linux-kernel - Re: [PATCH v2 1/2] arm64: topology: move store_cpu

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Message-ID: <24e3d8a0-c998-4a68-af28-57dcf15682ee@microchip.com>
Date:   Mon, 11 Jul 2022 10:24:38 +0000
From:   <Conor.Dooley@...rochip.com>
To:     <sudeep.holla@....com>, <Conor.Dooley@...rochip.com>
CC:     <paul.walmsley@...ive.com>, <palmer@...belt.com>,
        <palmer@...osinc.com>, <aou@...s.berkeley.edu>,
        <catalin.marinas@....com>, <will@...nel.org>,
        <gregkh@...uxfoundation.org>, <rafael@...nel.org>,
        <linux@...linux.org.uk>, <arnd@...db.de>,
        <Daire.McNamara@...rochip.com>, <niklas.cassel@....com>,
        <damien.lemoal@...nsource.wdc.com>, <geert@...ux-m68k.org>,
        <zong.li@...ive.com>, <kernel@...il.dk>, <hahnjo@...njo.de>,
        <guoren@...nel.org>, <anup@...infault.org>,
        <atishp@...shpatra.org>, <heiko@...ech.de>,
        <philipp.tomsich@...ll.eu>, <robh@...nel.org>, <maz@...nel.org>,
        <viresh.kumar@...aro.org>, <linux-riscv@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>, <Brice.Goglin@...ia.fr>
Subject: Re: [PATCH v2 1/2] arm64: topology: move store_cpu_topology() to
 shared code



On 11/07/2022 11:02, Sudeep Holla wrote:
> On Sat, Jul 09, 2022 at 12:58:57PM +0000, Conor.Dooley@...rochip.com wrote:
>> Looking at the arm32 implementation - it appears to be mostly the sort of MPIDR
>> stuff that was removed from the arm64 implementation in 3102bc0e6ac7 ("arm64:
>> topology: Stop using MPIDR for topology information"). Could arm32 benefit from
>> the same shared implemenation too, or is usage of MPIDR only invalid for arm64?
> 
> I don't recall all the details but IIRC there are parts if arch_topology
> that are ARM64/RISC-V only. ARM32 doesn't use it as it may break old
> platforms. Some of the functions that still arm32 specific are retained
> in arch/arm
> 
>> The other difference is a call to update_cpu_capacity() in the arm32
>> implementation. Could that be moved to smp_store_cpu_info() which is the only
>> callsite of store_cpu_topology()?
>>
> 
> No please, leave arm32 as is. It was done for a reason like that and it
> help to not break some of the old 32-by platforms.

Thought that might be the case, I won't (and didn't) touch arm32!

Thanks,
Conor.