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

Gregory Price
2025-02-20T17:31:11Z

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
>