Re: [PATCH v4 7/9] cxl/region: Factor out cxl_port_setup_decoder()

[Jonathan Cameron <jic23@kernel.org>]

On Sat, 17 Oct 2026 12:28:53 -0700
Alison Schofield <alison.schofield@intel.com> wrote:

> Once cxl_switch_port_setup_targets() has calculated the interleave for a
> port's decoder, it either checks that interleave against the decoder
> settings found for an auto region, or checks the decoder's interleave
> capabilities and programs the decoder for a user created region. Both paths
> are open coded in cxl_switch_port_setup_targets().
> 
> Move both paths to a new helper, cxl_port_setup_decoder().
> 
> No functional change.
> 
> Signed-off-by: Alison Schofield <alison.schofield@intel.com>
> Reviewed-by: Dave Jiang <dave.jiang@intel.com>
> Reviewed-by: Li Ming <ming.li@zohomail.com>
Reviewed-by: Jonathan Cameron <jonathan.cameron@oss.qualcomm.com>

given my feedback on v3 is now in the next patch.

> ---
>  drivers/cxl/core/region.c | 88 ++++++++++++++++++++++-----------------
>  1 file changed, 50 insertions(+), 38 deletions(-)
> 
> diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
> index d25df041e922..025cf21adfa9 100644
> --- a/drivers/cxl/core/region.c
> +++ b/drivers/cxl/core/region.c
> @@ -1565,46 +1565,11 @@ static int cxl_port_calc_interleave(struct cxl_port *port, struct cxl_region *cx
>  	return 0;
>  }
>  
> -static int cxl_switch_port_setup_targets(struct cxl_switch_decoder *cxlsd,
> -					 struct cxl_region *cxlr,
> -					 struct cxl_endpoint_decoder *cxled)
> +static int cxl_port_setup_decoder(struct cxl_port *port, struct cxl_region *cxlr,
> +				  struct cxl_decoder *cxld, int iw, int ig)
>  {
> -	struct cxl_port *port = to_cxl_port(cxlsd->cxld.dev.parent);
> -	int iw, ig, rc, pos = cxled->pos;
> -	struct cxl_region_ref *cxl_rr = cxl_rr_load(port, cxlr);
> -	struct cxl_memdev *cxlmd = cxled_to_memdev(cxled);
> -	struct cxl_ep *ep = cxl_ep_load(port, cxlmd);
>  	struct cxl_region_params *p = &cxlr->params;
> -	struct cxl_decoder *cxld = &cxlsd->cxld;
> -
> -	/*
> -	 * While root level decoders support x3, x6, x12, switch level
> -	 * decoders only support powers of 2 up to x16.
> -	 */
> -	if (!is_power_of_2(cxl_rr->nr_targets)) {
> -		dev_dbg(&cxlr->dev, "%s:%s: invalid target count %d\n",
> -			dev_name(port->uport_dev), dev_name(&port->dev),
> -			cxl_rr->nr_targets);
> -		return -EINVAL;
> -	}
> -
> -	if (cxl_rr->nr_targets_set) {
> -		for (int i = 0; i < cxl_rr->nr_targets_set; i++)
> -			if (ep->dport == cxlsd->target[i]) {
> -				int distance = cxl_port_peer_distance(port, cxlr);
> -
> -				rc = check_last_peer(cxled, ep, cxl_rr,
> -						     distance);
> -				if (rc)
> -					return rc;
> -				goto out_target_set;
> -			}
> -		goto add_target;
> -	}
> -
> -	rc = cxl_port_calc_interleave(port, cxlr, cxl_rr, &iw, &ig);
> -	if (rc)
> -		return rc;
> +	int rc;
>  
>  	if (test_bit(CXL_REGION_F_AUTO, &cxlr->flags)) {
>  		if (cxld->interleave_ways != iw ||
> @@ -1643,6 +1608,53 @@ static int cxl_switch_port_setup_targets(struct cxl_switch_decoder *cxlsd,
>  	}
>  	dev_dbg(&cxlr->dev, "%s:%s iw: %d ig: %d\n", dev_name(port->uport_dev),
>  		dev_name(&port->dev), iw, ig);
> +
> +	return 0;
> +}
> +
> +static int cxl_switch_port_setup_targets(struct cxl_switch_decoder *cxlsd,
> +					 struct cxl_region *cxlr,
> +					 struct cxl_endpoint_decoder *cxled)
> +{
> +	struct cxl_port *port = to_cxl_port(cxlsd->cxld.dev.parent);
> +	int iw, ig, rc, pos = cxled->pos;
> +	struct cxl_region_ref *cxl_rr = cxl_rr_load(port, cxlr);
> +	struct cxl_memdev *cxlmd = cxled_to_memdev(cxled);
> +	struct cxl_ep *ep = cxl_ep_load(port, cxlmd);
> +	struct cxl_decoder *cxld = &cxlsd->cxld;
> +
> +	/*
> +	 * While root level decoders support x3, x6, x12, switch level
> +	 * decoders only support powers of 2 up to x16.
> +	 */
> +	if (!is_power_of_2(cxl_rr->nr_targets)) {
> +		dev_dbg(&cxlr->dev, "%s:%s: invalid target count %d\n",
> +			dev_name(port->uport_dev), dev_name(&port->dev),
> +			cxl_rr->nr_targets);
> +		return -EINVAL;
> +	}
> +
> +	if (cxl_rr->nr_targets_set) {
> +		for (int i = 0; i < cxl_rr->nr_targets_set; i++)
> +			if (ep->dport == cxlsd->target[i]) {
> +				int distance = cxl_port_peer_distance(port, cxlr);
> +
> +				rc = check_last_peer(cxled, ep, cxl_rr,
> +						     distance);
> +				if (rc)
> +					return rc;
> +				goto out_target_set;
> +			}
> +		goto add_target;
> +	}
> +
> +	rc = cxl_port_calc_interleave(port, cxlr, cxl_rr, &iw, &ig);
> +	if (rc)
> +		return rc;
> +
> +	rc = cxl_port_setup_decoder(port, cxlr, cxld, iw, ig);
> +	if (rc)
> +		return rc;
>  add_target:
>  	if (cxl_rr->nr_targets_set == cxl_rr->nr_targets) {
>  		dev_dbg(&cxlr->dev,