linux-kernel - Re: [PATCH v8 04/13] arm64/acpi: Create arch specific cpu to acpi id helper

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Message-ID: <a00dd78c-6e94-26a2-1515-c677a032e6ce@arm.com>
Date:   Fri, 27 Apr 2018 14:08:14 +0100
From:   Sudeep Holla <sudeep.holla@....com>
To:     Jeremy Linton <jeremy.linton@....com>, linux-acpi@...r.kernel.org
Cc:     Sudeep Holla <sudeep.holla@....com>,
        linux-arm-kernel@...ts.infradead.org, Lorenzo.Pieralisi@....com,
        hanjun.guo@...aro.org, rjw@...ysocki.net, Will.Deacon@....com,
        Catalin.Marinas@....com, gregkh@...uxfoundation.org,
        Mark.Rutland@....com, linux-kernel@...r.kernel.org,
        linux-riscv@...ts.infradead.org, wangxiongfeng2@...wei.com,
        vkilari@...eaurora.org, ahs3@...hat.com, Dietmar.Eggemann@....com,
        Morten.Rasmussen@....com, palmer@...ive.com, lenb@...nel.org,
        john.garry@...wei.com, austinwc@...eaurora.org,
        tnowicki@...iumnetworks.com, jhugo@....qualcomm.com,
        timur@....qualcomm.com, ard.biesheuvel@...aro.org
Subject: Re: [PATCH v8 04/13] arm64/acpi: Create arch specific cpu to acpi id
 helper



On 26/04/18 19:33, Jeremy Linton wrote:
> Hi,
> 
> On 04/26/2018 05:27 AM, Sudeep Holla wrote:
>>
>>
>> On 26/04/18 00:31, Jeremy Linton wrote:
>>> Its helpful to be able to lookup the acpi_processor_id associated
>>> with a logical cpu. Provide an arm64 helper to do this.
>>>
>>
>> As I pointed out in the earlier version, this patch is not required.
>> The acpi_id stored in the acpi_processor can be used for this.
>> Won't the below change make it work ? I can't think of any reason why it
>> shouldn't.
> 
> So, I only noticed your previous email last night on the mail archive,
> as I was applying your review/ack tags and couldn't find a response for
> this patch, seem the spam/etc filters need some further tweaking!
>

Ah that's bad.

> At that point, I was pretty sure the suggestion wasn't going to work out
> of the box as a lot of this code is running fairly early in the boot
> process. I spent a bit of time and plugged the change in to verify that
> assertion, and yes the per_cpu processor/acpi bits aren't setup early
> enough to be used by much of this code. It is being called from
> init_cpu_topology()/smp_prepare_cpus() which precedes
> do_basic_setup/do_initcalls() which is what runs the acpi_init()
> sequence which ends up eventually allocating the required data
> structures. So without restructuring the core boot sequence, this seems
> like a reasonable solution.
> 

OK makes sense. I completely ignored topology related patches as I
haven't looked at them yet and assumed cacheinfo is the only user. Sorry
for that.

-- 
Regards,
Sudeep