linux-kernel - Re: [PATCH 3/3] cxl/mem: Demarcate vendor specific capability IDs

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Date:   Wed, 19 May 2021 13:01:00 -0700
From:   Dan Williams <dan.j.williams@...el.com>
To:     Ben Widawsky <ben.widawsky@...el.com>
Cc:     linux-cxl@...r.kernel.org, Linux PCI <linux-pci@...r.kernel.org>,
        Linux ACPI <linux-acpi@...r.kernel.org>,
        "Weiny, Ira" <ira.weiny@...el.com>,
        Vishal L Verma <vishal.l.verma@...el.com>,
        "Schofield, Alison" <alison.schofield@...el.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 3/3] cxl/mem: Demarcate vendor specific capability IDs

On Thu, Apr 15, 2021 at 4:27 PM Ben Widawsky <ben.widawsky@...el.com> wrote:
>
> Vendor capabilities occupy 0x8000 to 0xFFFF according to CXL 2.0 spec
> 8.2.8.2.1 CXL Device Capabilities. While they are not defined by the
> spec, they are allowed and not "unknown". Call this detail out in the
> logs to let users easily distinguish the difference.
>
> v2: Should be greater than or equal to (Ben)
>
> Fixes: 8adaf747c9f0b ("cxl/mem: Find device capabilities")
> Signed-off-by: Ben Widawsky <ben.widawsky@...el.com>
> ---
>  drivers/cxl/mem.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/cxl/mem.c b/drivers/cxl/mem.c
> index c05617b0ba4b..28c7c29567b3 100644
> --- a/drivers/cxl/mem.c
> +++ b/drivers/cxl/mem.c
> @@ -939,7 +939,10 @@ static int cxl_mem_setup_regs(struct cxl_mem *cxlm)
>                         cxlm->memdev_regs = register_block;
>                         break;
>                 default:
> -                       dev_dbg(dev, "Unknown cap ID: %x (0x%x)\n", cap_id, offset);
> +                       if (cap_id >= 0x8000)
> +                               dev_dbg(dev, "Vendor cap ID: %x (0x%x)\n", cap_id, offset);
> +                       else
> +                               dev_dbg(dev, "Unknown cap ID: %x (0x%x)\n", cap_id, offset);

This wants the same %#x fixup that Vishal noted on patch2 [1], and I
think it would be useful to clarify that the second number is indeed
an offset: "Unknown cap_id: %#x offset: %#x\n"

[1]: http://lore.kernel.org/r/40063fe52fcaa066a42d352b13128b6762277542.camel@intel.com