Re: [PATCH] cxl: core/region - ignore interleave granularity when ways=1

[Gregory Price]

On Wed, Apr 02, 2025 at 02:59:17PM -0700, Dan Williams wrote:
> Gregory Price wrote:
> > When validating decoder IW/IG when setting up regions, the granularity
> > is irrelevant when iw=1 - all accesses will always route to the only
> > target anyway - so all ig values are "correct". Loosen the requirement
> > that `ig = (parent_iw * parent_ig)` when iw=1.
> 
> Can you say a bit more here about the real world impact like we chatted
> about on Discord? Something like:
> 
> ---
> The platform BIOS on "platform-X" specifies a 512-byte
> interleave-granularity CXL Window when 256-byte is expected. This leads
> to Linux erroneously rejecting the region configuration of 2 devices
> attached to an x1 host bridge.
> ---
> 
> That way distros and platform-X folks can flag the importance of this fix.

Would like this inline or just in the changelog?

~Gregory