linux-kernel - Re: [PATCH v3 05/11] cxl/region: Add @range argument to function cxl_calc_interleave

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Message-ID: <aNMWhG5Ftu8ETYwk@aschofie-mobl2.lan>
Date: Tue, 23 Sep 2025 14:52:04 -0700
From: Alison Schofield <alison.schofield@...el.com>
To: Robert Richter <rrichter@....com>
CC: Vishal Verma <vishal.l.verma@...el.com>, Ira Weiny <ira.weiny@...el.com>,
	Dan Williams <dan.j.williams@...el.com>, Jonathan Cameron
	<Jonathan.Cameron@...wei.com>, Dave Jiang <dave.jiang@...el.com>, "Davidlohr
 Bueso" <dave@...olabs.net>, <linux-cxl@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, Gregory Price <gourry@...rry.net>, "Fabio M.
 De Francesco" <fabio.m.de.francesco@...ux.intel.com>, Terry Bowman
	<terry.bowman@....com>, Joshua Hahn <joshua.hahnjy@...il.com>
Subject: Re: [PATCH v3 05/11] cxl/region: Add @range argument to function
 cxl_calc_interleave_pos()

On Fri, Sep 12, 2025 at 04:45:07PM +0200, Robert Richter wrote:
> cxl_calc_interleave_pos() uses the endpoint decoder's HPA range to
> determine its interleaving position. This requires the endpoint
> decoders to be an SPA, which is not the case for systems that need
> address translation.
> 
> Add a separate @range argument to function cxl_calc_interleave_pos()
> to specify the address range. Now it is possible to pass the SPA
> translated address range of an endpoint decoder to function
> cxl_calc_interleave_pos().
> 
> Patch is a prerequisite to implement address translation.
> 
> Signed-off-by: Robert Richter <rrichter@....com>
> ---
>  drivers/cxl/core/region.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
> index 8ccc171ac724..106692f1e310 100644
> --- a/drivers/cxl/core/region.c
> +++ b/drivers/cxl/core/region.c
> @@ -1844,11 +1844,11 @@ static int find_pos_and_ways(struct cxl_port *port, struct range *range,
>   * Return: position >= 0 on success
>   *	   -ENXIO on failure
>   */
> -static int cxl_calc_interleave_pos(struct cxl_endpoint_decoder *cxled)
> +static int cxl_calc_interleave_pos(struct cxl_endpoint_decoder *cxled,
> +				   struct range *range)
>  {
>  	struct cxl_port *iter, *port = cxled_to_port(cxled);
>  	struct cxl_memdev *cxlmd = cxled_to_memdev(cxled);
> -	struct range *range = &cxled->cxld.hpa_range;
>  	int parent_ways = 0, parent_pos = 0, pos = 0;
>  	int rc;

Will this work? Change the assignment rather than adding a parameter:

-       struct range *range = &cxled->cxld.hpa_range;
+       struct range *range = &cxled->cxld.region->hpa_range;



>  
> @@ -1909,7 +1909,7 @@ static int cxl_region_sort_targets(struct cxl_region *cxlr)
>  	for (i = 0; i < p->nr_targets; i++) {
>  		struct cxl_endpoint_decoder *cxled = p->targets[i];
>  
> -		cxled->pos = cxl_calc_interleave_pos(cxled);
> +		cxled->pos = cxl_calc_interleave_pos(cxled, &cxlr->hpa_range);
>  		/*
>  		 * Record that sorting failed, but still continue to calc
>  		 * cxled->pos so that follow-on code paths can reliably
> @@ -2093,7 +2093,7 @@ static int cxl_region_attach(struct cxl_region *cxlr,
>  		struct cxl_endpoint_decoder *cxled = p->targets[i];
>  		int test_pos;
>  
> -		test_pos = cxl_calc_interleave_pos(cxled);
> +		test_pos = cxl_calc_interleave_pos(cxled, &cxlr->hpa_range);
>  		dev_dbg(&cxled->cxld.dev,
>  			"Test cxl_calc_interleave_pos(): %s test_pos:%d cxled->pos:%d\n",
>  			(test_pos == cxled->pos) ? "success" : "fail",
> -- 
> 2.39.5
>