Re: [PATCH v2 23/28] cxl/region: Attach endpoint decoders

[Jonathan Cameron <Jonathan.Cameron@Huawei.com>]

On Thu, 14 Jul 2022 17:02:52 -0700
Dan Williams <dan.j.williams@intel.com> wrote:

> CXL regions (interleave sets) are made up of a set of memory devices
> where each device maps a portion of the interleave with one of its
> decoders (see CXL 2.0 8.2.5.12 CXL HDM Decoder Capability Structure).
> As endpoint decoders are identified by a provisioning tool they can be
> added to a region provided the region interleave properties are set
> (way, granularity, HPA) and DPA has been assigned to the decoder.
> 
> The attach event triggers several validation checks, for example:
> - is the DPA sized appropriately for the region
> - is the decoder reachable via the host-bridges identified by the
>   region's root decoder
> - is the device already active in a different region position slot
> - are there already regions with a higher HPA active on a given port
>   (per CXL 2.0 8.2.5.12.20 Committing Decoder Programming)
> 
> ...and the attach event affords an opportunity to collect data and
> resources relevant to later programming the target lists in switch
> decoders, for example:
> - allocate a decoder at each cxl_port in the decode chain
> - for a given switch port, how many the region's endpoints are hosted
>   through the port
> - how many unique targets (next hops) does a port need to map to reach
>   those endpoints
> 
> The act of reconciling this information and deploying it to the decoder
> configuration is saved for a follow-on patch.
> 
> Co-developed-by: Ben Widawsky <bwidawsk@kernel.org>
> Signed-off-by: Ben Widawsky <bwidawsk@kernel.org>
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
All the review comment resolutions from v1 look good to me.
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Thanks,

Jonathan