linux-kernel - Re: [PATCH] ACPI/PPTT: use ACPI ID whenever ACPI_PPTT_ACPI_PROCESSOR_ID

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Message-ID: <3895a0d8-9cca-2512-a06e-0ee2ac7db773@arm.com>
Date:   Mon, 2 Jul 2018 10:57:47 +0100
From:   Sudeep Holla <sudeep.holla@....com>
To:     "Rafael J. Wysocki" <rafael@...nel.org>
Cc:     Sudeep Holla <sudeep.holla@....com>,
        ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        Jeremy Linton <jeremy.linton@....com>,
        shunyong.yang@...-semitech.com, yu.zheng@...-semitech.com,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Andrew Jones <drjones@...hat.com>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>
Subject: Re: [PATCH] ACPI/PPTT: use ACPI ID whenever
 ACPI_PPTT_ACPI_PROCESSOR_ID_VALID is set



On 02/07/18 10:06, Rafael J. Wysocki wrote:
> On Fri, Jun 29, 2018 at 6:17 PM, Sudeep Holla <sudeep.holla@....com> wrote:
>> Currently we use the ACPI processor ID only for the leaf/processor nodes
>> as the specification states it must match the value of ACPI processor ID
>> field in the processor’s entry in the MADT.
>>
>> However, if a PPTT structure represents processors group, it match a
>> processor container UID in the namespace and ACPI_PPTT_ACPI_PROCESSOR_ID_VALID
>> flag describe whether the ACPI processor ID is valid.
>>
>> Lets use UID whenever ACPI_PPTT_ACPI_PROCESSOR_ID_VALID is set to be
>> consistent instead of using table offset as it's currently done for non
>> leaf nodes.
>>
>> Cc: "Rafael J. Wysocki" <rjw@...ysocki.net>
>> Signed-off-by: Sudeep Holla <sudeep.holla@....com>
>> ---
>>  drivers/acpi/pptt.c | 10 ++++++++--
>>  1 file changed, 8 insertions(+), 2 deletions(-)
>>
>> Hi,
>>
>> There's ongoing discussion on assigning ID based in OS using simple
>> counters. It can never be consistent with firmware's view. So if the
>> firmware provides valid UID for non-processors node, we must use it.
> 
> OK
> 
> Do you regard this as a fix for the recently merged PPTT material?  If
> so, I should apply it as a fix for 4.18.
> 

Yes, it should be considered as fix IMO.

-- 
Regards,
Sudeep