Re: [PATCH 1/3] cxl: Add check for result of interleave ways plus granularity combo

[Alison Schofield <alison.schofield@intel.com>]

Dave - Haven't reviewed yet, but wanted to drop this tidbit - 

On Mon, Aug 08, 2022 at 02:06:57PM -0700, Dave Jiang wrote:
> Add a helper function to check the combination of interleave ways and
> interleave granularity together is sane against the interleave mask from
> the HDM decoder. Add the check to cxl_region_attach() to make sure the
> region config is sane. Add the check to cxl_port_setup_targets() to make
> sure the port setup config is also sane.
> 
> Calculation refers to CXL spec v3 8.2.4.19.13 implementation note #3.
> 
> Signed-off-by: Dave Jiang <dave.jiang@intel.com>

snip

> +static inline int cxl_interleave_verify(struct cxl_port *port,
> +					int ways, int granularity)
> +{
> +	struct cxl_hdm *cxlhdm = dev_get_drvdata(&port->dev);
> +	unsigned int addr_mask;
> +	u16 ig;
> +	u8 iw;

s/ig/eig
s/iw/eiw
For consistency, let's use the "e" version of these names to mean
encoded value.  

> +	int rc;
> +
> +	rc = granularity_to_cxl(granularity, &ig);
> +	if (rc)
> +		return rc;
> +
> +	rc = ways_to_cxl(ways, &iw);
> +	if (rc)
> +		return rc;
> +
> +	if (iw == 0)
> +		return 0;
> +
> +	if (iw < CXL_INTERLEAVE_3_WAY)
> +		addr_mask = GENMASK(ig + 8 + iw - 1, ig + 8);
> +	else
> +		addr_mask = GENMASK((ig + iw) / 3 - 1, ig + 8);
> +
> +	if (~cxlhdm->interleave_mask & addr_mask)
> +		return -EINVAL;
> +
> +	return 0;
> +}
> +
>  struct seq_file;
>  struct dentry *cxl_debugfs_create_dir(const char *dir);
>  void cxl_dpa_debug(struct seq_file *file, struct cxl_dev_state *cxlds);
> 
>