linux-kernel - Re: [PATCH] ACPI/HMAT: Fix the parsing of Cache Associativity and Write Policy

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Date:   Mon, 9 Dec 2019 11:01:42 +0100
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Tao Xu <tao3.xu@...el.com>
Cc:     Rafael Wysocki <rafael.j.wysocki@...el.com>,
        Len Brown <lenb@...nel.org>,
        Keith Busch <keith.busch@...el.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Dan Williams <dan.j.williams@...el.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] ACPI/HMAT: Fix the parsing of Cache Associativity and
 Write Policy

On Mon, Dec 2, 2019 at 8:03 AM Tao Xu <tao3.xu@...el.com> wrote:
>
> In chapter 5.2.27.5, Table 5-147: Field "Cache Attributes" of
> ACPI 6.3 spec: 0 is "None", 1 is "Direct Mapped", 2 is "Complex Cache
> Indexing" for Cache Associativity; 0 is "None", 1 is "Write Back",
> 2 is "Write Through" for Write Policy.

Well, I'm not sure what the connection between the above statement,
which is correct AFAICS, and the changes made by the patch is.

Is that the *_OTHER symbol names are confusing or something deeper?

> Signed-off-by: Tao Xu <tao3.xu@...el.com>
> ---
>  drivers/acpi/numa/hmat.c | 4 ++--
>  include/linux/node.h     | 4 ++--
>  2 files changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/acpi/numa/hmat.c b/drivers/acpi/numa/hmat.c
> index 2c32cfb72370..719d0279563d 100644
> --- a/drivers/acpi/numa/hmat.c
> +++ b/drivers/acpi/numa/hmat.c
> @@ -383,7 +383,7 @@ static __init int hmat_parse_cache(union acpi_subtable_headers *header,
>                 break;
>         case ACPI_HMAT_CA_NONE:
>         default:
> -               tcache->cache_attrs.indexing = NODE_CACHE_OTHER;
> +               tcache->cache_attrs.indexing = NODE_CACHE_NONE;
>                 break;
>         }
>
> @@ -396,7 +396,7 @@ static __init int hmat_parse_cache(union acpi_subtable_headers *header,
>                 break;
>         case ACPI_HMAT_CP_NONE:
>         default:
> -               tcache->cache_attrs.write_policy = NODE_CACHE_WRITE_OTHER;
> +               tcache->cache_attrs.write_policy = NODE_CACHE_WRITE_NONE;
>                 break;
>         }
>         list_add_tail(&tcache->node, &target->caches);
> diff --git a/include/linux/node.h b/include/linux/node.h
> index 4866f32a02d8..6dbd764d09ce 100644
> --- a/include/linux/node.h
> +++ b/include/linux/node.h
> @@ -36,15 +36,15 @@ struct node_hmem_attrs {
>  };
>
>  enum cache_indexing {
> +       NODE_CACHE_NONE,
>         NODE_CACHE_DIRECT_MAP,
>         NODE_CACHE_INDEXED,
> -       NODE_CACHE_OTHER,
>  };
>
>  enum cache_write_policy {
> +       NODE_CACHE_WRITE_NONE,
>         NODE_CACHE_WRITE_BACK,
>         NODE_CACHE_WRITE_THROUGH,
> -       NODE_CACHE_WRITE_OTHER,
>  };
>
>  /**