Re: [PATCH v5 11/14] cxl/region: Add function to find a port's switch decoder by range

["Fabio M. De Francesco" <fabio.m.de.francesco@linux.intel.com>]

On Monday, April 28, 2025 11:43:14 PM Central European Summer Time Robert Richter wrote:
> Factor out code to find the switch decoder of a port for a specific
> address range. Reuse the code to search a root decoder, create the
> function cxl_port_find_switch_decoder() and rework
> match_root_decoder_by_range() to be usable for switch decoders too.
> 
> Signed-off-by: Robert Richter <rrichter@amd.com>
> Reviewed-by: Gregory Price <gourry@gourry.net>
> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> Reviewed-by: Dave Jiang <dave.jiang@intel.com>
> Tested-by: Gregory Price <gourry@gourry.net>

Reviewed-by: Fabio M. De Francesco <fabio.m.de.francesco@linux.intel.com>

> ---
>  drivers/cxl/core/region.c | 30 ++++++++++++++++++------------
>  1 file changed, 18 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
> index a292d5c4c4a9..ef5408301714 100644
> --- a/drivers/cxl/core/region.c
> +++ b/drivers/cxl/core/region.c
> @@ -3205,33 +3205,39 @@ static int devm_cxl_add_dax_region(struct cxl_region *cxlr)
>  	return rc;
>  }
>  
> -static int match_root_decoder_by_range(struct device *dev,
> -				       const void *data)
> +static int match_decoder_by_range(struct device *dev, const void *data)
>  {
>  	const struct range *r1, *r2 = data;
> -	struct cxl_root_decoder *cxlrd;
> +	struct cxl_decoder *cxld;
>  
> -	if (!is_root_decoder(dev))
> +	if (!is_switch_decoder(dev))
>  		return 0;
>  
> -	cxlrd = to_cxl_root_decoder(dev);
> -	r1 = &cxlrd->cxlsd.cxld.hpa_range;
> +	cxld = to_cxl_decoder(dev);
> +	r1 = &cxld->hpa_range;
>  	return range_contains(r1, r2);
>  }
>  
> +static struct cxl_decoder *
> +cxl_port_find_switch_decoder(struct cxl_port *port, struct range *hpa)
> +{
> +	struct device *cxld_dev = device_find_child(&port->dev, hpa,
> +						    match_decoder_by_range);
> +
> +	return cxld_dev ? to_cxl_decoder(cxld_dev) : NULL;
> +}
> +
>  static struct cxl_root_decoder *
>  cxl_find_root_decoder(struct cxl_endpoint_decoder *cxled)
>  {
>  	struct cxl_memdev *cxlmd = cxled_to_memdev(cxled);
>  	struct cxl_port *port = cxled_to_port(cxled);
>  	struct cxl_root *cxl_root __free(put_cxl_root) = find_cxl_root(port);
> -	struct cxl_decoder *cxld = &cxled->cxld;
> +	struct cxl_decoder *root, *cxld = &cxled->cxld;
>  	struct range *hpa = &cxld->hpa_range;
> -	struct device *cxlrd_dev;
>  
> -	cxlrd_dev = device_find_child(&cxl_root->port.dev, hpa,
> -				      match_root_decoder_by_range);
> -	if (!cxlrd_dev) {
> +	root = cxl_port_find_switch_decoder(&cxl_root->port, hpa);
> +	if (!root) {
>  		dev_err(cxlmd->dev.parent,
>  			"%s:%s no CXL window for range %#llx:%#llx\n",
>  			dev_name(&cxlmd->dev), dev_name(&cxld->dev),
> @@ -3239,7 +3245,7 @@ cxl_find_root_decoder(struct cxl_endpoint_decoder *cxled)
>  		return NULL;
>  	}
>  
> -	return to_cxl_root_decoder(cxlrd_dev);
> +	return to_cxl_root_decoder(&root->dev);
>  }
>  
>  static int match_region_by_range(struct device *dev, const void *data)
>