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

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Date:   Mon, 2 Jul 2018 11:06:22 +0200
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Sudeep Holla <sudeep.holla@....com>
Cc:     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 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.

Thanks,
Rafael