2 { cpu = <&cpu14>; };
>> >> +                            core3 { cpu = <&cpu15>; };
>> >> +                    };
>> >> +            };
>> >> +
>> >> +            /* CLUSTER 0 */
>> >> +            cpu0: cpu@0 {
>> >> +                    device_type = "cpu";
>> >> +                    compatible = "arm,cortex-a72";
>> >> +                    reg = <0 0x0>;
>> >
>> > Do you really need 2/0 split here. The first cell is 0 anyway.
>>
>> Yes following 64-bit system definition
>
> You mean for the 64-bit main address space?
> The CPU address space under /cpus is unrelated.

Yes, the reg prop for this node is CPU/threads per dt spec.  Checked the history and
the Elba dt was derived from socionext for these nodes and this is how those device
trees are configured along with over a dozen other devices.  I changed to 
address-cells = <1> and dropped the leading zero from all cpu* reg<> and booting
the system I'm observing no change.  Looking in drivers/of I'm not seeing where
cpu*/reg is read and used, any recommendation?

>> >> +++ b/arch/arm64/boot/dts/amd/elba-flash-parts.dtsi
>> >> @@ -0,0 +1,106 @@
>> >> +// SPDX-License-Identifier: (GPL-2.0-only or BSD-2-Clause)
>> >> +/*
>> >> + * Copyright 2020-2022 Advanced Micro Devices, Inc.
>> >> + */
>> >> +
>> >> +&flash0 {
>> 0xf0000>> +     partitions {
>> >> +            compatible = "fixed-partitions";
>> >> +            #address-cells = <1>;
>> >> +            #size-cells = <1>;
>> >> +            partition@0 {
>> >> +                    label = "flash";
>> >> +                    reg = <0x10000 0xfff0000>;
>> >
>> > This doesn't fit with partition@0 above.
>> > Also size is weird.
>>
>> This is intended to not expose sector 0.
>
> The unit address should still match the first reg entry
> => partition@...00.

Changed to this:

                partition@0 {
                        label = "rsvd";
                        reg = <0x0 0x10000>;
                        read-only;
                };

                partition@...00 {
                        label = "flash";
                        reg = <0x10000 0xfff0000>;
                };

Regards,
Brad