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Subject: Re: [PATCH v6 0/7] Unify CPU topology across ARM & RISC-V
To:     Atish Patra <atish.patra@wdc.com>, linux-kernel@vger.kernel.org
Cc:     Albert Ou <aou@eecs.berkeley.edu>,
        Anup Patel <anup@brainfault.org>,
        Catalin Marinas <catalin.marinas@arm.com>,
        "David S. Miller" <davem@davemloft.net>,
        devicetree@vger.kernel.org,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Ingo Molnar <mingo@kernel.org>,
        Linus Walleij <linus.walleij@linaro.org>,
        linux-riscv@lists.infradead.org,
        Mark Rutland <mark.rutland@arm.com>,
        Mauro Carvalho Chehab <mchehab+samsung@kernel.org>,
        Morten Rasmussen <morten.rasmussen@arm.com>,
        Otto Sabart <ottosabart@seberm.com>,
        Palmer Dabbelt <palmer@sifive.com>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        "Peter Zijlstra (Intel)" <peterz@infradead.org>,
        "Rafael J. Wysocki" <rafael@kernel.org>,
        Rob Herring <robh+dt@kernel.org>,
        Sudeep Holla <sudeep.holla@arm.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Will Deacon <will.deacon@arm.com>,
        Russell King <linux@armlinux.org.uk>,
        linux-arm-kernel@lists.infradead.org
References: <20190529211340.17087-1-atish.patra@wdc.com>
From:   Jeremy Linton <jeremy.linton@arm.com>
Message-ID: <1b61e699-79c7-bbfd-c7ed-d51d321ae7ef@arm.com>
Date:   Thu, 30 May 2019 16:12:18 -0500
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Hi,

On 5/29/19 4:13 PM, Atish Patra wrote:
> The cpu-map DT entry in ARM can describe the CPU topology in much better
> way compared to other existing approaches. RISC-V can easily adopt this
> binding to represent its own CPU topology. Thus, both cpu-map DT
> binding and topology parsing code can be moved to a common location so
> that RISC-V or any other architecture can leverage that.
> 
> The relevant discussion regarding unifying cpu topology can be found in
> [1].
> 
> arch_topology seems to be a perfect place to move the common code. I
> have not introduced any significant functional changes in the moved code.
> The only downside in this approach is that the capacity code will be
> executed for RISC-V as well. But, it will exit immediately after not
> able to find the appropriate DT node. If the overhead is considered too
> much, we can always compile out capacity related functions under a
> different config for the architectures that do not support them.
> 
> There was an opportunity to unify topology data structure for ARM32 done
> by patch 3/4. But, I refrained from making any other changes as I am not
> very well versed with original intention for some functions that
> are present in arch_topology.c. I hope this patch series can be served
> as a baseline for such changes in the future.
> 
> The patches have been tested for RISC-V and compile tested for ARM64,
> ARM32 & x86.
>

I applied these to 5.2rc2, along with my PPTT/MT change and verified the 
system & scheduler topology/etc on DAWN and ThunderX2 using ACPI on 
arm64. They appear to be working correctly.

so for the series,
Tested-by: Jeremy Linton <jeremy.linton@arm.com>

The code itself looks fine to me as well:

Reviewed-by: Jeremy Linton <jeremy.linton@arm.com>

Thanks!

> The socket change[2] is also now part of this series.
> 
> [1] https://lkml.org/lkml/2018/11/6/19
> [2] https://lkml.org/lkml/2018/11/7/918
> 
> QEMU changes for RISC-V topology are available at
> 
> https://github.com/atishp04/qemu/tree/riscv_topology_dt
> 
> HiFive Unleashed DT with topology node is available here.
> https://github.com/atishp04/opensbi/tree/HiFive_unleashed_topology
> 
> It can be verified with OpenSBI with following additional compile time
> option.
> 
> FW_PAYLOAD_FDT="unleashed_topology.dtb"
> 
> Changes from v5->v6
> 1. Added two more patches from Sudeep about maintainership of arch_topology.c
>     and Kconfig update.
> 2. Added Tested-by & Reviewed-by
> 3. Fixed a nit (reordering of variables)
> 
> Changes from v4-v5
> 1. Removed the arch_topology.h header inclusion from topology.c and arch_topology.c
> file. Added it in linux/topology.h.
> 2. core_id is set to -1 upon reset. Otherwise, ARM topology store function does not
> work.
> 
> Changes from v3->v4
> 1. Get rid of ARM32 specific information in topology structure.
> 2. Remove redundant functions from ARM32 and use common code instead.
> 
> Changes from v2->v3
> 1. Cover letter update with experiment DT for topology changes.
> 2. Added the patch for [2].
> 
> Changes from v1->v2
> 1. ARM32 can now use the common code as well.
> 
> Atish Patra (4):
> dt-binding: cpu-topology: Move cpu-map to a common binding.
> cpu-topology: Move cpu topology code to common code.
> arm: Use common cpu_topology structure and functions.
> RISC-V: Parse cpu topology during boot.
> 
> Sudeep Holla (3):
> Documentation: DT: arm: add support for sockets defining package
> boundaries
> base: arch_topology: update Kconfig help description
> MAINTAINERS: Add an entry for generic architecture topology
> 
> .../topology.txt => cpu/cpu-topology.txt}     | 134 ++++++--
> MAINTAINERS                                   |   7 +
> arch/arm/include/asm/topology.h               |  20 --
> arch/arm/kernel/topology.c                    |  60 +---
> arch/arm64/include/asm/topology.h             |  23 --
> arch/arm64/kernel/topology.c                  | 303 +-----------------
> arch/riscv/Kconfig                            |   1 +
> arch/riscv/kernel/smpboot.c                   |   3 +
> drivers/base/Kconfig                          |   2 +-
> drivers/base/arch_topology.c                  | 298 +++++++++++++++++
> include/linux/arch_topology.h                 |  26 ++
> include/linux/topology.h                      |   1 +
> 12 files changed, 452 insertions(+), 426 deletions(-)
> rename Documentation/devicetree/bindings/{arm/topology.txt => cpu/cpu-topology.txt} (66%)
> 
> --
> 2.21.0
>