Re: [PATCH 3/4] cxl: docs/platform/acpi/srat Add generic target documentation

[Gregory Price <gourry@gourry.net>]

On Tue, May 13, 2025 at 05:31:32PM -0700, Dave Jiang wrote:
> Add description in the SRAT document to descript the Generic Port
> Affinity sub-table.
> 
> Signed-off-by: Dave Jiang <dave.jiang@intel.com>

one wording nit

Reviewed-by: Gregory Price <gourry@gourry.net>

> ---
>  .../driver-api/cxl/platform/acpi/srat.rst     | 21 +++++++++++++++++++
>  1 file changed, 21 insertions(+)
> 
> diff --git a/Documentation/driver-api/cxl/platform/acpi/srat.rst b/Documentation/driver-api/cxl/platform/acpi/srat.rst
> index cc7687645de7..500413b96e70 100644
> --- a/Documentation/driver-api/cxl/platform/acpi/srat.rst
> +++ b/Documentation/driver-api/cxl/platform/acpi/srat.rst
> @@ -42,3 +42,24 @@ Example ::
>                 Enabled : 1
>           Hot Pluggable : 1
>            Non-Volatile : 0
> +
> +
> +Generic Port Affinity
> +=====================
> +The Generic Port Affinity subtable provides an association between a proximity
> +domain and a device handle representing a Generic Port such as a CXL host
> +bridge. With the association, latency and bandwidth numbers can be retrieved
> +from the SRAT for the path between CPU(s) (initiator) and the Generic Port.
> +This helps with constructing the performance coordinates for CXL devices that
> +are hot-plugged and not able to be enumerated by the platform firmware.

This is used to construct performance coordinates for hotplugged CXL devices,
which cannot be enumerated at boot by platform firmware.

> +
> +Example ::
> +
> +         Subtable Type : 06 [Generic Port Affinity]
> +                Length : 20               <- 32d, length of table
> +              Reserved : 00
> +    Device Handle Type : 00               <- 0 - ACPI, 1 - PCI
> +      Proximity Domain : 00000001
> +         Device Handle : ACPI0016:01
> +                 Flags : 00000001         <- Bit 0 (Enabled)
> +              Reserved : 00000000
> -- 
> 2.49.0
>