linux-kernel - Re: [PATCH V5 10/17] cxl/mem: Refactor cxl pmem region auto-assembling

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Message-ID: <20260115180857.00001476@huawei.com>
Date: Thu, 15 Jan 2026 18:08:57 +0000
From: Jonathan Cameron <jonathan.cameron@...wei.com>
To: Neeraj Kumar <s.neeraj@...sung.com>
CC: <linux-cxl@...r.kernel.org>, <nvdimm@...ts.linux.dev>,
	<linux-kernel@...r.kernel.org>, <gost.dev@...sung.com>,
	<a.manzanares@...sung.com>, <vishak.g@...sung.com>, <neeraj.kernel@...il.com>
Subject: Re: [PATCH V5 10/17] cxl/mem: Refactor cxl pmem region
 auto-assembling

On Fri,  9 Jan 2026 18:14:30 +0530
Neeraj Kumar <s.neeraj@...sung.com> wrote:

> In 84ec985944ef3, devm_cxl_add_nvdimm() sequence was changed and called
> before devm_cxl_add_endpoint(). It's because cxl pmem region auto-assembly
> used to get called at last in cxl_endpoint_port_probe(), which requires
> cxl_nvd presence.
> 
> For cxl region persistency, region creation happens during nvdimm_probe
> which need the completion of endpoint probe.
> 
> In order to accommodate both cxl pmem region auto-assembly and cxl region
> persistency, refactored following
> 
> 1. Re-Sequence devm_cxl_add_nvdimm() after devm_cxl_add_endpoint(). This
>    will be called only after successful completion of endpoint probe.
> 
> 2. Create cxl_region_discovery() which performs pmem region
>    auto-assembly and remove cxl pmem region auto-assembly from
>    cxl_endpoint_port_probe()
> 
> 3. Register cxl_region_discovery() with devm_cxl_add_memdev() which gets
>    called during cxl_pci_probe() in context of cxl_mem_probe()
> 
> 4. As cxlmd->ops->probe() calls registered cxl_region_discovery(), so
>    move devm_cxl_add_nvdimm() before cxlmd->ops->probe(). It guarantees
>    both the completion of endpoint probe and cxl_nvd presence before
>    calling cxlmd->ops->probe().
> 
> Reviewed-by: Dave Jiang <dave.jiang@...el.com>
> Signed-off-by: Neeraj Kumar <s.neeraj@...sung.com>

One thing below. With that fixes,
Reviewed-by: Jonathan Cameron <jonathan.cameron@...wei.com>


> diff --git a/drivers/cxl/pci.c b/drivers/cxl/pci.c
> index e21051d79b25..d56fdfe4b43b 100644
> --- a/drivers/cxl/pci.c
> +++ b/drivers/cxl/pci.c
> @@ -907,6 +907,7 @@ static int cxl_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
>  	struct cxl_memdev_state *mds;
>  	struct cxl_dev_state *cxlds;
>  	struct cxl_register_map map;
> +	struct cxl_memdev_ops ops;

Needs init, as there might be other stuff in there.
	struct cxl_memdev_ops ops = {};

>  	struct cxl_memdev *cxlmd;
>  	int rc, pmu_count;
>  	unsigned int i;
> @@ -1006,7 +1007,8 @@ static int cxl_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
>  	if (rc)
>  		dev_dbg(&pdev->dev, "No CXL Features discovered\n");
>  
> -	cxlmd = devm_cxl_add_memdev(&pdev->dev, cxlds, NULL);
> +	ops.probe = cxl_region_discovery;
> +	cxlmd = devm_cxl_add_memdev(&pdev->dev, cxlds, &ops);
>  	if (IS_ERR(cxlmd))
>  		return PTR_ERR(cxlmd);
>