linux-kernel - Re: [PATCH 1/4 v4] cxl/core: Change match_*_by

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Message-ID: <ef74ab77-abf8-4b64-bb3f-9755e9062bee@amd.com>
Date: Fri, 1 Aug 2025 15:04:13 -0500
From: "Cheatham, Benjamin" <benjamin.cheatham@....com>
To: "Fabio M. De Francesco" <fabio.m.de.francesco@...ux.intel.com>
CC: Davidlohr Bueso <dave@...olabs.net>, Jonathan Cameron
	<jonathan.cameron@...wei.com>, Dave Jiang <dave.jiang@...el.com>, "Alison
 Schofield" <alison.schofield@...el.com>, Vishal Verma
	<vishal.l.verma@...el.com>, Ira Weiny <ira.weiny@...el.com>, Dan Williams
	<dan.j.williams@...el.com>, Robert Richter <rrichter@....com>,
	<ming.li@...omail.com>, <linux-kernel@...r.kernel.org>,
	<linux-cxl@...r.kernel.org>
Subject: Re: [PATCH 1/4 v4] cxl/core: Change match_*_by_range() signatures

On 7/24/2025 9:20 AM, Fabio M. De Francesco wrote:
> Replace struct range parameter with struct cxl_endpoint_decoder of
> which range is a member in the match_*_by_range() functions and rename
> them according to their semantics.
> 
> This is in preparation for expanding these helpers to perform arch
> specific Root Decoders and Region matchings with
> cxl_endpoint_decoder(s).
> 
> Cc: Alison Schofield <alison.schofield@...el.com>
> Cc: Dan Williams <dan.j.williams@...el.com>
> Cc: Dave Jiang <dave.jiang@...el.com>
> Cc: Ira Weiny <ira.weiny@...el.com>
> Signed-off-by: Fabio M. De Francesco <fabio.m.de.francesco@...ux.intel.com>
> ---
>  drivers/cxl/core/region.c | 60 +++++++++++++++++++++------------------
>  1 file changed, 33 insertions(+), 27 deletions(-)
> 
> diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
> index 6e5e1460068d..f607e7f97184 100644
> --- a/drivers/cxl/core/region.c
> +++ b/drivers/cxl/core/region.c
> @@ -1759,27 +1759,29 @@ static int cmp_interleave_pos(const void *a, const void *b)
>  	return cxled_a->pos - cxled_b->pos;
>  }
>  
> -static int match_switch_decoder_by_range(struct device *dev,
> -					 const void *data)
> +static int match_switch_and_ep_decoders(struct device *dev, const void *data)
>  {
> +	const struct cxl_endpoint_decoder *cxled = data;
>  	struct cxl_switch_decoder *cxlsd;
> -	const struct range *r1, *r2 = data;
> -
> +	const struct range *r1, *r2;
>  
>  	if (!is_switch_decoder(dev))
>  		return 0;
>  
>  	cxlsd = to_cxl_switch_decoder(dev);
>  	r1 = &cxlsd->cxld.hpa_range;
> +	r2 = &cxled->cxld.hpa_range;
>  
>  	if (is_root_decoder(dev))
>  		return range_contains(r1, r2);
>  	return (r1->start == r2->start && r1->end == r2->end);
>  }
>  
> -static int find_pos_and_ways(struct cxl_port *port, struct range *range,
> -			     int *pos, int *ways)
> +static int find_pos_and_ways(struct cxl_port *port,
> +			     struct cxl_endpoint_decoder *cxled, int *pos,
> +			     int *ways)
>  {
> +	struct range *range = &cxled->cxld.hpa_range;
>  	struct cxl_switch_decoder *cxlsd;
>  	struct cxl_port *parent;
>  	struct device *dev;
> @@ -1789,8 +1791,8 @@ static int find_pos_and_ways(struct cxl_port *port, struct range *range,
>  	if (!parent)
>  		return rc;
>  
> -	dev = device_find_child(&parent->dev, range,
> -				match_switch_decoder_by_range);
> +	dev = device_find_child(&parent->dev, cxled,
> +				match_switch_and_ep_decoders);
>  	if (!dev) {
>  		dev_err(port->uport_dev,
>  			"failed to find decoder mapping %#llx-%#llx\n",
> @@ -1876,7 +1878,7 @@ static int cxl_calc_interleave_pos(struct cxl_endpoint_decoder *cxled)
>  		if (is_cxl_root(iter))
>  			break;
>  
> -		rc = find_pos_and_ways(iter, range, &parent_pos, &parent_ways);
> +		rc = find_pos_and_ways(iter, cxled, &parent_pos, &parent_ways);
>  		if (rc)
>  			return rc;
>  
> @@ -3215,24 +3217,28 @@ static int devm_cxl_add_dax_region(struct cxl_region *cxlr)
>  	return rc;
>  }
>  
> -static int match_decoder_by_range(struct device *dev, const void *data)
> +static int match_root_and_ep_decoders(struct device *dev, const void *data)
>  {
> -	const struct range *r1, *r2 = data;
> -	struct cxl_decoder *cxld;
> +	const struct cxl_endpoint_decoder *cxled = data;
> +	const struct range *r1, *r2;
> +	struct cxl_root_decoder *cxlrd;

Nit: cxlrd should be above the r1, r2 declaration (reverse christmas tree).

>  
> -	if (!is_switch_decoder(dev))
> +	if (!is_root_decoder(dev))
>  		return 0;
>  
> -	cxld = to_cxl_decoder(dev);
> -	r1 = &cxld->hpa_range;
> +	cxlrd = to_cxl_root_decoder(dev);
> +	r1 = &cxlrd->cxlsd.cxld.hpa_range;
> +	r2 = &cxled->cxld.hpa_range;
> +
>  	return range_contains(r1, r2);
>  }

You could reuse the code from match_switch_and_ep_decoders() here by doing:

static int match_root_and_ep_decoders(struct device *dev, const void *data)
{
	if (!is_root_decoder(dev))
		return 0;
	return match_switch_and_ep_decoders(dev, data);
}