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From:   Dan Williams <dan.j.williams@intel.com>
Date:   Tue, 19 Jun 2018 16:46:27 -0700
Message-ID: <CAPcyv4iqb52RiCnCntaSFr1vVOa9A7PZ7=Ob2StYMq-OSmo7DQ@mail.gmail.com>
Subject: Re: [PATCH v3 1/2] acpi/nfit: Update nfit driver to comply with ACPI 6.1
To:     "Elliott, Robert (Persistent Memory)" <elliott@hpe.com>
Cc:     "Kani, Toshi" <toshi.kani@hpe.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-nvdimm@lists.01.org" <linux-nvdimm@lists.01.org>,
        "Moore, Robert" <robert.moore@intel.com>,
        "Li, Juston" <juston.li@intel.com>,
        "rjw@rjwysocki.net" <rjw@rjwysocki.net>,
        "linux-acpi@vger.kernel.org" <linux-acpi@vger.kernel.org>
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On Tue, Jun 19, 2018 at 12:53 PM, Elliott, Robert (Persistent Memory)
<elliott@hpe.com> wrote:
>
>
>> -----Original Message-----
>> From: linux-kernel-owner@vger.kernel.org [mailto:linux-kernel-
>> owner@vger.kernel.org] On Behalf Of Dan Williams
>> Sent: Tuesday, June 19, 2018 10:29 AM
>> Subject: Re: [PATCH v3 1/2] acpi/nfit: Update nfit driver to comply with
>> ACPI 6.1
> ...
>> >
>> > Here are some examples (kernel 4.17):
>
> Note that these values were as reported on a little-endian system.
>
>> Ok, so the lowest significant byte of the Micron id is supposed to be
>> 0x2c and this text representation matches that. So the bytes are being
>> endian swapped when written to the SPD?
>
> SPD byte 320 is 0x80. That's the bank number byte (with odd parity).
> SPD byte 321 is 0x2c. That's the manufacturer code byte (with odd parity).
>
> If treated as a single 2-byte value, that is:
> * 0x802c (32812 in decimal) if interpreted as big-endian
> * 0x2c80 (11392 in decimal) if interpreted as little-endian

Ok, JEDEC defines byte 320 as the LSB, so the fact that Linux is
showing 0x2c as the LSB is wrong. Linux needs to be fixed.