linux-kernel - Re: [PATCH V4 14/17] cxl/pmem_region: Introduce CONFIG_CXL_PMEM_REGION for core/pmem

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Message-ID: <20251217153847.00001e63@huawei.com>
Date: Wed, 17 Dec 2025 15:38:47 +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 V4 14/17] cxl/pmem_region: Introduce
 CONFIG_CXL_PMEM_REGION for core/pmem_region.c

On Wed, 19 Nov 2025 13:22:52 +0530
Neeraj Kumar <s.neeraj@...sung.com> wrote:

> As pmem region label update/delete has hard dependency on libnvdimm.
> It is therefore put core/pmem_region.c under CONFIG_CXL_PMEM_REGION
> control. It handles the dependency by selecting CONFIG_LIBNVDIMM
> if not enabled.
> 
> Signed-off-by: Neeraj Kumar <s.neeraj@...sung.com>


> diff --git a/drivers/cxl/core/core.h b/drivers/cxl/core/core.h
> index 5ebbc3d3dde5..beeb9b7527b8 100644
> --- a/drivers/cxl/core/core.h
> +++ b/drivers/cxl/core/core.h
> @@ -34,7 +34,6 @@ int cxl_decoder_detach(struct cxl_region *cxlr,
>  #define CXL_REGION_ATTR(x) (&dev_attr_##x.attr)
>  #define CXL_REGION_TYPE(x) (&cxl_region_type)
>  #define SET_CXL_REGION_ATTR(x) (&dev_attr_##x.attr),
> -#define CXL_PMEM_REGION_TYPE(x) (&cxl_pmem_region_type)
>  #define CXL_DAX_REGION_TYPE(x) (&cxl_dax_region_type)
>  int cxl_region_init(void);
>  void cxl_region_exit(void);
> @@ -89,17 +88,23 @@ static inline struct cxl_region *to_cxl_region(struct device *dev)
>  {
>  	return NULL;
>  }
> -static inline int devm_cxl_add_pmem_region(struct cxl_region *cxlr)
> -{
> -	return 0;
> -}
>  #define CXL_REGION_ATTR(x) NULL
>  #define CXL_REGION_TYPE(x) NULL
>  #define SET_CXL_REGION_ATTR(x)
> -#define CXL_PMEM_REGION_TYPE(x) NULL
>  #define CXL_DAX_REGION_TYPE(x) NULL
>  #endif
>  
> +#ifdef CONFIG_CXL_PMEM_REGION
> +#define CXL_PMEM_REGION_TYPE(x) (&cxl_pmem_region_type)
> +int devm_cxl_add_pmem_region(struct cxl_region *cxlr);
> +#else
> +#define CXL_PMEM_REGION_TYPE(x) NULL
> +static inline int devm_cxl_add_pmem_region(struct cxl_region *cxlr)
> +{
> +	return 0;
> +}
> +#endif
> +
>  struct cxl_send_command;
>  struct cxl_mem_query_commands;
>  int cxl_query_cmd(struct cxl_mailbox *cxl_mbox,
> diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
> index 9798120b208e..408e139718f1 100644
> --- a/drivers/cxl/core/region.c
> +++ b/drivers/cxl/core/region.c
> @@ -3918,6 +3918,8 @@ static int cxl_region_probe(struct device *dev)
>  			dev_dbg(&cxlr->dev, "CXL EDAC registration for region_id=%d failed\n",
>  				cxlr->id);
>  
> +		if (!IS_ENABLED(CONFIG_CXL_PMEM_REGION))
> +			return -EINVAL;
>  		return devm_cxl_add_pmem_region(cxlr);

Why not have the stub return -EINVAL if it never makes sense to call without
the CONFIG being enabled?

>  	case CXL_PARTMODE_RAM:
>  		rc = devm_cxl_region_edac_register(cxlr);