linux-kernel - Re: [PATCH v2 04/15] cxl/region: Calculate endpoint's region position during init

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Message-ID: <Z7dm3FeEXVXwJs2O@gourry-fedora-PF4VCD3F>
Date: Thu, 20 Feb 2025 12:31:08 -0500
From: Gregory Price <gourry@...rry.net>
To: Robert Richter <rrichter@....com>
Cc: 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>,
	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,
	"Fabio M. De Francesco" <fabio.m.de.francesco@...ux.intel.com>,
	Terry Bowman <terry.bowman@....com>
Subject: Re: [PATCH v2 04/15] cxl/region: Calculate endpoint's region
 position during init

On Tue, Feb 18, 2025 at 02:23:45PM +0100, Robert Richter wrote:
> diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
> index ad4a6ce37216..6f106bfa115f 100644
> --- a/drivers/cxl/core/region.c
> +++ b/drivers/cxl/core/region.c
> @@ -1903,7 +1903,6 @@ 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);
>  		/*
>  		 * Record that sorting failed, but still continue to calc
>  		 * cxled->pos so that follow-on code paths can reliably
> @@ -3264,10 +3263,22 @@ static int cxl_endpoint_decoder_initialize(struct cxl_endpoint_decoder *cxled)
>  	struct cxl_memdev *cxlmd = cxled_to_memdev(cxled);
>  	struct cxl_port *iter = cxled_to_port(cxled);
>  	struct cxl_decoder *root, *cxld = &cxled->cxld;
> -	struct range *hpa = &cxld->hpa_range;
> +	struct range hpa = cxld->hpa_range;
> +	struct cxl_interleave_context ctx;
> +	int rc;
>  
> -	while (iter && !is_cxl_root(iter))
> -		iter = to_cxl_port(iter->dev.parent);
> +	ctx = (struct cxl_interleave_context) {
> +		.hpa_range = &hpa,
> +	};
> +
> +	while (iter && !is_cxl_root(iter)) {
> +		/* Convert interleave settings to next port upstream. */
> +		rc = cxl_port_calc_interleave(iter, &ctx);

Thinking about it a bit more, you still have cxl_port_calc_interleave
returning the position, but you have the position captured in ctx.

I think you just want to return 0/ERR now since ctx will have the pos.

This makes me think patch 3 and 4 should just be 1 patch.

> +		if (rc < 0)
> +			return rc;
> +
> +		iter = parent_port_of(iter);
> +	}
>  
>  	if (!iter)
>  		return -ENXIO;
> @@ -3281,7 +3292,13 @@ static int cxl_endpoint_decoder_initialize(struct cxl_endpoint_decoder *cxled)
>  		return -ENXIO;
>  	}
>  
> +	dev_dbg(cxld->dev.parent,
> +		"%s:%s: range:%#llx-%#llx pos:%d\n",
> +		dev_name(&cxled->cxld.dev), dev_name(&cxld->dev),
> +		hpa.start, hpa.end, ctx.pos);
> +
>  	cxled->cxlrd = to_cxl_root_decoder(&root->dev);
> +	cxled->pos = ctx.pos;
>  
>  	return 0;
>  }
> -- 
> 2.39.5
>